Abstract: Objective To observe the expression of CTCF in breast cancer cell lines, tumor tissue and serum of breast cancer patients, and explore preliminarily the effect of CTCF on proliferation of MCF7. Methods Western blot was used to detect CTCF expression in human breast cancer cell lines MCF7, SKBR3, MDA-MB-231 and normal breast cells MCF-10A. Real-time quantitative PCR and immunohistochemistry were applied to detect the mRNA and protein levels of CTCF in invasive ductal carcinoma (n=23), peritumoral tissue (n = 10) and fibroadenoma (n = 10). Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentration of CTCF protein in serum. Furthermore, retroviral vector containing CTCF full length was constructed and retroviruses were packaged, then MCF7 cells were infected to screen clones stably expressing CTCF. Last, MTT assay was applied to detect cell proliferation. Results CTCF expression in MCF-10A was the highest, and decreased gradually in MCF7, SKBR3 and MDA-MB-231. CTCF expression in breast carcinoma tissue were significantly lower than that in peritumoral tissue and benign lesions (P <0.01). CTCF protein concentration in serum of breast cancer patients were also significantly lower than that of healthy control (P <0.01). In addition, CTCF overexpression could inhibit the proliferation of MCF7 cells. Conclusions CTCF expression were declined significantly in breast cancer cell lines, carcinoma tissues and serum of breast cancer patients, compared with the controls. CTCF could inhibit the proliferation of breast cancer cells.

Key words: CTCF, breast cancer, proliferation