Article

Increased caveolin-1 expression associated with prolonged overall survival rate in hepatocellular carcinoma

Department of Pathology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.
Pathology (Impact Factor: 2.19). 08/2010; 42(5):438-45. DOI: 10.3109/00313025.2010.494293
Source: PubMed

ABSTRACT

Recent study indicates that the binding of caveolin-1 (CAV1), the essential constituent of caveolae, to endothelial nitric oxide synthase (eNOS) prevents nitric oxide (NO) production in cirrhotic human liver. However, their interplay in hepatocellular carcinoma (HCC) remains undetermined.
Paraffin-embedded sections from 73 HCC patients were included in this study. The expression patterns of CAV1 and eNOS determined by immunohistochemistry were correlated with the clinicopathological characteristics and overall survival.
Although CAV1 expression did not correlate with any clinicopathological characteristic, increased CAV1 expression was associated with prolonged overall survival (p = 0.021), even when using the multivariate Cox's regression model (OR = 0.25, 95%CI = 0.08-0.72, p = 0.011). eNOS expression was correlated with an increased histological grade (p = 0.002) and intriguingly, the patients had a decreased overall survival when their lesions presented with high eNOS but low CAV1 expression concomitantly (p = 0.003). Meanwhile, the increased CAV1/eNOS merged level determined by immunofluorescence was significantly associated with a decreased histological grade and better overall survival (p = 0.023 and 0.001, respectively).
Our results suggest CAV1 may play a tumour-suppressive role and can serve as a predictive biomarker in HCC. The impacts of CAV1 on hepatocarcinogenesis may occur partly through its modulation of eNOS.

Full-text

Available from: Yao-Tsung Yeh, Feb 04, 2015
ANATOMICAL PATHOLOGY
Increased caveolin-1 expression associated with prolonged overall
survival rate in hepatocellular carcinoma
SHEAU-FANG YANG*{x,JIA-YING YANG{,CHU-HO HUANGx,SHEN-NIEN WANG{k,
C
HIA-PEI LU{,CHIA-JUNG TSAI{{,CHEE-YIN CHAI{x** AND YAO-TSUNG YEH{**
*Department of Pathology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, {Department of Pathology,
Faculty of Medicine, College of Medicine, and {Graduate Institute of Medicine, Kaohsiung Medical University,
Kaohsiung, xDepartment of Pathology, and kDepartment of Surgery, Kaohsiung Medical University Hospital,
Kaohsiung, and {Department of Medical Technology, Fooyin University, Kaohsiung County, Taiwan; **these
authors contributed equally to this work
Summary
Aims: Recent study indicates that the binding of caveolin-1
(CAV1), the essential constituent of caveolae, to endothelial
nitric oxide synthase (eNOS) prevents nitric oxide (NO)
production in cirrhotic human liver. However, their interplay in
hepatocellular carcinoma (HCC) remains undetermined.
Methods: Paraffin-embedded sections from 73 HCC patients
were included in this study. The expression patterns of CAV1
and eNOS determined by immunohistochemistry were
correlated with the clinicopathological characteristics and
overall survival.
Results: Although CAV1 expression did not correlate with
any clinicopathological characteristic, increased CAV1 ex-
pression was associated with prolonged overall survival
(p ¼ 0.021), even when using the multivariate Cox’s regres-
sion model (OR ¼ 0.25, 95%CI ¼ 0.08–0.72, p ¼ 0.011).
eNOS expression was correlated with an increased histolo-
gical grade (p ¼ 0.002) and intriguingly, the patients had a
decreased overall survival when their lesions presented with
high eNOS but low CAV1 expression concomitantly
(p ¼ 0.003). Meanwhile, the increased CAV1/eNOS merged
level determined by immunofluorescence was significantly
associated with a decreased histological grade and better
overall survival (p ¼ 0.023 and 0.001, respectively).
