The Study Of PTEN Gene Promoter Methylation And Triple-negative Breast Cancer

Objective:To observe the methylation level of the PTEN gene promoter in the triple-negative breast cancer(TNBC) and normal breast tissues, and to analyzed correlation between methylation levels of PTEN and clinical and pathological features of age, tumor size, lymph node metastasis, clinical stage, histological grade, etc. thus provide a theoretical basis for further research of the role and molecular mechanism of PTEN gene in the occurrence and development of TNBC.Methods:1 Select 32 cases of tissue specimens of the triple negative breast cancer patients who were in Hebei General Hospital from January, 2009 to December, 2014. and pathologically confirmed after surgery(including 25 cases of paraffin specimen of the triple negative breast cancer, and 7 cases of fresh TNBC). Patients were all females, aged from 38 to 81, with a median age of 52, all of them didn’t received chemotherapy, radiotherapy and other cancer-related treatment. Specimens of the triple negative breast cancer included 24 cases of invasive ductal carcinoma, 2 cases of medullary carcinoma, 2 cases of metaplastic cancer, 1 case of cribriform cancer, 2 cases of ductal carcinoma in situ and 1 case of small tube cancer. Clinical staging the NCCN guidelines of the breast cancer, in china,2014. Include 2 cases of clinical stage 0, 8 cases of clinical stageⅠ, 16 cases of stageⅡ, 8 cases of the stage Ⅲ. Select another total 11 cases of fresh normal breast tissues as the control group. All here 32 patients with TNBC were followed up 6 months to 74 months.2 Pyrosequencing method was used to test methylation levels of the PTEN gene promoter in the TNBC tissues and normal breast tissues, and relationship was analysised between methylation levels of the PTEN promoter region and clinical and pathological features of age, tumor size, clinical stage, lymph node metastasis, histological grading, Ki-67, VEGF, P53, EGFR, E-cadherin expression and so on.3 Statistical analysis: The average methylation rate of TNBC tissues and the PTEN gene promoter region of the normal tissues were analysised. TNBC tissues were classified and compared based on clinical and pathological indicators separately. Measurement data results were expressed by(mean±standard deviation), and the results analysis use the test. Use the SPSS21.0 software to conduct data analysis, P<0.05 was considered statistically significant.Results:1 The pyrosequencing assay was used to test the PTEN gene promoter methylation status in 32 cases of TNBC and 11 cases of normal tissues, the results showed that the PTEN promoter methylation rate in TNBC is 20.74±7.66, and which in the normal breast tissue is 6.27±4.42, the difference was statistically significant(P<0.05).2 The PTEN gene promoter methylation rates in TNBC were analysied with clinical characteristics of the patients, the results showed that methylation degree of the PTEN promoter region has no significant correlation with age, tumor size, histological grade,(P>0.05), but has statistically different correlation with the clinical staging and lymph node metastasis(P<0.01).3 The PTEN gene promoter methylation rates in TNBC tissues were analyzed with the pathological features of patients, and the results showed that the methylation degree of the PTEN promoter region has statistically different relationship with Ki-67, VEGF, P53, EGFR(P<0.05), and has no relationship with the E-cadherin expression(P>0.05).Conclusions:1 The methylation degree of the PTEN gene promoter region of TNBC patients is higher than normal breast tissues, which suggest that methylation of the PTEN gene promoter region plays an important role in occurrence and development of TNBC.2 The methylation degree of the PTEN gene promoter region has relevance with TNBC patients’ lymph node metastasis, clinical staging, expression of Ki-67, VEGF, P53, EGFR; Moreover, there is no significantly relevance with patients’ age, tumor size, histological grading, which suggest that the methylation degree of the PTEN gene promoter region could be one of the objective indicators to judge the pathobiology behavior of the triple negative breast cancer.