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Chemoprotective effects of curcumin in esophageal epithelial cells exposed to bile acids


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To investigate the ability of curcumin to counteract the impact of bile acids on gene expression of esophageal epithelial cells. An esophageal epithelial cell line (HET-1A) was treated with curcumin in the presence of deoxycholic acid. Cell proliferation and viability assays were used to establish an appropriate dose range for curcumin. The combined and individual effects of curcumin and bile acid on cyclooxygenase-2 (COX-2) and superoxide dismutase (SOD-1 and SOD-2) gene expression were also assessed. Curcumin in a dose range of 10-100 micromol/L displayed minimal inhibition of HET-1A cell viability. Deoxycholic acid at a concentration of 200 micromol/L caused a 2.4-fold increase in COX-2 gene expression compared to vehicle control. The increased expression of COX-2 induced by deoxycholic acid was partially reversed by the addition of curcumin, and curcumin reduced COX-2 expression 3.3- to 1.3-fold. HET-1A cells exposed to bile acid yielded reduced expression of SOD-1 and SOD-2 genes with the exception that high dose deoxycholic acid at 200 mumol/L led to a 3-fold increase in SOD-2 expression. The addition of curcumin treatment partially reversed the bile acid-induced reduction in SOD-1 expression at all concentrations of curcumin tested. Curcumin reverses bile acid suppression of gene expression of SOD-1. Curcumin is also able to inhibit bile acid induction of COX-2 gene expression.
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Chemoprotective effects of curcumin in esophageal
epithelial cells exposed to bile acids
Matthew R Bower, Harini S Aiyer, Yan Li, Robert CG Martin
Matthew R Bower, Harini S Aiyer, Yan Li, Robert CG Mar-
tin, Division of Surgical Oncology, Department of Surgery and
James Graham Brown Cancer Center, University of Louisville
School of Medicine, Louisville, KY 40202, United States
Author contributions: Bower MR and Aiyer HS designed and
performed the research, prepared the manuscript; Martin RCG
supervised the research design and manuscript preparation; Li Y
supervised the design and performance of the research.
Supported by National Institutes of Health Grant, No. 1R03-
Correspondence to: Robert CG Martin, MD, PhD, Division
of Surgical Oncology, Department of Surgery and James Gra-
ham Brown Cancer Center, University of Louisville School of
Medicine, 315 East Broadway - Rm 313, Louisville, KY 40202,
United States.
Telephone: +1-502-6293355 Fax: +1-502-6293030
Received: February 9, 2010 Revised: March 28, 2010
Accepted: April 4, 2010
Published online: September 7, 2010
AIM: To investigate the ability of curcumin to coun-
teract the impact of bile acids on gene expression of
esophageal epithelial cells.
METHODS: An esophageal epithelial cell line (HET-
1A) was treated with curcumin in the presence of
deoxycholic acid. Cell proliferation and viability assays
were used to establish an appropriate dose range for
curcumin. The combined and individual effects of cur-
cumin and bile acid on cyclooxygenase-2 (
) and
superoxide dismutase (
) gene ex-
pression were also assessed.
RESULTS: Curcumin in a dose range of 10-100 μmol/L
displayed minimal inhibition of HET-1A cell viability. De-
oxycholic acid at a concentration of 200 μmol/L caused
a 2.4-fold increase in
gene expression compared
to vehicle control. The increased expression of
induced by deoxycholic acid was partially reversed by
the addition of curcumin, and curcumin reduced
expression 3.3- to 1.3-fold. HET-1A cells exposed to bile
acid yielded reduced expression of
genes with the exception that high dose deoxycholic
acid at 200 μmol/L led to a 3-fold increase in
expression. The addition of curcumin treatment partially
reversed the bile acid-induced reduction in
pression at all concentrations of curcumin tested.
CONCLUSION: Curcumin reverses bile acid suppres-
sion of gene expression of
. Curcumin is also
able to inhibit bile acid induction of
gene ex-
© 2010 Baishideng. All rights reserved.
Key words: Esophageal cancer; Curcumin; Cyclooxy-
genase-2; Superoxide dismutase; Chemoprevention
Peer reviewers: Paul M Schneider, MD, Professor, Department
of Surgery, University Hospital Zurich, Raemistrasse 100, Zur-
ich, 8091, Switzerland; Tomohiko Shimatani, Assistant Professor,
Department of General Medicine, Hiroshima University Hospital,
1-2-3 Kasumi, Minami-ku, Hiroshima 7348551, Japan; Robert J
Korst, MD, Department of Cardiothoracic Surgery, Weill Medical
College of Cornell University, Room M404, 525 East 68th Street,
New York, NY 10032, United States
Bower MR, Aiyer HS, Li Y, Martin RCG. Chemoprotective ef-
fects of curcumin in esophageal epithelial cells exposed to bile
acids. World J Gastroenterol 2010; 16(33): 4152-4158 Available
from: URL:
4152.htm DOI:
Over the past three decades the incidence of esophageal
adenocarcinoma has increased over four-fold, and the cur-
rent ve year survival remains only 10%-20%[1]. Esopha-
geal adenocarcinoma is known to develop in the distal
esophagus in the setting of exposure to both bile acids and
low pH[2-4]. The exact cellular mechanisms underlying this
World J Gastroenterol 2010 September 7; 16(33): 4152-4158
ISSN 1007-9327 (print)
© 2010 Baishideng. All rights reserved.
Online Submissions:ce
September 7, 2010
Volume 16
Issue 33
Bower MR
et al
. Curcumin and bile acid exposure in esophageal cells
process are largely unknown. Oxidative stress has been
theorized to play a signicant role in the staged progres-
sion from reflux esophagitis to Barrett’s esophagus and
eventually to esophageal adenocarcinoma. Increased levels
of reactive oxygen species (ROS) and oxidative injury have
been detected in esophageal cells exposed to low pH and
bile acids[5-7], and the level of free radicals in esophageal
tissue has also been associated with the degree of esopha-
gitis[8]. In addition, we have previously shown an associa-
tion between the development of esophageal adenocarci-
noma and increased levels of 8-hydroxy-deoxyguanosine,
an indicator of oxidative damage, using an esophageal
duodenal anastomosis rat model of reux esophagitis[9].
Based on these findings, compounds with antioxi-
dant properties may hold promise as chemopreventative
agents in the Barrett’s metaplasia-dyplasia-adenocarcino-
ma sequence. Curcumin is a phenolic compound derived
from the plant Curcuma longa. Curcumin is known to
have both anti-inammatory and antioxidant properties.