Conclusions: Our results suggest CAV1 may play a tumour-
suppressive role and can serve as a predictive biomarker in
HCC. The impacts of CAV1 on hepatocarcinogenesis may
occur partly through its modulation of eNOS.
Key words: Caveolin-1, endothelial nitric oxide synthase, hepatocellular
carcinoma.
Abbreviations: CAV1, caveolin- 1; HCC, hepatocellular carcinoma; eNOS,
endothelial nitric oxide synthase; NO, nitric oxide; EGF, epidermal growth
factor.
Received 9 January, revised 16 March, accepted 28 March 2010
INTRODUCTION
Caveolin-1 (CAV1) is the essential constituent of caveolae,
flask-shaped invaginations occupying up to 20% of the
plasma membrane,
1–3
in which CAV1 mediates endocytosis
and transcytosis of molecules attached to the cell surface and
organises signalling proteins involved in cell proliferation,
adhesion and migration.
4
Intriguingly, CAV1 can be a
tumour suppressor or initiator, depending on the tissue of
origin and stage of the disease.
2,5–7
For example, CAV1
serves as a tumour suppressor in small cell lung cancer but is
required for survival and growth in non-small cell lung
cancer.
8
In addition, loss of CAV1 promoted metastasis in a
tumour progression model of breast cancer, and disruption
of the CAV1 gene in transgenic mice promoted mammary
tumorigenesis and increased formation of metastases.
9
There is a lack of information regarding the distribution
and clinical implications of CAV1 in hepatocellular carci-
noma (HCC). In the liver, CAV1 is essential in regulating
liver regeneration through its modulation of triglyceride
accumulation,
8
suggesting CAV1 may contribute to pro-
liferation of the liver cells. On the other hand, enhanced
CAV1 expression appears to be associated with a signifi-
cantly reduced nitric oxide (NO) catalytic activity in the
cirrhotic liver.
11
These observations imply altered CAV1
expression may contribute to hepatocarcinogenesis.
Endothelial nitric oxide synthase (eNOS) is a lipid-
modified protein found in the caveolae, where eNOS
interacts with CAV1.
10,12
As a consequence, the eNOS
catalytic activity is inhibited, preventing NO production.
13
NO is a labile free radical gas functioning as a signaller and
effector in the control of various cellular functions.
14
Mounting evidence has demonstrated the production of
NO is critical in the angiogenic process.
15–17
In addition,
eNOS is required to initiate and maintain tumour growth
in vivo.
18
However, controversially, mice with an eNOS
deficiency develop liver tumours more frequently in response
to carcinogens compared with control animals, but eNOS
overexpression in the tumour microenvironment attenuated
both the number and size of tumour implants in a surgical
model of pancreatic cancer liver metastasis.
19
In the cirrhotic
human liver, marked increase of CAV1 in perisinusoidal
cells may promote CAV1-eNOS binding and reduce the
activity of eNOS leading to impaired NO production and
increased hepatic microvascular tone despite increased
eNOS expression.
20
The study suggests alteration of the
Pathology (August 2010) 42(5), pp. 438–445
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associated proteins of eNOS such as CAV1 may play a role
in HCC development.
In the present study, we aimed to analyse the distribution
of CAV1 and eNOS1 as well as their interplay in HCC. We
used immunofluorescence and immunoprecipitation to
monitor the potential interaction between CAV1 and eNOS
protein and also to explore their clinical significance in HCC.
Here, we show for the first time that CAV1 may play a
tumour suppressive role in HCC, in part through its
modulation of eNOS.
MATERIALS AND METHODS
Surgical specimens
Seventy-three surgically resected HCCs were obtained from the Depart-
ment of Surgery, Kaohsiung Medical University Hospital, Kaohsiung,
Taiwan, between January 1995 and December 2003. For the purposes of
this study, 73 cases (57 men and 16 women; mean age 57.3 years; range 30–
83 years) that met the following criteria were included: (1) curative
hepatectomy; (2) absence of prior treatment, such as transarterial
chemoembolisation and percutaneous ethanol injection therapy; and (3)
no apparent distant metastases. All patients were followed up for a mean
period (39.04 months; range 0.4–111.6 months). The specimens were
routinely fixed in 10% buffered formalin and embedded in paraffin wax.
