Frequency and Association Of GSTM1 and GSTT1 Gene Polymorphisms with Survival in Breast Cancer Patients.

OBJECTIVE: Glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) are the key detoxification enzymes of xenobiotics, including chemotherapeutic drugs. The deletion polymorphisms of GSTM1 and GSTT1 genes are associated with reduced enzyme activity that influenced clinical outcomes of chemotherapeutic agents in breast cancer. However, there is limited information among Thai patients. This research aims to explore the frequency and role of GSTM1 and GSTT1 polymorphisms on survival among Thai patients with breast cancer. METHODS: The retrospective cohort study was performed. Demographic data and clinicopathology characteristics were collected from hospital base registry data and medical records. A multiplex qualitative real-time PCR method was used to detect the presence or absence of the GSTM1 and GSTT1 gene in the genomic DNA samples of the participants. RESULTS: The frequencies of the GSTM1 and GSTT1 null genotypes in 198 breast cancer patients were 65.70% and 33.30%, respectively. The overall survival at 1, 3 and 5 years were 95.00%, 83.00%, 71.00% respectively. The log rank test and Cox proportional hazards revealed a significant different in the 5-years overall survival according to lymph node metastasis and tumor stage (P = 0.014 and P < 0.001). No associations between overall survival and GSTM1 or GSTT1 genotype were found in single or combined genotypes analyses (P = 0.76 and P= 0.15). CONCLUSION: The results of our study provided the epidemiological information for prognostic of survival in breast cancer patients treated with chemotherapy.
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Negative Impact of 25-hydroxyvitamin D Deficiency on Breast Cancer Survival.

BACKGROUND: Low 25-hydroxyvitamin D [25(OH)D] levels in serum are associated with breast cancer risk. This study was conducted to determine the impact of 25(OH)D deficiency on survival of breast cancer patients. METHODS: In a retrospective cohort study of 303 patients diagnosed with breast cancer during 2011-2012 at the National Cancer Institute Thailand, all cases were followed up for 7 years. The 25(OH)D was measured by high-performance liquid chromatography (HPLC). Clinical and pathological data were collected. The Chi-square test, Kaplan-Meier and Cox regression model were used to assess the association between 25(OH)D levels and risk of death. RESULTS: Of the 303 cases aged between 24 and 78 years 51 (16.8%) died during follow-up from any cause. The mean 25(OH)D levels was 25.1±7.54 ng/ml (8.2 - 61.0 ng/ml). Thirty-three patients (10.9%) were stratified as inadequate or deficient group (<16 ng/ml) with mean survival time of 60.65 months compared to 76.24 months in insufficient or sufficient group (≥16 ng/ ml). Multivariate analysis adjusted for age, body mass index, stage, lymph node metastases, and immunohistochemical (IHC) findings (ER, PgR, HER-2, Ki-67 and P53) showed that patients with low 25(OH)D levels (<16 ng/ml) at diagnosis had a significantly higher risk of death (hazard ratio = 2.5-2.9) than the group with high 25(OH)D levels (≥16 ng/ ml). CONCLUSION: A concentration of 25(OH)D below 16 ng/ml was found to be independently associated with poor survival in breast cancer patients, regardless of age, lymph node status, stage or breast cancer subtype. An investigation of potential benefit of 25(OH)D supplements appears warranted.

Her-2/neu amplification determined by real-time quantitative PCR and its association with clinical outcome of breast cancer in Thailand.

HER-2/neu has been found to be amplified or overexpressed in about 20-30% of breast cancers, in association with negative prognosticators and shortened survival. Determination of HER-2/neu status in breast-cancer patients, to select for adjuvant treatment with trastuzumab, is becoming standard breast-cancer clinical practice. This study aimed to investigate HER-2/neu status in breast-cancer by real-time quantitative polymerase chain reaction (PCR), allowing accurate and precise quantification of HER-2/neu amplification in tumor tissues. We evaluated 112 breast-cancer samples, of which 42 (37.5%) had HER-2/neu amplification. After a mean follow-up period of 71 months, HER-2/neu amplification was found to be significantly associated with increased risk of death (HR = 6.367, 95% CI = 1.787-22.684), even after adjusting for age, clinical stage, tumor size, lymph-node status, and histologic grade. These findings support a negative prognostic role for HER-2/neu in breast-cancer survival. We suggest that real-time quantitative PCR analysis of HER-2/neu amplification represents an alternative technique for establishing HER-2/neu status in routine clinical practice.

Promoter methylation and genetic polymorphism of glutathione S-transferase P1 gene (GSTP1) in Thai breast- cancer patients.