A number of animal and in vitro models have also shown
curcumin to be a potent chemopreventative agent[10,11].
Previous work by Li et al[12] demonstrated in a rat model
of esophageal reflux that intraperitoneal injections of
curcuma aromatic oil, a volatile oil extract of Curcuma
aromatica, helped prevent the development of esophageal
adenocarcinoma. However, the molecular mechanisms
by which curcumin may inhibit the development of
esophageal adenocarcinoma have not been fully dened.
In the current study, HET-1A cells were used as an
in vitro model to study the potential impact of curcumin
on the initial changes induced by bile acids in the esopha-
gus. HET-1A cells are a well characterized, non-cancerous,
SV-40 T-antigen immortalized human esophageal epithe-
lial cell line[13]. HET-1A cells have been shown to produce
ROS after brief exposures to low pH and to bile acids[6,14].
HET-1A cells develop gene expression changes consistent
with the development of Barrett’s esophagus upon ex-
posure to deoxycholic acid[15], and carcinogens have been
found to induce tumorigenic characteristics within these
cells[16,17]. Furthermore, previous work by Raee et al[18] has
shown that curcumin has an anti-inammatory effect on
HET-1A cells by inhibition of acidic pH-induced secre-
tion of cytokines interleukin (IL)-8 and IL-9.
We tested the hypothesis that curcumin prevents
the bile acid-mediated impairment of HET-1A cellular
mechanisms for managing oxidative stress. Specifically,
we investigated the impact of bile acid and curcumin on
expression of the human gene forms of superoxide dis-
mutase (SOD-1 and SOD-2). The ideal curcumin dose in
combination with bile acid in vitro was determined through
cell proliferation and viability testing. Curcumin- and bile
acid-induced alterations of cyclooxygenase-2 (COX-2)
gene expression were also studied as an additional mecha-
nism of esophageal adenocarcinoma prevention. The aim
of this study was to determine whether curcumin has ef-
fects on esophageal cell gene expression consistent with a
chemopreventative in the setting of bile acid exposure.
Curcumin was obtained from LKT Laboratories, Inc. (St.
Paul, MN). 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-
2H-tetrazolium (MTT) and cDNA Trizol reagent were
obtained from Sigma Chemical Co. (St. Louis, MO).
5-bromo-2’-deoxyuridine (BrdU) ELISA assay kits were
purchased from Roche Applied Science (Indianapolis,
IN). All other chemicals were purchased from Sigma
Chemical Co. (St. Louis, MO) unless otherwise stated.
Cell culture
HET-1A cells, a SV-40 immortalized human esophageal
epithelial cell line, were acquired from the American Type
Culture Collection and grown in bronchial epithelial
growth media (BEGM) and recommended supplements
(BEGM Bullet Kit) obtained from Lonza Bio Science
(Walkersville, MD). The growth media was also supple-
mented with 10% fetal bovine serum. Cells were grown in
a monolayer and incubated at 37 in 5% CO2 and 90%
relative humidity.
For cellular proliferation and viability studies, HET-1A
cells were plated in 96-well microtiter plates at a density
of 1 × 104 cells per well and allowed to attach and grow
for 48 h prior to treatment. The cells were treated with
varying doses (100 nmol/L-1 mmol/L) of curcumin dis-
solved in ethanol and added to fresh media for a total eth-
anol concentration that did not exceed 2.5%. Treatment
with deoxycholic acid (in ethanol) at a concentration of
100 μmol/L combined with curcumin was also per-
formed. A vehicle control of media and 2.5% ethanol was
used to study the effect of ethanol, and all treated groups
were compared to this control. Treatments were conduct-
ed for 24 h.
For mRNA expression studies, HET-1A cells were
plated in 6-well plates at a density of 1.5 × 105 cells per
well and grown for 48 h. Curcumin and deoxycholic
acid dissolved in ethanol were added with fresh media at
varying concentrations. The nal ethanol concentration
was maintained at 0.2%, and 0.2% ethanol solution was
used as a vehicle control. All studies were performed in
triplicate to conrm reproducibility.
Cell viability and cell proliferation assays
MTT assays were conducted as described previously
Briey, treated media was aspirated without disrupting the
cells at the bottom of the plate. MTT at a concentration
of 5 mg/mL was dissolved in phosphate buffered saline
(PBS) and added to each well. After incubation at 37
for 2 h, the MTT solution was aspirated and the wells
were air-dried. DMSO was added to the wells and the ab-
sorbance was read at 570 nm in a spectrophotometer.
Cell proliferation assay based on incorporation of
BrdU was used to investigate the effect of the various
treatments. After the 24 h treatments, the BrdU ELISA
was performed according to the manufacturer’s directions.
4153 September 7, 2010
Volume 16
Issue 33
RNA extraction and real-time polymerase chain reaction
RNA was isolated using the Trizol® method (Invitrogen,
Carlsbad, CA). All procedures were carried out in an
RNase free environment. The quality of the RNA was
ascertained by gel electrophoresis and quantitated using
NanoDrop® (NanoDrop Technologies, Wilmington, DE).
The RNA was then diluted to 5 ng/μL concentration and
stored at -80 until use. Equal amounts of RNA (0.1 μg)
were reverse transcribed using a high-capacity cDNA ar-
chive kit (Applied Biosystems, Forster City, CA) according
to the manufacturer’s instructions.
Primers for quantitative real-time polymerase chain
reaction (RT-PCR) were designed across exon boundaries
to avoid amplication of genomic DNA, using Primer ex-
press® 3.0 software (Applied Biosystems, Foster City, CA)
and synthesized by Integrated DNA Technologies, Inc.,
(Coralville, IA). The sequences of the forward and reverse
primers for each gene tested are listed in Table 1.
The PCR amplication was carried out in a nal reac-
tion volume of 20 μL containing 1 × Power SYBR® Green
PCR master mix (Applied Biosystems, CA); 10 nmol/L
each of forward and reverse primers specic for each gene
and 40 ng of cDNA. Quantitative PCR was performed us-
ing a 7300 Prizm (Applied Biosystems, Foster City, CA) us-
ing the relative quantication protocol. The PCR conditions
were: 50 for 2 min; DNA polymerase activation at 95
for 10 min; followed by 40 cycles at 95 for 15 s and 60
for 1 min. The 2-ΔΔCt method was used to determine gene
quantication with human β-actin used as an endogenous
reference gene. Results were expressed as fold change in
gene expression compared to the vehicle control.