Clinicopathological parameters including age, gender, recurrence (pre-
sent or absent), histological grading (well/moderately differentiated versus
poorly differentiated), tumour stage (I/II versus III/IV) and vascular
invasion (including vascular invasion and/or tumour thrombi in the portal
or hepatic vein) were retrospectively recorded. Histological grading and
staging was according to the World Health Organization histological
classification and the pathological tumour-node-metastases classification,
respectively.
21
Immunohistochemistry
The samples were sliced to a thickness of 3 mm, and then harvested with the
primary antibodies, followed by Universal LABþ kit/HRP (Dako, Den-
mark) and counterstained with haematoxylin.
22
The results were captured
by a Nikon E-800M microscope (Nikon, Japan), and then processed by
Kodak MGDS330 (Kodak, USA) and Adobe Photoshop 6.0 (Adobe,
USA).
The intensity of CAV1 and eNOS immunostaining in the HCC lesions
was graded by a semi-quantitative system: low expression (negative/weak)
and high expression (moderate/strong). More than 1000 cells expressed in
3–4 different high power fields (HPF; 6200) were analysed for each section.
The immunostaining for CAV1 and eNOS were determined separately for
each specimen and estimated by two independent pathologists. The rare
cases with discordant scores were re-evaluate d and scored based on a
consensus opinion.
23
Immunofluorescence staining
The samples were sliced to a thickness of 3 mm, and then harvested with the
mouse anti-human CAV1 (1:200; Santa Cruz, USA) and rabbit anti-human
eNOS (1:25; Transduction/BD, USA) antibodies, washed, and incubated
with FITC-labelled rabbit anti-mouse (1:100) and Texas Red-labelled rat
anti-rabbit (1:40) antibodies, respectively. Images were analysed with an
Olympus fluorescence microscope (Olympus, Japan) coupled to a digital
camera under identical acquisition parameters.
24
The merged frequency of CAV1 and eNOS immunofluorescence
staining in HCC lesions was graded by a semi-quantitative system: low
expression (10%) and high expression (410). More than 1000 cells
expressed in 3–4 different HPF (6200) were analysed for each section. The
immunostaining for CAV1 and eNOS was determined separately for each
specimen and estimated by two independent pathologists. The rare cases
with discordant scores were re-evaluated and scored based on a consensus
opinion.
23
Immunoprecipitation assay
The protein extracts of the HCC cells and paired tissues were prepared
using EBC buffer (50 mM Tris pH 7.6, 120 mM NaCl, 0.5% Nonidet P-40,
1 mM EDTA, 1 mM 2-mercaptoethanol, 50 mM NaF, 1 mM Na3VO4).
24
Preclearing was performed twice with uncoated protein G-sepharose beads
(Santa Cruz), and the supernatant was incubated with rabbit polyclonal
anti-eNOS antibodies (Transduction/BD). Immune com plexes were pre-
cipitated with protein G-sepharose beads and 50 mL of supernatant (SNT)
was added to the Laemmli solution and processed for SDS-PAGE. CAV1
and eNOS signals were revealed with monoclonal anti-eNOS (1:1500;
Transduction/BD) and anti-CAV1 (1:15 000; Santa Cruz) antibodies.
Immunoblotting analysis
Total lyses of Hep-G2 cells treated with EGF (20 ng/mL) for 24 h in serum-
free medium were extracted by EBC buffer. Similarly, the frozen tissue
specimens were ground up and dissolved in EBC buffer. The detailed
procedures for immunoblotting were followed accordingly.
