RESUMO
To explore the effect of tamoxifen on expression of ER, PR, Cerb-B2, and ki-67 in C3H mice spontaneous breast cancer model and further explore its relation with chemotherapeutic effect. Forty male C3H mice with spontaneous breast cancer aged 10 months were selected, and randomly divided into model group and tamoxifen group, with 20 mice in either group. Model group received intraperitoneal injection of normal saline, tamoxifen group received 5 mg/Kg tamoxifen injection. Tumor volume was measured every 3 days for 12 days in total. After that the mice were killed to weigh the tumor for tumor growth inhibition rate calculation; breast cancer specimen was collected, and immunohistochemistry was used to detect ER, PR, Cerb-B2, and ki-67 positive cells, western blot was used to detect expression of ER, PR, Cerb-B2, and ki-67 in breast cancer. The tumor growth inhibition rate of tamoxifen on mice was 61.56 %. Compared with model group, tumor weight in mice from tamoxifen group was significantly lower, tumor growth rate in tamoxifen group was significantly lower than model group; immunohistochemical staining results showed that compared with model group, ER, PR, Cerb-B2, and ki-67 positive cells in tumor of tamoxifen group were significantly lower (P < 0.05). Among them, ki-67 expression in tamoxifen group was negative; western blot semi-quantitative results were in accordance with immunohistochemistry results. Tamoxifen is effective on C3H mice spontaneous breast cancer. After being treated with tamoxifen, expression levels of ER, PR, Cerb-B2 and ki-67 are changed, and change of ER, PR, Cerb-B2, and ki-67 can predict the therapeutical effect of tamoxifen.