Statistical analysis
Relative fold changes in each group were compared us-
ing one-way analysis of variance (ANOVA), followed by
a Tukey’s multiple comparison post test. A P-value < 0.05
was considered signicant. All statistical analyses were per-
formed using SPSS Version 17 (SPSS Inc., Chicago, IL).
Dose response effects of curcumin on cell viability and
In order to establish a sub-toxic dose of curcumin, the
inuence of curcumin on HET-1A cell viability and pro-
liferation was assessed using both MTT and BrdU assays,
respectively. Similar trends were seen for both BrdU and
MTT assays (Figure 1A and B). Compared to the vehicle
control, all concentrations of curcumin tested showed sig-
nicant reduction in cell viability as demonstrated by the
MTT assay (33% to 58% reduction, P < 0.01). The cyto-
toxicity and reduction in proliferation were higher at con-
centrations greater than 100 μmol/L when compared to
the vehicle control (MTT: 1 mmol/L - 48%, 100 μmol/L
- 58%, P < 0.001; BrdU: 1 mmol/L - 80%, 100 μmol/L
- 73%, P 0.01) (Figure 1A). However, less cytotoxicity
was seen at curcumin concentrations less than 10 μmol/L
(MTT: 30%-40%, P < 0.01), and curcumin did not ad-
4154 September 7, 2010
Volume 16
Issue 33
Table 1 Primer sequences for quantitative real-time polymerase chain reaction
Gene Forward Reverse
COX: Cyclooxygenase; SOD: Superoxide dismutase.
Percent cell viability or proliferation
DCA - - + - +
(100 μmol/L)
Curcumin - 1 mmol/L 1 mmol/L 100 μmol/L 100 μmol/L
Percent cell viability or proliferation
DCA - - + - + - +
(100 μmol/L)
Curcumin - 10 μmol/L 10 μmol/L 1 μmol/L 1 μmol/L 100 nmol/L 100 nmol/L
Figure 1 Effect of curcumin concentration on cell viability and proliferation
at concentration 100 μmol/L (A) and 10 μmol/L (B). HET-1A cells
incubated in 96-well plates at a density of 10 000 cells/well for 24 h demonstrated
decreased cell viability and proliferation in the presence of curcumin at a
concentration 100 μmol/L or 10 μmol/L. The viability and proliferation were
also reduced in the presence of curcumin combined with deoxycholic acid (DCA)
when compared to vehicle control (2.5% ethanol). aP < 0.05 vs vehicle control.
MTT: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium; BrdU: 5-bromo-2’-
deoxyuridine; DCA: Deoxycholic acid.
Bower MR
et al
. Curcumin and bile acid exposure in esophageal cells
versely effect cell proliferation at these concentrations, as
demonstrated by the BrdU assay (10%-14% reduction,
P > 0.05) (Figure 1B). When cells were treated with de-
oxycholic acid (100 μmol/L) combined with varying cur-
cumin concentrations, increased cytotoxicity was seen at
each concentration of curcumin tested (Figure 1A and B).
Again, the greatest cytotoxicity was demonstrated at doses
of curcumin greater than 100 μmol/L (P < 0.001). All
doses of curcumin tested caused synergistic cytotoxicity in
the presence of deoxycholic acid (100 μmol/L).
Combined effects of deoxycholic acid and curcumin on
COX-2 gene expression
We investigated the effects of curcumin on COX-2 gene
expression in HET-1A cells (Figure 2A and B). It was ob-
served that 24 h curcumin treatment alone had minimal
impact on COX-2 mRNA production. The degree of
COX-2 mRNA production was unaltered even at doses
of 100 μmol/L. Increased levels of COX-2 mRNA were
observed in HET-1A cells treated with bile acid alone. De-
oxycholic acid at 200 μmol/L caused a 2.4-fold increase
in COX-2 mRNA levels compared to vehicle control.
The increased expression of COX-2 genes induced by
deoxycholic acid was partially reversed by the addition of
curcumin. It was observed that treatment of HET-1A
cells with deoxycholic acid and curcumin reduced COX-2
mRNA levels 3.3- to 1.3-fold. Curcumin inhibition of bile
acid-induced COX-2 expression was observed at doses
as low as 1 μmol/L curcumin. This effect was not dose-
dependent, with 50 μmol/L curcumin showing the great-
est effect.
Combined effects of deoxycholic acid and curcumin on
SOD-1 and SOD-2 gene expression
Measurements were also made of SOD gene expres-
sion following curcumin treatment of HET-1A cells for
24 h. Two human gene forms of superoxide dismutase
were tested: Cu/ZnSOD (SOD-1) and MnSOD (SOD-2).
Results revealed that curcumin treatment led to a non-
significant 36% to 52% reduction in SOD-1 expression
at all concentrations of curcumin tested. Curcumin alone
also had a non-significant impact on SOD-2 expression
(Figure 3A). Compared to controls, bile acid treatment
of HET-1A cells yielded consistent reduction of SOD-1
and SOD-2 mRNA production, with the exception that
high dose deoxycholic acid at 200 μmol/L led to a 3-fold
increase in SOD-2 expression. Deoxycholic acid inhibited
the expression of SOD-1 (2.8- to 4.0-fold) at concentra-
tions 50 μmol/L (Figure 3B). The addition of curcum-
in treatment reversed this reduction in SOD-1 expression
induced by bile acid at all concentrations of curcumin
tested (Figure 3B). The combined treatment of deoxycho-
lic acid and curcumin resulted in reduced expression of
SOD-2 at concentrations 50 μmol/L (Figure 3C).
The purpose of this study was to investigate the poten-
tial of curcumin as a chemopreventative in the develop-
ment of reflux-induced esophageal adenocarcinoma
using an in vitro model of HET-1A human esophageal
epithelial cells. This study demonstrates that curcumin
can attenuate certain effects of bile acid on HET-1A cell
gene expression. Specifically, this analysis reveals that
curcumin is able to partially reverse bile acid suppres-
sion of gene expression of the free radical scavenger
superoxide dismutase in the form of SOD-1; however,
the impact toward SOD-2 was variable. In addition, cur-
cumin was noted to inhibit bile acid induction of COX-2
gene expression in esophageal epithelial cells.