25
Rabbit
polyclonal anti-eNOS antibody and mouse monoclonal anti-CAV1 were
obtained from Transduction/BD and Santa Cruz, respectively. Mouse
monoclonal anti-b-actin was obtained from Sigma (Sigma, USA). For
comparing the expression levels of CAV1 and eNOS in cancer versus non-
cancer tissues, the AlphaImager 1220 documentation and analysis system
was used (Alpha Innotech, USA).
Statistical analysis
The statistical analyses were performed using the SPSS 10.0 statistical
package for PC (SPSS, USA). Single-variable analyses were performed
using the two-tailed Student’s t test and w
2
test, and confirmed by Fisher’s
exact test. Groups of patients with different CAV1 and eNOS expression
levels were correlated with gender, tumour stage, tumour grade, vascular
invasion, recurrence, viral markers, using Spearman’s rho coefficient
analysis and Fisher’s exact test. Survival curves were calculated using the
Kaplan-Meier method and the significance was determined by log rank test.
Table 1 Clinicopathological characteristics of hepatocellular carcinoma
patients
Characteristics n Patients (%)
Gender
Female 16 21.9
Male 57 78.1
Histological grade
I 11 15.1
II 51 69.9
III 11 15.1
Tumour stage
I 15 20.5
II 38 52.1
III 17 23.3
IV 3 4.1
Vascular invasion
Present 23 31.5
Absent 50 68.5
Recurrence
Present 31 42.5
Absent 42 57.5
Viral marker
HBV(7)/HCV(7)6 8.2
HBV(þ)/HCV(7) 42 57.5
HBV(7)/HCV(þ) 17 23.3
HBV(þ)/HCV(þ) 8 11.0
CAV1
High expression 55 75.3
Low expression 18 24.7
eNOS
High expression 39 53.4
Low expression 34 46.6
(þ), positive or present; (7), negative or absent; HBV, hepatitis B surface
antigen; HCV, anti-hepatitis C virus antibody.
INTERPLAY OF CAV-1 WITH eNOS IN HCC 439
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Multivariate OR was calculated using the Cox proportional hazards
regression model. A value of p 0.05 was considered significant.
22,26,27
RESULTS
Expression profiles of CAV1 and eNOS in HCC lesions
The clinicopathological characteristics of HCC patients
included in this study are shown in Table 1. To examine
the potential involvement and distribution pattern of
CAV1 and eNOS protein in HCC, immunohisto-
chemistry was first applied. CAV1 was dominantly
localised in the vascular endothelium surrounding the
lesions, in which eNOS was diffused in the cytoplasm of
tumour cells (Fig. 1). Intense CAV1 and eNOS staining
was noted in 75.3% and 53.4% of HCC lesions,
respectively (Table 1).
Fig. 1 Scoring systems of CAV1 and eNOS immunostaining in HCC lesions. The cytoplasmic intensity of CAV1 and eNOS immunostaining in HCC lesions
was categorised by a semi-quantitative system: low expression (negative and weak staining) and high expression (moderate and strong staining). More than
1000 cells expressed in 3*4 different high power fields (6200) were analysed for each section.
Table 2 The correlation of eNOS and CAV1 intensity with clinicopathological characteristics in hepatocellular carcinoma tissues
Characteristics
eNOS CAV1 Merged eNOS and CAV1
Low (n ¼ 34) High (n ¼ 39) p value Low (n ¼ 18) High (n ¼ 55) p value Low (n ¼ 24) High (n ¼ 49) p value
Gender 0.801 0.207 0.661
Female 7 9 2 14 6 10
Male 2730 1641 1839
Histological grade 0.002 0.999 0.023
I 7429110
II 27 24 14 37 17 34
III 0 11 2 9 6 5
Tumour stage 0.895 0.137 0.195
I96411411
II 14 24 5 33 11 27
III 10 7 8 9 7 10
IV 12 12 21
Vascular invasion 0.394 0.178 0.196
Present 9 14 8 15 10 3
Absent 25 25 10 40 14 36
Recurrence 0.793 0.463 0.369
Present 15 16 9 22 12 19
Absent 19 23 9 33 12 30
Viral marker 0.328 0.272 0.166
HBV(7)/HCV(7)241515
HBV(þ)/HCV(7)1824 1329 1329
HBV(7)/HCV(þ)11 6 4 13 5 12
HBV(þ)/HCV(þ)350853
Data were determined by Spearman’s coefficient test.
