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ABSTRACT: Aims: The purpose of this study was to investigate the associations of β-catenin mutations, K-ras mutations, methylations of the RASSF1A promoter, and the survival of Taiwanese colorectal cancer (CRC) subjects who received 5-fluorouracil (5-FU) adjuvant chemotherapy. Results: The complete coding region of the K-ras gene and exon 3 and exon 4 of the β-catenin gene isolated from tumor tissues and adjacent normal colon tissues from 117 CRC subjects were sequenced, respectively. Methylations in the RASSF1A promoter region were also investigated. Various characteristics of the 117 subjects were recorded and used in the Cox proportional-hazard model analyses. Three missense mutations, one nonsense mutation, and one deletion were identified in the β-catenin gene. A 2 bp deletion was identified in the K-ras gene. We found that the frequencies of mutations in the β-catenin and K-ras genes were less pronounced in Taiwanese CRC subjects as compared with other populations. Methylations in the RASSF1A promoter region were detected in 73.5% (n=86/117) of the subjects, which was higher than in other studies. Methylations in the RASSF1A promoter have no significant effect on hazards for all CRC deaths caused in Taiwanese CRC patients. No interaction between 5-FU adjuvant chemotherapy and methylations of the RASSF1A promoter was observed. Conclusions: The mutation frequencies of β-catenin and K-ras genes in Taiwanese CRC patients are very low, which may suggest that they are not the dominant factors for CRC occurrence and prognosis in Taiwanese CRC patients. Methylation of RASSF1A promoter is independent of the prognosis for Taiwanese CRC patients. Taiwanese subjects differ from subjects of other populations with regard to β-catenin, K-ras, and RASSF1A presentations for CRC.
Genetic Testing and Molecular Biomarkers 09/2012; · 1.11 Impact Factor
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ABSTRACT: Episodic cessation of airflow during sleep in patients with sleep apnea syndrome results in intermittent hypoxia (IH). Our aim was to investigate the effects of IH on cerebellar granule cells and to identify the mechanism of IH-induced cell death.
Cerebellar granule cells were freshly prepared from neonatal Sprague-Dawley rats. IH was created by culturing the cerebellar granule cells in the incubators with oscillating O2 concentration at 20% and 5% every 30 min for 1-4 days. The results of this study are based on image analysis using a confocal microscope and associated software. Cellular oxidative stress increased with increase in IH. In addition, the occurrence of cell death (apoptosis and necrosis) increased as the duration of IH increased, but decreased in the presence of an iron chelator (phenanthroline) or poly (ADP-ribose) polymerase (PARP) inhibitors [3-aminobenzamide (3-AB) and DPQ]. The fluorescence of caspase-3 remained the same regardless of the duration of IH, and Western blots did not detect activation of caspase-3. However, IH increased the ratio of apoptosis-inducing factor (AIF) translocation to the nucleus, while PARP inhibitors (3-AB) reduced this ratio.
According to our findings, IH increased oxidative stress and subsequently leading to cell death. This effect was at least partially mediated by PARP activation, resulting in ATP depletion, calpain activation leading to AIF translocation to the nucleus.
We suggest that IH induces cell death in rat primary cerebellar granule cells by stimulating oxidative stress PARP-mediated calpain and AIF activation.
Journal of Biomedical Science 03/2012; 19:29. · 2.01 Impact Factor
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ABSTRACT: It is unknown whether human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) can improve the renal function of patients suffering from acute kidney injury. Moreover, before beginning clinical trials, it is necessary to investigate this renoprotective effect of hUC-MSCs in a xenogeneic model of acute kidney injury. However, no previous studies have examined the application of hUC-MSCs to immunodeficient mice suffering from acute kidney injury. The objectives of this study were to examine whether hUC-MSCs could improve renal function in nonobese diabetic-severe combined immune deficiency (NOD-SCID) mice suffering from acute kidney injury, and to investigate the mechanism(s) for hUC-MSCs to improve renal function in this xenogeneic model. Early (3 hr) and late (12 hr) administrations of hUC-MSCs (10(6) cells) were performed via the external jugular vein into NOD-SCID mice suffering from either folic acid (FA) (250 mg/kg body weight) or vehicle. The results showed that early administration of hUC-MSCs improved the renal function of NOD-SCID mice suffering from FA-induced acute kidney injury, as evidenced by decreased serum urea nitrogen and serum creatinine levels, as well as a reduced tubular injury score. The beneficial effects of hUC-MSCs were through reducing apoptosis and promoting proliferation of renal tubular cells. These benefits were independent of inflammatory cytokine effects and transdifferentiation. Furthermore, this study is the first one to show that the reduced apoptosis of renal tubular cells by hUC-MSCs in this xenogeneic model is mediated through the mitochondrial pathway, and through the increase of Akt phosphorylation.
PLoS ONE 01/2012; 7(9):e46504. · 4.09 Impact Factor
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ABSTRACT: N-butylidenephthalide (BP) exhibits antitumor effect in a variety of cancer cell lines. The objective of this study was to obtain additional insights into the mechanisms involved in BP induced cell death in human prostate cancer cells.