Several factors were taken into consideration to es-
tablish the in vitro model. Of the potentially available bile
acids, the cells were exposed to deoxycholic acid because
it has been commonly detected in aspirates of patients
with Barrett’s esophagus[20], and deoxycholic acid has
been shown to induce DNA damage in esophageal cells
through oxidative injury[21]. Also important to the model
was establishing an in vitro therapeutic dosage range for
curcumin, as curcumin is known to induce apoptosis in
4155 September 7, 2010
Volume 16
Issue 33
Fold change
Curcumin - 1 μmol/L 50 μmol/L 100 μmol/L
Figure 2 Effect of curcumin and deoxycholic acid on cyclooxygenase-2
gene expression. A: Effect of curcumin on cyclooxygenase-2 (COX-2) gene
expression. HET-1A cells in 6-well plates at a density of 1.5 × 105 cells per well
incubated with curcumin for 24 h showed unaltered gene expression of COX-2
when compared to vehicle control (0.2% ethanol). Error bars: mean ± SD (n =
4); B: Effect of both deoxycholic acid and curcumin on COX-2 gene expression.
HET-1A cells in 6-well plates at a density of 1.5 × 105 cells per well incubated
with deoxycholic acid (DCA) for 24 h showed increased gene expression of
COX-2 with increasing doses of DCA when compared to vehicle control (0.2%
ethanol). The addition of curcumin diminished the increase in gene expression.
Error bars: mean ± SD (n = 4).
Fold change
DCA (μmol/L) - 50 100 200 100 100 100
Curcumin - - - - 1 50 100
Bower MR
et al
. Curcumin and bile acid exposure in esophageal cells
both malignant and non-malignant cell types. Curcumin
concentrations less than 10 μmol/L had the least impact
on esophageal cell viability and proliferation in the pres-
ence of bile acid, and concentrations in the range of
50 μmol/L had the most dramatic impact on esophageal
cell gene expression. This dosage range was valid because
only curcumin concentrations greater than 100 μmol/L
showed signicant toxicity. The greatest toxicity was seen
in curcumin doses higher than 100 μmol/L in combina-
tion with bile acid, which led to a 2- to 5-fold decrease in
the proliferation and viability of HET 1-A cells.
The results revealed that curcumin did not inhibit the
baseline expression of COX-2 genes by HET-1A cells,
but curcumin did show suppression of bile acid-induced
expression of COX-2 genes. Curcumin has been previ-
ously noted to inhibit both the activity and expression of
COX-2 in colon cancer cells[22,23], and it has been shown
that curcumin inhibits bile acid-induced COX-2 expres-
sion and activity in esophageal adenocarcinoma and
squamous cell carcinoma cell lines[24]. Animal models have
shown that COX-2 inhibition can potentially prevent the
development of esophageal adenocarcinoma and Barrett’s
esophagus[25,26]. Epidemiologic studies have also suggested
that the use of COX-2 inhibitors leads to lower rates
of esophageal adenocarcinoma[27]. The use of selective
COX-2 inhibitors has recently fallen out of favor due to
their cardiotoxic side effects[28], and non-selective cyclo-
oxygenase inhibitors such as aspirin have potential gastro-
intestinal effects that make them unappealing therapeutic
agents in patients already suffering from reflux. There-
fore, curcumin may represent a safe alternative means of
COX-2 inhibition in patients with GERD.
Curcumin and bile acid treatments of HET-1A cells
revealed variable alterations of SOD gene expression.
Superoxide dismutase is the primary scavenger of super-
oxide anion which has been implicated as the primary re-
active oxygen species involved in reux-induced oxidative
damage[29-32]. Impairment of cellular antioxidant mecha-
nisms that manage superoxide anions may contribute to
the processes underlying esophageal mucosal injury by
bile acids. Supplementation with SOD has been found
to be protective against reflux-induced damage of the
esophagus in rats[33]. Also, decreased activity of MnSOD
has been measured in esophageal tissue of patients with
esophagitis and Barrett’s esophagus[29,34]. Using the esoph-
ageal duodenal anastomosis-based rat model, we have
previously demonstrated a decreased incidence of Bar-
rett’s esophagus and esophageal adenocarcinoma accom-
panied by decreased oxidative injury in rats treated with
Mn(III)tetrakis(4-benzoic acid) porphyrin (MnTBAP), an
SOD mimetic[34].
Curcumin alone had minimal impact on either SOD-1
or SOD-2 expression. Bile acid induced SOD-2 gene ex-
pression, but inhibited SOD-1 gene expression. Curcumin
ameliorated the effect of bile acid on SOD-1, causing a
decrease in the degree of suppression. These findings
are in contrast to previous work using a rat model of bile
reux demonstrating that esophagitis was associated with
decreased SOD-2 enzyme production and activity and
had no association with the activity and expression of
SOD-1[35]. Other work by Jiménez et al[29] found increased
4156 September 7, 2010
Volume 16
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Fold change
Curcumin - 1 μmol/L 50 μmol/L 100 μmol/L
Fold change
DCA (μmol/L) - 50 100 200 100 100 100
Curcumin - - - - 1 50 100
Figure 3 Effect of curcumin and bile acid on superoxide dismutase gene
expression. A: Effect of curcumin on superoxide dismutase (SOD)-1 and SOD-2
gene expression. HET-1A cells in 6-well plates at a density of 1.5 × 105 cells per
well incubated with curcumin for 24 h did not show a signicant impact on SOD-1
or SOD-2 gene expression. Error bars: mean ± SD (n = 4); B: Effect of curcumin
and bile acid on SOD-1 gene expression. HET-1A cells in 6-well plates at a density
of 1.5 × 105 cells per well incubated with deoxycholic acid (DCA) for 24 h showed
a signicant decrease in SOD-1 expression. When DCA treatment at 100 μmol/L
was combined with curcumin the suppression in SOD-1 expression was alleviated.
Error bars: mean ± SD (n = 4). aP < 0.05 vs vehicle control; C: Effect of curcumin
and bile acid on SOD-2 gene expression. HET-1A cells in 6-well plates at a density
of 1.5 × 105 cells per well incubated with deoxycholic acid (DCA) for 24 h showed
a signicant increase in SOD-2 expression at a DCA concentration of 200 μmol/L.
The combined treatment of DCA and curcumin showed reduced expression of
SOD-2 at concentrations 50 μmol/L. Error bars: mean ± SD (n = 4).
Fold change
DCA (μmol/L) - 50 100 200 100 100 100
Curcumin - - - - 1 50 100
Bower MR
et al
. Curcumin and bile acid exposure in esophageal cells
SOD-1 and SOD-2 expression in esophageal biopsies of
patients with Barrett’s and reux esophagitis as compared
to normal controls. However, the overall SOD activity
was decreased in patients with esophagitis and Barrett’s
esophagus compared to normal epithelium. In another
investigation using human esophageal biopsy specimens,
Sihvo et al[36] found that only specimens of Barrett’s as-
sociated with dysplasia showed increased SOD activity.