(þ), positive or present; (7), negative or absent; HBV, hepatitis B surface antigen; HCV, anti-hepatitis C virus antibody.
440 YANG et al. Pathology (2010), 42(5), August
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Correlation of CAV1 and eNOS expression with
clinicopathological parameters in HCC
To explore whether alterations of CAV1 and eNOS
proteins correlated with HCC progression, the patterns
obtained were further correlated with the clinicopathologi-
cal characteristics (Table 2). Unexpectedly, CAV1 expres-
sion had no significant correlation with gender, histological
grade, tumour stage, vascular invasion, and viral markers
in the patients we analysed (Table 2). Increased eNOS
expression was only correlated with an increased histolo-
gical grading (Table 2; p ¼ 0.002).
Correlation of CAV1 and eNOS expression with the overall
survival of HCC patients
The Kaplan-Meier survival curve showed the high CAV1
expression group was significantly associated with a better
overall survival rate over thelow CAV1 expression group(Fig.
2A; p ¼ 0.021). Although there was no significant difference in
the overall survival rate between the low and high expression
groups of eNOS (Fig. 2B; p ¼ 0.163), the patients with high
eNOS expression in the low CAV1 expression group (Fig. 2C;
p ¼ 0.003), but not in the high CAV1 expression group (Fig.
2D; p ¼ 0.746), had a poorer overall survival rate. When a
multivariate Cox’s proportional hazards model was used,
both CAV1 and eNOS expression were found to be significant
determinants of the overall survival rate for HCC patients
(Table 3; p ¼ 0.011 and 0.016, respectively).
Interaction of CAV1 and eNOS in HCC tissues
Current studies reveal CAV1 interacts with eNOS in several
organisms and attenuates eNOS activity.
28–30
Thus, we
Fig. 2 Overall survival rate of the HCC patients in different expression groups. (A) and (B) show overall survival rate of low and high cytoplasmic intensity of
eNOS and CAV1, and (C) and (D) show the patients with low and high eNOS intensity in different CAV1 expression groups. The Kaplan-Meier method was
used to determine the differences in patient survival between subgroups and the significance was determined by log rank test.
Table 3 Multivariate Cox regression analysis of overall survival of the
HCC cases
Variables OR 95%CI p
Age (450/50 years) 0.79 0.25–2.50 0.691
Tumour size (cm) 1.17 0.97–1.42 0.100
Tumour stage ( I, II, III, IV) 2.40 1.15–5.04 0.020
Histological grade ( I, II, III) 1.33 0.50–3.51 0.571
Vascular invasion (absent and present) 3.49 1.28–9.52 0.014
Viral marker (7/7, þ/7, 7/þ, þ/þ) 0.93 0.48–1.83 0.838
eNOS (low and high) 4.39 1.32–14.55 0.016
CAV1 (low and high) 0.25 0.08–0.72 0.011
Data are determined by Cox proportional hazards regression.
7/7 ,HBV(7)/HCV(7); þ/7,HBV(þ)/HCV(7); 7/þ,HBV(7)/
HCV(þ); þ/þ, HBV(þ)/HCV(þ); CI, confidence interval; HBV, hepatitis
B surface antigen; HCV, anti-hepatitis C virus antibody; OR, odds ratio.
INTERPLAY OF CAV-1 WITH eNOS IN HCC 441
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examined whether the interaction between CAV1 and
eNOS existed in the liver tissues and could be altered
during HCC development. Interestingly, immunoprecipita-
tion showed the interaction between CAV1 and eNOS
protein decreased in the cancerous liver tissues compared
with the matched non-cancer liver tissues (Fig. 3A).
