Detection of Promoter Hypermethylation of GSTP1 and CDH1 Genes and the Relationship of Histopathological Parameters of the Breast

Background: Breast cancer is the most common cancer in women. Histopathology plays an important part in determining the treatment strategy for women with breast cancer. GSTP1 plays an important role in protecting cells from cytotoxic and carcinogenic agents and it is expressed in normal tissues at variable levels in different cell types. CDH1 plays a critical role for establishment and maintenance of polarity and differentiation of epithelium during the development period. Also, it plays an important role in signal transduction, differentiation, gene expression, cellmotility and inflammations. Methods: In this study the promoter methylation levels of GSTP1 and CDH1 gene which are associated with breast cancer were investigated by technique of Methylation Sensitive High Resolution Melting Analysis (MS-HRM). We analysed primary tumor core biopsies from 80 high-risk primary breast cancer patients (tumors ≥ 2 cm and/or lymphatic metastase and/or distant metastases and/or under 40 years). Also the patients’ histopathologic types were associated with the methylation levels. Results: In our study the promoter hypermethylation status was observed at different rates;GSTP1 and CDH1 hypermethylation frequencies were 82% and 95% respectively. The promoter hypermethylation levels of the genes were found to be significant with lymph node positivity, ER positivity and HER2/neu negativity. Conclusion: Our study is important as being the first study that analyzes association between histopathologic type and GSTP1 and CDH1 gene promotor methylation status in Turkish population.

Triple Effect of Doxorubicin, 5-Fluorouracil, Propranolol on Cell Survival on MCF-7 Breast Cancer Cell Line

Purpose: Investigating the triple effect of doxorubicin, 5-fluorouracil, propranolol on MCF-7 (ER+, WTp53) breast cancer cell line with MTT test and survival analysis. Materials/Methods: In order to determine effective dosages of a combination of doxorubicin, 5-fluorouracil, propranolol on the MCF-7 cell line by using MTT and survival analysis technique. Result: IC50 values acquired by MTT tests are 0.01 mg/ml for doxorubicin, 6 mg/ml for 5-fluorouracil, 30 mg/ml for propranolol and 0.2/1/30 mg/ml (with previous respect) if all three agents are combined. It is found that the use of doxorubicin, 5-fluorouracil, and propranolol in combination is much effective than their single application. Discussion: Moderate concentrations of doxorubicin, 5-fluorouracil, and propranolol, if they are applied individually, showed high toxicity. When we used these drugs in combination;toxic effects lessened with respect to monotherapy. In the MCF-7 cell line, doxorubicin (IC50: 0.01 μM) increases cell death rates significantly and propranolol (IC50: 3 μM) has minimum effects in monotherapy in contrast to others. Propranolol is only superior to itself in combination therapy (IC50: 4 μM). However 5-fluorouracil (IC50: 30 μM) showed antagonistic effects with respect to other drugs. Additionally, having applied the three drugs in combination on the MCF-7 cell line for the first time in literature, it is highly possible to assess the application of doxorubicin, 5-fluorouracil and propranolol combination as a novel therapy option.

Investigation of Methylation Profiles of TP53, Caspase 9, Caspase 8, Caspase 3 Genes Treated with DNA Methyl Transferase Inhibitor (DNMTi) Zebularine (ZEB) and Caffeic Acid Phenethyl Ester (CAPE) on MCF-7 and MDA-MB-231 Breast Cancer Cell Lines

Purpose: MCF-7 (ER+, WTP53) and MDA-MB-231 (ER Met, Mutant P53) Caffeic Acid Phenethyl Ester (CAPE) and DNA Methyl Transferase Inhibitor (DNMTi) in breast cancer cell lines of Zebularine (ZEB) single and combined application of TP53, caspase-9, caspase 8 and caspase-3 genes as a result of the use of single and combined drug methylation profiles are aimed to be evaluated by specific PCR method. Material-Metods: In the MCF-7 and MDA-MB-231 breast cancer cell lines, MTT test and survival analysis were performed as a result of single and combined application of CAPE and Zebularine and Methylation Specific PCR was performed to examine the methylation of caspase-3, caspase-8, caspase-9 and TP53 genes. Results: According to the results of 24-hour drug administration, the IC50 for the MCF-7 cell line was determined as 200 μM, for CAPE 40 μM and for the combined values of 50 μM ZEB + 5 μM CAPE. The effects of caspase-3, caspase-8, caspase-9 and TP53 genes on the methylation level of ZEB, CAPE and ZEB + CAPE drug combination were determined by using bisulfite modified DNAs in MCF-7 and MDA-MB-231 cell lines. Discussion: In the MCF-7 cell line, the 120 μM ZEB viability rate was 51%, and the viability of 80 μM ZEB MDA-MB-231 breast cancer cells decreased by 59.7%. After 20 μM CAPE, viability in MCF-7 cells decreased by 31% in 120 μM CAPE and MDA-MB-231 cells decreased by 41%. The viability with 40 μM CAPE decreased by 19% in MDA-MB-231 cells. It was found that 20 μM CAPE concentration was associated with TP53 methylation in MCF-7 cell lines. The 80 μM ZEB concentration was found to be closely related to the unmethylated status of the TP53 gene. These results obtained with 50 μM ZEB + 5 μM CAPE application were found to be related to the methylated-unmetylated status of the TP53 gene in half (50%). For the caspase-9 gene of MDA-MB-231 cells, 80 μM ZEB concentration was found to be associated with unmetylated status. The effective use of drugs with low concentrations of the drug dose provides a more appropriate approach in terms of treatment.