These conicting data illustrate that complex mechanisms
related to both the timing and extent of bile acid exposure
likely play a role in altering SOD expression and its impact
on the development of esophageal adenocarcinoma. Cur-
cumin as a preservative of SOD-1 expression in the early
phase of bile acid exposure may provide a mechanism for
the chemoprevention of esophageal adenocarcinoma.
A major difculty of in vitro studies of reux and Bar-
rett’s esophagus is the inability to replicate the timing and
nature of acid exposure in the distal esophagus. We were
limited as to the concentration of bile acid that could be
used due to the degree of cellular toxicity in the pres-
ence of curcumin. As a result, the concentrations of bile
acid tested were lower than those that can occur in the
distal esophagus of patients with gastroesophageal reux,
which have been measured as high as 1 to 2 mmol/L[3].
Therefore, the bile acid levels tested may have been too
low to induce the degree of gene expression changes that
are experienced in vivo. Adjustments were also not made
for varying pH levels of the experiments, and our study
looked at 24 h exposure times to bile acids and curcumin.
Longer exposure times and different pH levels may yield
different results with respect to gene expression.
Curcumin has previously been investigated as a che-
mopreventive agent in a small number of phase
phase trials and found to be safe and well tolerated[37-39].
However, a primary impediment to the use of curcumin
has been its poor bioavailability as a result of extensive
metabolization in the human gut[40]. This may be less of
a drawback for curcumin use in the esophagus, as initial
exposure to curcumin would occur prior to intestinal me-
tabolism. Also, current work on developing lipolized or
heat-solubilized forms of curcumin may help overcome
this issue[38,41]. The current study provides a basis for pos-
sible use of curcumin for chemoprevention of esophageal
adenocarcinoma through its effects on bile acid-induced
alterations of COX-2 and SOD gene expression. Curcumin
should be further investigated as a chemopreventative agent
in the setting of reux esophagitis and Barrett’s esophagus.
The incidence of esophageal adenocarcinoma has increased dramatically over
the past few decades. Oxidative injury resulting from the reux of bile acids is
thought to play a role in the development of esophageal adenocarcinoma. Cur-
cumin is a naturally occurring antioxidant derived from the herb turmeric, that
might potentially counteract the effects of bile acids on esophageal cells.
Research frontiers
Curcumin has demonstrated anticancer properties in a variety of tumor types.
Curcumin is also known to impact the gene expression of a variety of enzymes.
This study analyzes the possible effects of curcumin on bile acid-induced al-
terations of gene expression by esophageal cells.
Innovations and breakthroughs
This study is one of the rst to report that curcumin may have chemopreventa-
tive effects on esophageal cells in the presence of bile acids. The results of this
research also suggest a dosage range of curcumin that is effective in altering
esophageal cell gene expression. Understanding this therapeutic dosage range
has important implications for future in vivo studies of curcumin, as it is known
to have limited bioavailability.
By demonstrating that curcumin effects the production of cyclooxygenase-2
(COX-2) and antioxidant enzymes, this study suggests a possible use for cur-
cumin as a chemopreventative against esophageal adenocarcinoma.
HET-1A cells are an epithelial cell line derived from human esophagus. Su-
peroxide dismutase (SOD) is an important enzyme responsible for managing
the reactive oxygen species, superoxide. COX-2 is an enzyme involved in the
formation of certain inammatory mediators.
Peer review
In this manuscript, the authors determined a basis for possible use of curcumin
for chemoprevention of esophageal adenocarcinoma through its effects on bile
acid-induced alterations of COX-2 and SO D gene expression. This is a very
interesting paper for the scientic community involved in Barrett’s esophagus
and Barrett’s cancer research. Good design, good technical performance and
critical discussion.
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S- Editor Wang JL L- Editor Logan S E- Editor Ma WH
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... Additionally, it can modulate enzymes in the neutralization of free radicals such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase by blocking the PI3K/Akt/NF-κB signaling pathway (Hewlings & Kalman, 2017;Li et al., 2018;Lin et al., 2007). Also, SOD gene expression was found to be suppressed by bile acid, which was reversed by curcumin treatment (Bower et al., 2010). ...
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Curcumin, as the main natural compound in the turmeric plant (Curcuma longa), is a yellowish polyphenol that has been used traditionally in Asian countries as a medicinal herb for various types of disease and pathological conditions caused by inflammation and oxidative stress. In the present review, we conducted a comprehensive literature search for evidence that shows the effect of curcumin on factors influencing exercise performance, including muscle damage, muscle soreness, inflammation, and oxidative stress. During exercise, reactive oxygen species and inflammation are increased. Thus, if there is no balance between endogenous and exogenous antioxidants and increases in oxidative stress and inflammation, which is important for maintaining redox homeostasis in skeletal muscle, it can lead to muscle soreness and muscle damage and ultimately result in reduced exercise performance. Due to the anti‐oxidant and anti‐inflammatory properties of curcumin, it can increase exercise performance and decrease exercise‐induced muscle soreness and muscle damage. It appears that curcumin supplementation can have positive effects on exercise performance and recovery, muscle damage and pain, inflammation, and oxidative stress. However, there is still a need to precisely evaluate factors to more accurately assess/quantify the beneficial therapeutic effects of curcumin with regard to enhancing exercise performance and recovery. Curcumin, by functioning as an antioxidant, may reduce oxidative stress to cells, and especially mitochondria, in the long‐term, as well as positively impact exercise endurance, strength, and recovery to improve overall health.
... Indeed, comparably to the antiinflammatory effects, the antineoplastic effects would occur through the modulation of critical intracellular signaling pathways such as the NF-κB pathway. 85 The potential chemopreventive effects of curcumin have been observed in several preclinical models [86][87][88] and a few human studies. [89][90][91] In addition to reducing the inflammatory cancer microenvironment, these effects might be due to the promotion of apoptosis, inhibition of survival signals, and scavenging of reactive oxidative species. ...
... Curcumin as a phytochemical, has been widely explored for its therapeutic potential through in vitro and in vivo investigations. It has been shown to possess biological activity against a large spectrum of physiological conditions, which include antioxidant [17][18][19][20] , chemo-protective [21][22][23] , antidiabetic [24][25][26] and anti-proliferative activity against cancer cells [27][28][29][30][31] . ...