Although limited cases were analysed, the interactions
between CAV1 and eNOS were corresponsive to the
frequency of their merged images determined by immuno-
fluorescence in HCC lesions (Fig. 3B). Immunofluorescence
study showed increased levels of the merged images of
CAV1 and eNOS protein were noted in 67.1% of HCC
lesions (Fig. 4). Interestingly, the HCC patients with
increased levels of the merged images of CAV1 and eNOS
protein had a significantly decreased histological grading
(Table 2; p ¼ 0.023). In addition, decreased levels of the
merged images of CAV1 and eNOS were significantly
associated with a poor overall survival rate in our cases
(Fig. 5, p ¼ 0.001).
DISCUSSION
CAV1, the essential constituent of caveolae, has been
implicated as a tumour suppressor or initiator, depending
on the tissue of origin.
2,5–7
In HCC, our observations show
for the first time that CAV1 may play a tumour suppressive
role through its modulation of eNOS in part. More
importantly, both CAV1 and eNOS expression can be
significant determinants for patient survival of HCC.
In the present study, CAV1 expression was significantly
associated with the overall survival rate, when using
multivariate Cox’s proportional hazards model, implicating
its tumour suppressive potential in HCC. However, CAV1
expression was increased but was not significantly corre-
lated with patient characteristics, suggesting CAV1 might
not directly contribute to specific tumour behaviours but
may possibly cooperate by other effectors in HCC. In our
cases, CAV1 might bind to eNOS and counter eNOS
activity.
Intriguingly, mice with an eNOS deficiency developed
liver tumours more often in response to carcinogens
compared with control animals.
19
Inconsistently, our
results showed an intense eNOS staining in 53.4% of the
HCC lesions and was correlated with increased histological
grading, suggesting eNOS in human subjects might
contribute to HCC. In addition, the nature of HCC
development may be more complex and differ from
carcinogen-induced carcinogenesis. Similarly, overexpres-
sion of eNOS in astrocytic tumours is found to be
correlated with histological grade according to our
observations.
28
We also found eNOS expression was
negative for prolonged patient survival using multivariate
Fig. 3 Immunoprecipitation (IP) analysis of the protein-protein interaction between CAV1 and eNOS in HepG2 cells as well as the paired cancerous and
non-cancerous liver tissues. (A) Immunoprecipitation (IP) analysis was performed in Hep-G2 cells treated with EGF (20 ng/mL) for 24 h as well as the paired
cancerous and non-cancer liver tissues. Cell and tissues lyses were immunoprecipitated with eNOS-specific antibody and immunoblotted with the antibodies
specifically against CAV1 and eNOS. (B) The merged frequency of CAV1 and eNOS were determined by immunofluorescence staining and presented as
mean + SD. C, control; E, EGF; N, non-cancer liver tissues; No., number; P, patient; T, HCC tissu es.
442 YANG et al. Pathology (2010), 42(5), August
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Page 5
Cox’s proportional hazards model. Recently, Lim et al.
have reported that eNOS is required to initiate and
maintain tumour growth,
18
suggesting that under certain
conditions, such as oncogene addition, eNOS may assist in
advanced development or maintenance of tumour growth.
Moreover, high eNOS expression is positively correlated
with tumour cell vascular invasion in human colon cancer
29
and trophoblast cancer cells.
30
eNOS is required for
initiating and maintaining pancreatic cell growth in vivo,
18
and it also attenuates the number and size of tumour
implants of pancreatic cancer liver metastasis.
19
Enhanced CAV1 expression appears to be associated with
significantly reduced NO catalytic activity in the cirrhotic
liver.
10
Current studies have revealed thatCAV1 interactswith
eNOS in several organisms and modulates eNOS activity.
