ABSTRACT
A new class of glutathione S-transferase enzymes, named omega, (GSTO) has recently been identified and shown to be expressed in various human tissues. Though GSTO1 and GSTO2 polymorphisms have been reported and found to be associated with the risk of certain cancers, their correlation with cancer-patient outcomes has been demonstrated in a very small number of studies. The aim of this study was to evaluate the potential relationship between GSTO2 polymorphism and clinical outcome parameters and the disease-free survival of breast-cancer patients. DNA was extracted from the formalin-fixed, paraffin-embedded breast-cancer tissues of 83 patients; gene polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). No significant association was found between GSTO2 polymorphism and clinical outcome parameters or five-year disease-free patient survival. It was concluded that GSTO2 polymorphism does not influence the clinical outcome or survival of breast cancer patients. (Thai Cancer J 30;4:153-159)
ABSTRACT
HER-2/neu status is used as a marker for Herceptin\® therapy. The aim of this study was to evaluate the usefulness of quantitative real-time PCR (qPCR) in determining the HER-2/neu amplification status of breast cancer, by comparing qPCR, CISH, and chromogenic in-situ hybridization (CISH) and immunohistochemistry (IHC) results from the same samples. Thirty breast carcinomas were examined using the three methods. Twenty-two tumors were 2+ or 3+ positive with IHC, while eight samples were either completely negative or 1+. Fifteen positive and twelve negative cases were detected by both CISH and qPCR, which led to similar results. Comparison of CISH and qPCR together with IHC showed that qPCR was more sensitive in detecting HER-2/neu gene amplification in tumors scored as 2+ with IHC. In conclusion, qPCR may serve as useful alternative to CISH for detecting HER-2/neu gene amplification in breast-cancer patients. (Thai Cancer J 2010;30:104-111)
ABSTRACT
A genetic polymorphism of GSTO2 causes variations in enzyme activity. It was reported that the GSTO2 wild-type (N142) allozyme showed higher levels of expression than the GSTO2 variant (D142) allozyme. Overexpression of GSTO protein has been found in chemo- and radio-resistant cancer cells. In addition, increased GSTO expression in colorectal cancer cells correlated with increased cell invasion and metastasis. Therefore, we investigated the association of GSTO2 polymorphism and prognoses for colorectal-cancer patients. Formalin-fixed, paraffin-embedded cancerous colorectal tissues from 89 patients were used to extract DNA. Gene polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results showed that wild-type GSTO2 (N142/N142) was found mainly in patients aged \> 50 years (P=0.014). No significant difference was found between GSTO2 genotype and sex, tumor stage, tumor differentiation, and EGFR. Patients carrying wild-type GSTO2 (N142/N142) had poorer survival rates than those carrying variant GSTO2 (N142/D142+D142/D142) (P=0.015). This finding suggests that a finding of wild-type GSTO2 was related to a poor prognosis. Therefore, GSTO2 polymorphism may be used as a prognostic indicator for appropriate treatment decisions in patients with colorectal cancer. (Thai Cancer J 2010;30:18-23)
ABSTRACT
The purpose of this study is to investigate aberrant methylation of p16INK4a in hepatocellular carcinoma (HCC). We determined the methylation status of CpG island of p16INK4a in 29 HCC and corresponding normal liver tissues by methylation specific-PCR method. Aberrant methylation status was detected in 41.4% of tumors and 6.9% of corresponding normal liver tissues. No significant correlations between methylation status and clinico-pathological data were found. In addition, survival analysis by multivariate Cox regression analysis showed that aberrant methylation status of p16INK4a was not an independent prognostic factor for poor survival among HCC patients. Our findings demonstrated that methylation of p16INK4a were detectable in HCC tissues of Thai patients and suggested that hypermethylation of p16INK4a may contribute to the hepatocellular carcinogenesis.
ABSTRACT
Since reports on GSTO2 polymorphism are still limited, therefore, this study was conducted to investigate an association of genetic polymorphism of GSTO2 and survival for colorectal cancer. Formalin-fixed, paraffin-embedded colorectal cancerous tissues from 26 patients who were continuously followed-up, were used to extract DNA and the gene polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism. Our findings revealed that the patients carried wild-type GSTO2 gene (N142/N142) had poorer survival rate, when compared with those carried variant GSTO2 gene (adjusted hazard ration, 14.02, P=0.08). No association of GSTO2 genotypes with overall survival was noted (P=0.142). However, this study is only a preliminary report of which the number of cases is small. Further study in a larger population is required to achieve high statistical power and consequently clarify this finding.
ABSTRACT
To our knowledge, only two reports concerning association between GSTO1 polymorphism and breast cancer risk have been revealed, but no association between GSTO1 polymorphism and clinicopathological features of patients with breast cancer have previously been reported. Therefore, in this study, the association of GSTO1 genotypes with a number of clinical parameter was investigated in 101 patients with breast cancer diagnosed and treated at the National Cancer Institute. DNA extracted from buffy coats of the cases was used to determine the genotypes by polymerase chain reaction-restriction-fragment length polymorphism. Our findings revealed that wild-type GSTO1 gene (A140/A140) significantly correlated with advanced-stage breast cancer (P=0.008). Form the literature, GSTO1 appears to be involved in drug and xenobiotic metabolism, it would be of great interest to investigate further whether resistance to radiation or chemotherapy occurs in carriers of wild-type GSTO1 gene, particularly those with advanced-stage breast cancer. Elucidating this relationship should lead to the improved clinical management of these patients.