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Curcumin, a polyphenol, has a wide range of biological properties such as anticancer, antibacterial, antitubercular, cardioprotective and neuroprotective. Moreover, the anti-proliferative activities of Curcumin have been widely studied against several types of cancers due to its ability to target multiple pathways in cancer. Although Curcumin exhibited potent anticancer activity, its clinical use is limited due to its poor water solubility and faster metabolism. Hence, there is an immense interest among researchers to develop potent, water-soluble, and metabolically stable Curcumin analogs for cancer treatment. While drug resistance remains a major problem in cancer therapy that renders current chemotherapy ineffective, curcumin has shown promise to overcome the resistance and re-sensitize cancer to chemotherapeutic drugs in many studies. In the present review, we are summarizing the role of curcumin in controlling the proliferation of drug-resistant cancers and development of curcumin-based therapeutic applications from cell culture studies up to clinical trials.
... The primary active ingredient of turmeric is in a group of three curcuminoid. Curcumin (Difeurloylmethane), the yellow pigment of turmeric considered as anti-oxidant, anti-microbial, anti-fungal, antiviral and anti-inflammatory, anti-carcinogenic agent (Bower et al., 2010). Recent studies, and extensive review literature has also proved curcumin role in enhancement of wound healing (Singh et al., 2010), reducing blood cholesterol (Xiao et al., 2008). ...
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Acrylamide is a chemical compound which is formed in starchy foods such as crisps, chips, bread and crisp breads when cooked at high temperatures. It was first discovered by Scientists in Sweden in 2002. The main purpose of this investigation was to study the effect of some phytochemicals and their rich sources such as curcumin and turmeric or gallic acid and green tea on the reduction of acrylamide formation during frying process of potato chips by using some technological treatments for oil .The biological effects of these phytochemicals on the reduction of harmful effect of acrylamide on lipid profile were also investigated. The results showed that treatment with curcumin (0.1 and 0.3%) and turmeric at different concentrations (0.5 and 1%) had reduced the formation of acrylamide in potato chips. The rate of reduction increased with prolonged frying time from 20 min to 8 hr using curcumin at 0.1% and turmeric at 1%. Unfortunately, fried potato chips treated with gallic acid and green tea increased the final acrylamide. Biological results indicated that acrylamide alone significantly increased serum total cholesterol , triglycerides, LDL.c and VLDL.c levels and-940-significantly decreased the level of (HDL) comparing to the control group and other treated groups. serum total cholesterol, triglycerides, VLDL and LDL levels decreased with the increase in the concentration of turmeric, curcumin, green tea or gallic acid. While, serum HDL level increased with the increase in the concentration of pervious treatments. Finally treatments with acrylamide together with green tea at 10% showed the best treatment followed by treatment with acrylamide together with curcumin 3%..
... Oxidative stress produced by reactive oxygen species (ROS) plays a significant role(s) in the development of many cancers, including those of the esophagus [21]. One study identified curcumin to exert an antioxidant and an anti-inflammatory effect on esophageal cell lines as a result of induction of the activity of superoxide dismutase-1, a potent antioxidant enzyme, and inhibition of the activity of cyclooxygenase-2, a pro-inflammatory protein, respectively [22]. Another study further expanded upon curcumin's anti-inflammatory role in esophageal tumorigenesis by highlighting its inhibition of nuclear factor (NF)-kB activity and interleukin (IL)-8 mRNA expression [23]. ...
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Gastrointestinal (GI) malignancies account for a large portion of cancers worldwide. Although incidence of esophageal, gastric, and colorectal cancers has decreased in recent years, pancreatic and liver cancer have increased. The mainstay of GI cancer therapy is chemoradiation and surgery. Despite significant medical advancements, diagnosis and therapy for GI cancers remain challenging due to tumor cell resistance to chemoradiotherapy. The tumor’s increased cell signalling due to excessive transcription factor activation and increased stellate cell activity leads to collagen deposition formation of a dense stroma around the tumor, which prevents drugs from reaching the malignant cells. This leads to tumor chemoresistance. To circumvent these difficulties, drug therapy targeting the tumor’s specific microenvironment and the additive anticancer effect of phytochemicals can allow for more effective treatment. This volume will be the first on the market on the topic of phytochemicals and their effect on the tumor microenvironment (TME). TME is an emerging area of research and the book will be a welcome introductory addition to the field.
... However, bioavailability is low due to low solubility, poor stability and other factors; thus, the application of curcumin in food and medicine is limited [8,9]. In order to improve curcumin bioavailability and take advantage of it in functional foods and supplements, several carriers including emulsions [6], protein nanoparticles [7,16], protein nanotubes [8], complex coacervates [9], solid lipid nanoparticles [10], filled hydrogel beads [11], liposomes [12], and casein micelles [13][14][15] have been investigated. This experiment modified isolated and extracted peanut protein with hot alkali to study the impact of pH, heating temperature, processing time and other alkali liquor conditions on the molecular structure of the peanut protein and the embedding rate of curcumin. ...
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This study aimed to modify isolated and extracted peanut protein with hot alkali to study the impact of pH, heating temperature, processing time and other alkali liquor conditions on the molecular structure of the peanut.Curcumin was loaded in modified peanut protein.The results of the study are as follows:Within the alkaline range of 8 < pH < 12, the percentage of amino acid residue (AAR) and β-turns first increased and then decreased with the increasing pH, and the percentage of AAR reached a maximum 5.21 ± 0.33% when the pH was 11 (p<0.01). The percentage of α-helices and β-sheets gradually decreased with increasing pH, while that of random coils gradually increased with increasing pH, reaching a maximum 11.24 ± 0.87% when the pH was 11(p<0.05). Within the range of the heating temperature 75 °C < T < 95 °C, the percentage of random coils and β-sheets gradually increased with increasing heating temperature, while that of α-helices and AAR gradually decreased with increasing heating temperature; they remained unchanged when the heating temperature was 90 °C, and then decreased to (10.41 ± 1.18%; p<0.01) and (4.02 ± 2.12%; p<0.01), respectively. Within the range of 5 min < t<20 min, the percentage of random coils and AAR gradually increased with increasing heating time, while the percentage of α-helices decreased from 11.83 ± 1.04% to 10.75 ± 2.34% with increased heating time (p<0.01). The optimum conditions for hot alkali modification of peanut protein as followed: heating temperature of 90 °C, heating time of 20 min and a pH of alkali liquor of 11. Under these optimum conditions, the embedding rate of curcumin by the modified protein can reach 88.32 ± 1.29%.
... Chemoprotective activity: Curcumin activate the DDR (DNA damage response), providing an opportunity and rationale for the clinical application of these nutraceuticals in the chemoprevention of prostate cancer [32]. Chemoprotective effects in esophageal epithelial cells exposed to bile acids; Curcumin reverses bile acid suppression of gene expression of SOD-1 and also able to inhibit bile acid induction of COX-2 gene expression [33]. Curcumin has demonstrated these chemopreventive properties in cell cultures, animal models and human investigations [34]. ...