Two human prostate cancer cell lines, PC-3 and LNCaP, were treated with BP, and subsequently evaluated for their viability and cell cycle profiles. BP caused cell cycle arrest and cell death in both cell lines. The G0/G1 phase arrest was correlated with increase levels of CDK inhibitors (p16, p21 and p27) and decrease of the checkpoint proteins. To determine the mechanisms of BP-induced growth arrest and cell death in prostate cancer cell lines, we performed a microarray study to identify alterations in gene expression induced by BP in the LNCaP cells. Several BP-induced genes, including the GADD153/CHOP, an endoplasmic reticulum stress (ER stress)-regulated gene, were identified. BP-induced ER stress was evidenced by increased expression of the downstream molecules GRP78/BiP, IRE1-α and GADD153/CHOP in both cell lines. Blockage of IRE1-α or GADD153/CHOP expression by siRNA significantly reduced BP-induced cell death in LNCaP cells. Furthermore, blockage of JNK1/2 signaling by JNK siRNA resulted in decreased expression of IRE1-α and GADD153/CHOP genes, implicating that BP-induced ER stress may be elicited via JNK1/2 signaling in prostate cancer cells. BP also suppressed LNCaP xenograft tumor growth in NOD-SCID mice. It caused 68% reduction in tumor volume after 18 days of treatment.
Our results suggest that BP can cause G0/G1 phase arrest in prostate cancer cells and its cytotoxicity is mediated by ER stress induction. Thus, BP may serve as an anticancer agent by inducing ER stress in prostate cancer.
PLoS ONE 01/2012; 7(3):e33742. · 4.09 Impact Factor
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ABSTRACT: We explored the mechanisms of cell death induced by isochaihulactone treatment in LNCaP cells.
LNCaP cells were treated with isochaihulactone and growth inhibition was assessed. Cell cycle profiles after isochaihulactone treatment were determined by flow cytometry. Expression levels of cell cycle regulatory proteins, caspase 9, caspase 3, and PARP were determined after isochaihulactone treatment. Signaling pathway was verified by inhibitors pre-treatment. Expression levels of early growth response gene 1 (EGR-1) and nonsteroidal anti-inflammatory drug-activated gene 1 (NAG-1) were determined to investigate their role in LNCaP cell death. NAG-1 expression was knocked down by si-NAG-1 siRNA transfection. Rate of cell death and proliferation were obtained by MTT assay.
Isochaihulactone caused cell cycle arrest at G2/M phase in LNCaP cells, which was correlated with an increase of p53 and p21 levels and downregulation of the checkpoint proteins cdc25c, cyclin B1, and cdc2. Bcl-2 phosphorylation and caspase activation were also observed. Isochaihulactone induced phosphorylation of c-Jun-N-terminal kinase (JNK), and JNK inhibitor partially reduced isochaihulactone-induced cell death. Isochaihulactone also induced the expressions of EGR-1 and NAG-1. Expression of NAG-1 was reduced by JNK inhibitor, and knocking down of NAG-1 inhibited isochaihulactone-induced cell death.
Isochaihulactone apparently induces G2/M cell cycle arrest via downregulation of cyclin B1 and cdc2, and induces cellular death by upregulation of NAG-1 via JNK activation in LNCaP cells.
BMC Cancer 01/2011; 11:146. · 3.01 Impact Factor
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ABSTRACT: The correlations between adenomatous polyposis coli (APC) mutations and 5-fluorouracil (5-FU) adjuvant chemotherapy and colorectal cancer (CRC) patients' prognosis are not well known. We performed an exploratory study to investigate the association between APC mutations and the survival of Taiwanese CRC subjects who received 5-FU adjuvant chemotherapy.
Full-length APC gene isolated from tumor tissue and adjacent normal colon tissue from 117 CRC subjects was sequenced. Various characteristics of the 117 subjects were recorded and used in the Cox proportionalhazard model analyses.
Although the subject survival rate was associated with the cancer stage, but not with the occurrence of APC mutations, we demonstrate a significant interaction between the somatic APC mutations and 5-FU adjuvant chemotherapy to the prognosis of CRC subjects. Subjects carrying APC mutation(s) and receiving 5-FU adjuvant chemotherapy demonstrate increased hazards (vs. no APC mutation or chemotherapy) for all cause (hazard ratios = 5.565; P = 0.042) or CRC deaths (hazard ratios = 6.920; P = 0.043). 5-FU adjuvant chemotherapy only decreases hazards in CRC subjects without APC mutation(s) for all cause death (hazard ratios = 0.257; P = 0.003) or CRC death (hazard ratios = 0.342; P = 0.028).
5-FU adjuvant chemotherapy only prevents CRC subjects without somatic APC mutation(s) from all cause death or CRC death. It needs further studies with larger sample size and longer follow-up time to confirm these results.
American journal of clinical oncology 04/2009; 32(2):122-6. · 2.21 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the association of methylation in the promoter regions of adenomatous polyposis coli (APC) and O(6)-methylguanine-DNA methyltransferase (MGMT) and the survival of Taiwanese colorectal cancer (CRC) subjects who received 5-fluorouracil (5-FU) adjuvant chemotherapy.
DNA isolated from tumor tissue of 117 CRC subjects was analyzed for the existence of methylation in the promoter regions of APC and MGMT by methylation-specific PCR. Various characteristics of the 117 subjects were recorded and used in the Cox proportional-hazard model analyses. Methylation in the promoter region is 62.4% (73/117) for APC and 60.7% (71/117) for MGMT in our CRC patients. Subjects presenting methylation in the APC promoter demonstrate significantly lower hazards for all causes of death (hazard ratios=0.378, p=0.011) or CRC deaths (hazard ratios=0.426, p=0.039). However, no significant correlation is found between the methylation of MGMT promoter and the prognosis of CRC subjects. In addition, no interaction between 5-FU adjuvant chemotherapy and methylation of the two genes are observed.
Methylation in the APC promoter may serve as a predictor for the prognosis of Taiwanese CRC patients.
Genetic Testing and Molecular Biomarkers 03/2009; 13(1):67-71. · 1.11 Impact Factor
