RESUMO
OBJECTIVE@#To study the expression of G9a in human breast cancer, its association with the clinicopathological characteristics of breast cancer, and its effect on the proliferation of breast cancer cells.@*METHODS@#A total of 122 specimens of breast cancer tissues and 61 adjacent normal tissues resected between October, 2016 and October, 2017 were obtained from the Tissue Bank of Ningxia Medical University General Hospital. Immunohistochemistry and real-time PCR were used to detect the expression of G9a in the breast cancer tissues. The relationship of G9a with the clinicopathological features of the patients, molecular subtypes of breast cancer and the immunohistochemical markers was analyzed. A bioinformatics approach was used to analyze the expression of G9a in breast tissues and its association with the prognosis of the patients with breast cancer. UNC0631, a G9a inhibitor, was used to investigate the effect of G9a on the proliferation of breast cancer cells .@*RESULTS@#The results of immunohistochemical study, real-time PCR and bioinformatics analysis showed that G9a was highly expressed in human breast cancer tissues. G9a was highly expressed in breast invasive ductal carcinoma, and its expression was negatively correlated with age ( < 0.05). Her-2-overexpressing breast cancer showed high expressions of G9a, which was positively correlated with the expressions of Her-2, Ki-67 and E-cadherin ( < 0.05). Bioinformatics analysis suggested that a high G9a expression was an independent risk factor for poor prognosis of breast cancer. In cultured breast cancer cells, the application of the G9a inhibitor significantly inhibited the cell proliferation.@*CONCLUSIONS@#G9a is highly expressed in breast cancer tissues to promote the development and progression of breast cancer. A high G9a expression is an independent risk factor for poor prognosis of breast cancer, and G9a may serve as a new target for early diagnosis and treatment of breast cancer.