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Turmeric (Curcuma longa Linn) is extensively used as a spice and grown widely throughout Indian subcontinent. Turmeric plant has been used in traditional medicine as a remedy for various diseases including cough, diabetes and hepatic disorders. For the last few decades, extensive works have been done to establish the pharmacological actions of Turmeric and its extracts. Curcumin is the main chemical compound of Turmeric and proven for its anti-inflammatory, antioxidant, antimutagenic, antidiabetic, antibacterial, hepatoprotective, expectorant and anticancerous pharmacological activities. This review gives update mainly on the pharmacological activities of the Turmeric, its extracts and plausible medicinal applications of Turmeric along with their safety evaluation.
ead the full text About Share on Abstract Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.
Cancer metastasis is a multistage phenomenon, which can be prevented by the administration of various phytochemicals. Phytochemicals inhibit or prevent cancer initiation, promotion, progression, as well as metastasis by employing antioxidant, anti-inflammatory effects mediated via NF-kκB, Nrf2, and AP-1 signaling. Besides, phytochemicals also mediate apoptosis in tumor cells and inhibition of cancer growth. The dietary phytochemicals are abundant in fruits and vegetables that appear to be consisting of beneficial effects against cancer metastasis and induce apoptosis and arrest cell growth by multiple mechanisms.
Malignant cancer is yet one of the overwhelming reasons for mortality and morbidity in the world. Previous literature indicates that a higher intake of fruit and vegetables is correlated with a lower incidence of various types of cancers. The predominant phytochemicals including curcumin, isothiocyanate, genistein, resveratrol, epigallocatechin gallate, and lycopene have been shown to have potential antioxidant, chemopreventive, and anticancer properties. Recent studies demonstrated numerous phytochemicals reported to have antiangiogenic, anticancer, antiproliferative, anti-metastatic, and pro-apoptotic properties. Various animal and cellular studies reveal that these phytochemicals mediate cell death and block cell cycle by numerous mechanisms. The chemopreventive, apoptotic, and anticancer properties of these phytochemicals are results from their use in monotherapy or coalition with immune checkpoint inhibitors or chemotherapeutic drugs. However, despite emerging evidence from various reports, only a few clinical trials are in progress to evaluate the therapeutic effectiveness of these phytochemicals.
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Pancreatic cancer is almost always lethal, and the only U.S. Food and Drug Administration-approved therapies for it, gemcitabine and erlotinib, produce objective responses in <10% of patients. We evaluated the clinical biological effects of curcumin (diferuloylmethane), a plant-derived dietary ingredient with potent nuclear factor-kappaB (NF-kappaB) and tumor inhibitory properties, against advanced pancreatic cancer. Patients received 8 g curcumin by mouth daily until disease progression, with restaging every 2 months. Serum cytokine levels for interleukin (IL)-6, IL-8, IL-10, and IL-1 receptor antagonists and peripheral blood mononuclear cell expression of NF-kappaB and cyclooxygenase-2 were monitored. Twenty-five patients were enrolled, with 21 evaluable for response. Circulating curcumin was detectable as drug in glucuronide and sulfate conjugate forms, albeit at low steady-state levels, suggesting poor oral bioavailability. Two patients showed clinical biological activity. One had ongoing stable disease for >18 months; interestingly, one additional patient had a brief, but marked, tumor regression (73%) accompanied by significant increases (4- to 35-fold) in serum cytokine levels (IL-6, IL-8, IL-10, and IL-1 receptor antagonists). No toxicities were observed. Curcumin down-regulated expression of NF-kappaB, cyclooxygenase-2, and phosphorylated signal transducer and activator of transcription 3 in peripheral blood mononuclear cells from patients (most of whom had baseline levels considerably higher than those found in healthy volunteers). Whereas there was considerable interpatient variation in plasma curcumin levels, drug levels peaked at 22 to 41 ng/mL and remained relatively constant over the first 4 weeks. Oral curcumin is well tolerated and, despite its limited absorption, has biological activity in some patients with pancreatic cancer.
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Human esophageal epithelial cells play a key role in esophageal inflammation in response to acidic pH during gastroesophageal reflux disease (GERD), increasing secretion of IL-6 and IL-8. The mechanisms underlying IL-6 and IL-8 expression and secretion in esophageal epithelial cells after acid stimulation are not well characterized. We investigated the role of PKC, MAPK, and NF-kappaB signaling pathways and transcriptional regulation of IL-6 and IL-8 expression in HET-1A cells exposed to acid. Exposure of HET-1A cells to pH 4.5 induced NF-kappaB activity and enhanced IL-6 and IL-8 secretion and mRNA and protein expression. Acid stimulation of HET-1A cells also resulted in activation of MAPKs and PKC (alpha and epsilon). Curcumin, as well as inhibitors of NF-kappaB (SN-50), PKC (chelerythrine), and p44/42 MAPK (PD-098059) abolished the acid-induced expression of IL-6 and IL-8. The JNK inhibitor SP-600125 blocked expression/secretion of IL-6 but only partially attenuated IL-8 expression. The p38 MAPK inhibitor SB-203580 did not inhibit IL-6 expression but exerted a stronger inhibitory effect on IL-8 expression. Together, these data demonstrate that 1) acid is a potent inducer of IL-6 and IL-8 production in HET-1A cells; 2) MAPK and PKC signaling play a key regulatory role in acid-mediated IL-6 and IL-8 expression via NF-kappaB activation; and 3) the anti-inflammatory plant compound curcumin inhibits esophageal activation in response to acid. Thus IL-6 and IL-8 expression by acid may contribute to the pathobiology of mucosal injury in GERD, and inhibition of the NF-kappaB/proinflammatory cytokine pathways may emerge as important therapeutic targets for treatment of esophageal inflammation.
