Abstract
The aim of the present study was to investigate the correlation of enhancer of Zeste homolog 2 (EZH2) and SET and MYND domain containing 3 (SMYD3) gene polymorphisms with breast cancer susceptibility and prognosis. A total of 712 patients with breast cancer and 783 healthy individuals were selected. Normal breast epithelial cells MCF-10A and breast cancer cells MCF-7, MDA-MB-231, T47D, and Bcap-37 were cultured. Polymerase chain reaction (PCR)-restriction fragment length polymorphism method was applied for genotyping. Reverse-transcription quantitative PCR (RT-qPCR) and Western blotting were used to examine EZH2 and SMYD3 expression in breast cancer tissues and cells. The risk factors and prognostic factors for breast cancer were estimated. The C allele of EZH2 rs12670401 (odds ratio (OR) =1.255, 95% confidence interval (95% CI): 1.085-1.452), T allele of EZH2 rs6464926 (OR =1.240, 95% CI: 1.071-1.435), and three alleles of SMYD3 variable number of tandem repeats (VNTRs) (OR =1.305, 95% CI: 1.097-1.552) could increase susceptibility to breast cancer. Combined genotypes of EZH2 rs12670401 (TC + CC) and EZH2 rs6464926 (CT + TT) were associated with breast cancer susceptibility. Breast cancer tissues had higher EZH2 and SMYD3 expression. EZH2 rs12670401, EZH2 rs6464926, age of menarche, and menopausal status were associated with breast cancer susceptibility. Patients with TT genotype of EZH2 rs12670401 or with CC genotype of EZH2 rs6464926 had higher overall survival (OS). EZH2 rs12670401, EZH2 rs6464926, and clinical staging were independent prognostic factors for breast cancer. SMYD3 VNTR polymorphism exhibited no association with susceptibility and prognosis. EZH2 rs12670401 and rs6464926 polymorphisms, EZH2 and SMYD3 expression, clinical staging, lymph node metastasis, human epidermal growth factor receptor-2 (HER2) status, and metastasis may be correlated with breast cancer susceptibility and prognosis.