31–33
These studies imply CAV1 can reduce eNOS activity through
their protein-protein interaction. Interestingly, our results
showed there indeed existed an interaction between CAV1 and
eNOS protein and the interaction was predominantly
decreased in the HCC tissues compared with its paired non-
cancer liver tissues. We also found patients with high eNOS
expression had a lower survival rate in the low CAV1
expression group. These results confirmed an increased
CAV1 might counter the positive contribution of eNOS to
HCC. Indeed, decreased/low levels of the merged images of
CAV1 and eNOS were significantly associated with a poor
survival rate. More interestingly, HCC patients with an
increased merged image of CAV1 and eNOS protein had a
significantly decreased histological grading. Consistently,
eNOS expression was correlated with histological grading.
Thus, CAV1 at least decreased the activity of eNOS in
assisting poor progression of HCC. Although we did not find a
significant correlation of CAV1 with the clinicopathological
characteristics of our cases, our finding that increased CAV1
was associated with a better survival rate might be partly
explained by its modulation of eNOS action in HCC. In vivo
studies have shown that overexpression of CAV1 results in
dramatic tumour growth delay through impairing eNOS
activity.
34
However, our results were inconsistent with the
observations in cirrhotic human liver that marked increase of
CAV1 promotes CAV1-eNOS binding and reduces the
activity of eNOS despite increased eNOS expression, leading
to increased hepatic microvascular tone.
20
In the case of the
cirrhotic human liver, increased CAV1 appears to elevate
microvascular tone, possibly leading to poor prognosis and
survival.
Fig. 4 Scoring systems of CAV1 and eNOS immunofluorescence staining in HCC lesions. The cytoplasmic intensity of CAV1 and eNOS immunofluorescence
staining in HCC lesions was categorised a scoring system: low expression (10%) and high expression (410%). More than 1000 cells expressed in 3*4
different high power fields (6200) were analysed for each section.
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It is intriguing to note CAV1 and eNOS can be tumour
suppressors or initiators, depending on the tissue of origin
or stage of disease.
2,5–7,18,19
However, there is a lack of
information concerning their clinical impacts and possible
interplays in HCC. More intriguingly, it is noted that
CAV1-eNOS binding may reduce the activity of eNOS.
20
Here, we show for the first time their distributions and
clinical impacts on HCC. We found that CAV1 was
dominantly increased but was not correlated with any
patient characteristic in HCC cases. Interestingly, increased
CAV1 expression was associated with a better overall
survival, even when using multivariate Cox’s regression
model, suggesting CAV1 might be a tumour suppressor and
may serve as a clinical biomarker and protective determi-
nant of patient survival in HCC.
In the present study, tumour staging, vascular invasion,
and in particular eNOS, were effective determinants of poor
patient survival. A positive correlation was noted between
eNOS and histological grade. Interestingly, concomitant
high eNOS and low CAV1 expression was associated with a
poor survival rate. Meanwhile, increased frequency of the
merged image of CAV1 and eNOS was significantly
associated with decreased tumour grading and better
overall survival rate, respectively. Collectively, our results
suggest that eNOS may contribute to HCC development.
In contrast, CAV1 may be a tumour suppressor in HCC
partly through its modulation of eNOS activity. Further
investigations are required to address these possibilities.
Inhibition of eNOS activity may be a choice in treating
HCC and improving patient survival.
Acknowledgement: This study is partly supported by NSC
grants (NSC 97-2320-B-242-001-MY3 to YT Yeh).
Address for correspondence: Professor Y-T. Yeh, Department of Medical
Technology, Fooyin University, No.151, Jinsyue Rd, Daliao Township,
Kaohsiung County 831, Taiwan (ROC).