The GSTP1 gene encodes for a detoxification enzyme involved in protecting cells from carcinogens. In breast cancer, GSTP1 polymorphisms may produce lower effective enzyme detoxification properties and GSTP1 promoter hypermethylation may result in inactivation of GSTP1 expression. We therefore hypothesized an influence on progression of breast cancer. To study the effect of GSTP1 polymorphisms and CpG-island hypermethylation on GSTP1 promoter, PCR-RFLP and methylation-specific PCR techniques were used with 41 Thai breast-cancer patients. Associations between the codon 105 (A to G) genetic polymorphism, CpG-island hypermethylation, and clinico-pathological parameters were analyzed. GSTP1 hypermethylation was found in 26% of cases and the GSTP1 polymorphism in 14%. GSTP1 hypermethylation was significantly associated with breast cancer; lymph-node metastasis (P = 0.02) while GSTP1 polymorphism status significantly varied with progesterone receptor positivity (P = 0.04). No association was found between the GSTP1 polymorphism and methylation status. The results indicated that CpG-island hypermethylation of the GSTP1 promoter is associated with a biologically aggressive phenotype, but may not be related to the codon 105 (A to G) gene polymorphism in breast-cancer patients.

Glutathione s-transferase polymorphisms in breast cancers of Thai patients.

Breast cancer is the most common cancer among women worldwide and second in Thailand. Glutathione S-transferase (GST) enzymes involved in the detoxification of reactive metabolites of carcinogens may be important in modulating susceptibility to cancers. This study aimed to determine the influence of genetic polymorphisms of glutathione S-transferase T1, M1, P1 and A1 on breast cancer in Thai patients. Links with clinico-pathological characteristics were also analyzed. The results showed no association between GSTs polymorphism and overall susceptibility to breast cancer in Thai patients (P < 0.05). However, the data pointed to a relation of the GSTP1(Ile105Val) polymorphism with progesterone receptor status (P = 0.04) and age at diagnosis (P = 0.03) of breast cancer cases. In summary, this is the first study to report associations between glutathione S-transferase T1, M1, P1 and A1 gene polymorphisms and breast cancer in Thai patients. While GST genotypes may not be associated with susceptibility, a GSTP1 polymorphism (Ile105Val) may be related to progression of breast cancer.

Role of glutathione S-transferase omega gene polymorphisms in breast-cancer risk.

BACKGROUND/AIMS: Genetically influenced variations in the levels of activity and/or expression of some members of the glutathione S-transferase (GST) family have been identified as risk factors for cancer. One, GST omega (GSTO), has been found in a very limited number of studies. The aim of the present study was to investigate the influence of GSTO1 and GSTO2 polymorphisms on breast cancer risk. METHODS: DNA isolated from the blood of 101 patients with breast cancer and 151 healthy controls was investigated for GSTO1 and GSTO2 polymorphisms by polymerase chain reaction-restriction-fragment length polymorphism. RESULTS: Univariate and multivariate analyses showed no association between GSTO1 and GSTO2 genotypes and the risk of breast cancer. A higher prevalence of wild-type GSTO1 (A140/A140) was significantly correlated with advanced-stage breast cancer (OR = 0.1, 95% CI, 0.01-0.77), but the presence of the genotype did not correlate with patient age at diagnosis, menopausal status, tumor size, lymph node metastasis, or estrogen-receptor status. No association was found between GSTO2 genotype and clinicopathological features. CONCLUSIONS: The results of the study suggest that GSTO1 and GSTO2 variants are not associated with breast cancer risk, but that wild-type GSTO1 (A140/A140) is likely among cases at an advanced stage.

Real-time quantitative PCR analysis of amplified DNA on chromosomes 4p15.2 and 6q23-24 from formalin-fixed, paraffin-embedded breast cancer tissues.

This study was performed to detect amplification of DNA sequences on chromosomes 4p15.2 and 6q23-24, obtained from formalin-fixed, paraffin-embedded, breast-cancer tissues. The prognostic relevance of the amplification was also demonstrated. DNA from formalin-fixed, paraffin-embedded tumor and corresponding normal tissues of 53 patients with breast cancer was extracted and amplified by real-time quantitative PCR technique. Amplification of the DNA sequences on chromosomes 4p15.2 and 6q23-24 was detected in 23 (43%) and 32 (60%) cases, respectively. Thirty-six (68%) cases showed amplification on both or one of the chromosomes. These frequencies are similar to that obtained from fresh samples in our previous study. In addition, amplification of the DNA on chromosomes 4p15.2 and / or 6q23-24 was predominantly observed in tumors with invasive ductal carcinoma. The findings in this study demonstrate that DNA extracted from formalin-fixed, paraffin-embedded breast tumors can be used to determine amplification of DNA sequences on selective chromosomal regions. We also suggest that the amplified DNA on chromosomal regions 4p15.2 and 6q23-24 might be involved in the development and progression of breast cancer.