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Normal human esophageal autopsy tissue was explanted in serum-free medium. The epithelial outgrowths were subcultured and then transfected by strontium phosphate coprecipitation with plasmid pRSV-T consisting of the RSV-LTR promoter and the sequence encoding the simian virus 40 large T-antigen. The transfected cells, but not the sham-transfected controls, formed multilayered colonies within 3-4 weeks, after which the colonies were transferred and cell strains (HE-451 and HE-457) developed. Both cell strains grew exponentially for 8-10 weeks and then senesced. After a "crisis" of 6-8 months, growth resumed in isolated colonies. One line, HET-1A from HE-457, was developed and has now undergone more than 250 population doublings. This line has retained epithelial morphology, stains positively for cytokeratins and the simian virus 40 T-antigen gene by immunofluorescence, and has remained nontumorigenic in athymic, nude mice for more than 12 months. Karyotypic analysis by Giemsa banding has shown that HET-1A is hypodiploid (34-40 chromosomes). Growth factor studies have shown that HET-1A is stimulated by Ca2+, and inhibited by fetal bovine serum, transforming growth factor-beta 1, and transforming growth factor-beta 2. This serum-free immortalized esophageal cell system will be useful for investigating the action of putative esophageal carcinogens.
Previous studies have demonstrated a decrease in manganese superoxide dismutase (MnSOD) in both Barrett's epithelium of patients and columnar esophageal epithelium of rats after esophagoduodenal anastomosis (EDA). Curcuma aromatica, an herbal medicine, has been shown to display anti-carcinogenic properties in a wide variety of cell lines and animals. This study was designed to investigate the ability of Curcuma aromatica oil for the prevention of BE and EAC, possibly through its ability to preserve MnSOD function. EDA was performed on rats and Curcuma aromatica oil was administered by i.p. injection. Histological changes and oxidative damage were determined after EDA of 1, 3, and 6 months. MnSOD protein level and MnSOD enzymatic activity were evaluated. Lipid peroxidation was determined by TBARs assay and 8-hydroxy-deoxyguanosine for DNA oxidative damage was measured by immunohistochemical staining. In addition, the indexes of both apoptosis and proliferation were determined by PCNA staining and TUNEL assay, respectively. Severe esophagitis were seen in EDA rats, and morphological transformation within the esophageal epithelium was observed with intestinal metaplasia and EAC identified after 3 months. The EDA rats treated with Curcuma aromatica oil showed that both MnSOD enzymatic activity and protein level were similar to sham controls. Decreased incidences of intestinal metaplasia and EAC also were observed in the EDA rats with Curcuma aromatica oil treatment. Curcuma aromatica oil prevented loss of MnSOD in EDA rat esophageal epithelium, and this preservation of MnSOD is associated with the potential protective mechanism against transformation of esophageal epithelial to BE to EAC.
Nine human tumor cell lines derived from both epithelial and mesenchymal tumors exhibited either an anchorage-independent growth non-tumorigenic phenotype or an anchorage-independent tumorigenic phenotype. Transformed epithelial cell lines with the non-tumorigenic phenotype could be converted to a progressively growing tumor phenotype following treatment with either methylmethane sulfonate (MMS) or N-methyl-N'-nitro-N-nitro-soguanidine (MNNG). In contrast, sarcoma derived cell lines with a non-tumorigenic phenotype could be converted to a progressively growing tumor phenotype only with MNNG. SV40 immortalized HET-1A non-tumorigenic phenotype cells could be converted to a progressively growing tumorigenic phenotype, infrequently, when treated with MNNG, but not MMS. Progressively growing tumors produced by either MMS or MNNG treated non-tumorigenic phenotypes exhibited metastatic potential in nude mice. Chemically treated HET-1A cells acquired the ability to produce tumor in mice but the tumor did not exhibit metastatic potential. In contrast, populations of tumorigenic cells were not rendered more biologically aggressive after treatment with either MMS or MNNG; i.e., the latency period for tumor development was not accelerated and the tumors did not exhibit metastatic potential. These results suggest that the biological effects of MMS and MNNG on non-tumorigenic, tumorigenic and immortalized cell lines are phenotype specific.
A tetrazolium salt has been used to develop a quantitative colorimetric assay for mammalian cell survival and proliferation. The assay detects living, but not dead cells and the signal generated is dependent on the degree of activation of the cells. This method can therefore be used to measure cytotoxicity, proliferation or activation. The results can be read on a multiwell scanning spectrophotometer (ELISA reader) and show a high degree of precision. No washing steps are used in the assay. The main advantages of the colorimetric assay are its rapidity and precision, and the lack of any radioisotope. We have used the assay to measure proliferative lymphokines, mitogen stimulations and complement-mediated lysis.
Oxidative stress in reflux esophagitis was investigated before and after antireflux surgery. Oxidative stress was studied in the distal and proximal esophagus of control patients (without esophagitis, but with other gastrointestinal disorders), of patients with various grades of esophagitis (including Barrett's esophagus), and in patients who had a Nissen fundoplication. Oxidative stress was assessed by chemiluminescence, lipid peroxidation (LP), and by measuring superoxide dismutase (SOD). Chemiluminescence and LP increased with the degree of esophagitis and was highest in patients with Barrett's esophagus; SOD decreased with damage, except in cases of Barrett's esophagus associated with mild esophagitis. Chemiluminescence and LP in reflux patients were higher in the distal than in the proximal esophagus, and SOD was lower, whereas no such difference was found in controls. Findings after Nissen fundoplication were similar to those of controls. Reflux esophagitis is mediated by free radicals depleting SOD. Barrett's esophagus is a severe form of oxidative damage; in some patients, high SOD levels may prevent severe esophagitis. Antireflux surgery prevents oxidative damage.
The mechanisms causing liver injury in cholestatic diseases are unclear. The hypothesis that accumulation of hydrophobic bile acids in hepatocytes during cholestasis leads to generation of oxygen free radicals and oxidative injury was tested. The aim of this study was to determine if hydrophobic bile acid toxicity is associated with increased hydroperoxide generation in isolated rat hepatocytes and mitochondria. Hepatocytes were exposed to taurochenodeoxycholic acid (TCDC; 0-2000 mumol/L) or taurocholic acid (TC; 1000 mumol/L), and cellular injury, intracellular hydroperoxide generation, and thiobarbituric acid-reacting substances (TBARS) were measured. Isolated mitochondria were incubated with 400 mumol/L chenodeoxycholic acid or 400 mumol/L cholic acid, and hydroperoxide generation was measured fluorometrically. Hepatocyte injury, hydroperoxide generation, and TBARS increased over 4 hours on exposure to TCDC but not TC. Hydroperoxide generation preceded hepatocyte injury and accumulation of TBARS. Preincubation of hepatocytes with the antioxidant, d-alpha-tocopheryl succinate, completely abrogated cellular injury, hydroperoxide, and TBARS generation. Hydroperoxide generation was increased in mitochondria exposed to chenodeoxycholic acid. Intracellular generation of hydroperoxides by mitochondria appears to be an early event in hydrophobic bile acid-induced hepatocyte toxicity. Antioxidants may be of benefit in cholestasis.