E-mail: glycosamine@yahoo.com.tw
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444 YANG et al. Pathology (2010), 42(5), August
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INTERPLAY OF CAV-1 WITH eNOS IN HCC 445
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  • [Show abstract] [Hide abstract] ABSTRACT: Caveolins are a family of membrane-bound scaffolding proteins that compartmentalize and negatively regulate signal transduction. Recent studies have implicated a loss of caveolin-1 (Cav-1) expression in the pathogenesis of human cancers. Loss of Cav-1 expression in cancer-associated fibroblasts results in an activated tumor microenvironment, thereby driving early tumor recurrence, metastasis, and poor clinical outcome in breast and prostate cancers. We describe various paracrine signaling mechanism(s) by which the loss of stromal Cav-1 promotes tumor progression, including fibrosis, extracellular matrix remodeling, and the metabolic/catabolic reprogramming of cancer-associated fibroblast, to fuel the growth of adjacent tumor cells. It appears that oxidative stress is the root cause of initiation of the loss of stromal Cav-1 via autophagy, which provides further impetus for the use of antioxidants in anticancer therapy. Finally, we discuss the functional role of Cav-1 in epithelial cancer cells.
    No preview · Article · Jan 2011 · Annual Review of Pathology Mechanisms of Disease
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    [Show abstract] [Hide abstract] ABSTRACT: Caveolins are the principal protein component of caveolae, plasma membrane invaginations found in most cell types. Caveolin-1 (Cav-1) plays a major role in oncogenesis through its various functions in lipid transport, membrane trafficking, and signal transduction. Increased expression of Cav-1 in tumor cells has been associated with aggressiveness and poor survival. More recently, loss of stromal Cav-1 expression was linked to poor survival and increased metastatic potential in breast and prostate cancer. To date, there is no study addressing the clinical significance of Cav-1 expression in malignant melanoma (MM). Our study consisted of 44 cases of MM: 12 MM lymph node metastases from patients with short survival, 12 MM lymph node metastases from patients with long survival and 20 primary MM. All cases were stained with Cav-1 antibodies. Cav-1 expression in melanoma and stromal cells was quantified using a 3 point scale: 0 = no staining, 1 = diffuse weak staining or strong staining in < 30% of cells, and 2 = diffuse strong staining. A score of 0-1 represented low Cav-1 expression and a score of 2 represented high Cav-1 expression. In patients with MM lymph node metastases, a low stromal Cav-1 expression was associated with shorter survival when compared to the high stromal Cav-1 expression group (median survival 252 days versus 3,508 days, p value 0.0054). Conversely, high Cav-1 expression in melanoma cells was associated with a longer survival in primary MM (p < 0.0001). In conclusion, high expression of stromal Cav-1 correlates with longer survival in malignant melanoma metastases, and high expression of Cav-1 in melanoma cells correlates with longer survival in primary malignant melanoma.
    Full-text · Article · Dec 2011 · Cell cycle (Georgetown, Tex.)
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    [Show abstract] [Hide abstract] ABSTRACT: Heart damage induced by chlorpromazine (CPZ) toxicity is associated with changes in the expression of various enzymes and proteins. This study aimed to investigate CPZ‑induced alterations in cardiac E-cadherin and caveolin-1 (cav-1) after CPZ administration. Male Wistar rats were randomly divided into two groups: a control group and a CPZ group. The CPZ group was administered CPZ intraperitoneally at a single dose of 10 mg/kg for 21 days; the controls were given the same amount of saline via the same route. On Day 22, the rats were anesthetized, and a thoracotomy was performed in all animals. Immunohistochemical analysis was performed to evaluate protein expression of E-cadherin and cav-1. Sections were analyzed by digital image analysis. Results of the present study revealed that cardiac protein expression of E-cadherin and cav-1 was altered after CPZ-induced toxicity in the rat. The expression of E-cadherin was significantly reduced, while expression of cav-1 was significantly increased after CPZ treatment, as supported by integrated optical density analysis, compared with the control (P<0.05). The current findings indicate that such changes in the expression of E-cadherin and cav-1 may be reflected in abnormal cardiac function, and these proteins may be useful in revealing the mechanisms underlying CPZ-induced toxicity and may also provide additional insight for further research.
    Preview · Article · Dec 2011 · Molecular Medicine Reports
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