Investigation of DNAmethylation of TWIST Gene in Breast Cancer and Its Relationship to Histopathological Features

BACKGROUND: Promoter hypermethylation and global hypomethylation in the human genome are hallmarks of most cancers. OBJECTIVE: The aim of this study is to assess the methylation profile patterns of TWIST gene and to investigate the relationship of methylation with pathological features. METHODS: Romoter CpGisland methylation of TWIST which can be related in breast cancer was performed by methylation-sensitive high resolution melting (MS-HRM) analysis. Formalin-fixed, paraffin-embedded (FFPE) tissue samples of 80 patients with a diagnosis of primary breast cancer from Eskisehir Osmangazi University medical faculty of Oncology Clinic were included. RESULTS: In our study, the promoter hypermethylation frequency of TWIST gene was 25.0%. With these results, when the prognostic factors of the patients were analyzed, tumor stage and age were found to be meaningless with the hypermethylation of TWIST gene, but found to be significant with lymph node positivity, ER positivity, PR negativity, and HER2/NEU negativity. CONCLUSION: Our study is important as being the first study that analyzes association between histopathologic type and TWIST gene promotor methylation status in Turkish population.

Investigation of the Effects of Zebularine on Caspase-3 and Caspase-9 Involved in Anticancer and Apoptotic Mechanisms in SKBR3 Breast Cancer Cell Line

The aim of this study is to investigate the anti-proliferative effects of Zebularine on caspase-3 and 9 genes by methylation and protein expression on SKBR3 cells. The SKBR3 cells were treated with Zebularine at different concentrations (0 - 140 μM) for 24 - 96 hours and the effects on the cell viability were shown. The effects on the cell migration and cell transformation were also demonstrated at the specified dose (IC50 = 40 μM). At the same time, the HRM method and western-blot analysis were used to understand the effects in the apoptotic mechanism. According to the obtained results, it was observed that Zebularine significantly decreased the cell proliferation, cell migration and the cell growth (p < 0.001). As a result of the methylation analyzes performed on SKBR-3 cells at the applied dose, it was observed that Zebularine caused a decrease in both caspase-3 and 9 methylation rates at the 72nd hour. However, both reductions in the methylation levels didn’t cause a significant change (p > 0.05). At the same time, it was detected by the western-blot analyses that there was a time dependent increase in caspase-3 genes while a decrease was detected in the caspase-9 gene in progress of time. The obtained results showed that the methylation changes occurring in the caspase genes weren’t related to the protein levels. According to these results, supportive results are obtained showing that the Zebularine can be used in chemotherapy and that this study is unique since it is the first study in the literature intending to investigate the effects of Zebularine on the SKBR3 cells.

The Evaluation of the Effects of Temozolomide on MGMT Gene Expression in MCF-7 and SKBR3 Human Breast Cancer Cell Lines

Background and Aim: In this study, it was aimed to examine the cytotoxic effect of temozolomide (TMZ) treatment, on MCF-7 and SKBR3 cell lines, to study the methylation levels of MGMT gene expression and gene promoter region. Methods: The MTT test was performed to determine the effective dose of TMZ. The time-dependent cell survival test was performed after the IC50 value was found. Western blotting was performed to determine MGMT gene expression levels. High Resolution Melting (HRM) technique was used to determine the methylation levels of MGMT gene promoter region. Results: TMZ has been shown to have a high cytotoxic effect on SKBR3 cell line and low cytotoxicity on MCF-7. When MGMT expression levels before and after TMZ treatment were observed by western blotting, the gene expression levels of TMZ treatment were shown to decrease in both cell lines. It was observed that MGMT gene promoter region was hypermethylated in two cell lines, and that the application of TMZ further increased the methylation levels in the promoter region. Conclusions: It was seen that TMZ could be used as a single agent in SKBR-3 cell line. With this study on breast cancer, it is expected that temozolomide treatment will lead future in vitro and in vivo studies for breast cancer.