Expressions of EZH2 and DLC1 in breast cancer tissues and cell lines and their correlation / 肿瘤

ABSTRACT

Objective: To study the expressions of enhancer of zeste homolog 2 (EZH2) and deleted in liver cancer-1 (DLC1) in breast cancer tissues and cell lines, and to explore their relationship. Methods: The expressions of EZH2 and DLC1 proteins in 120 cases of breast cancer tissues and 63 cases of para-cancerous tissues were detected by immunohistochemistry. The expression levels of EZH2 and DLC1 mRNAs and proteins in 20 cases of breast cancer tissues, 20 cases of the corresponding para-cancerous tissues, breast cancer MCF-7 and MDA-MB-231 cells and the normal mammary epithelial HBL100 cells were detected by real-time fluorescent quantitative PCR and Western blotting, respectively. The specific siRNA targeting EZH2 gene was transfected into MDA-MB-231 cells by liposome, then the expression levels of EZH2 and DLC1 mRNAs and proteins in MDA-MB-231 cells were detected again by realtime fluorescent quantitative PCR and Western blotting, respectively. Results: The positive expression rate of EZH2 in breast cancer tissues was significantly higher than that in corresponding para-cancerous tissues (P = 0.000). The positive expression rate of DLC1 in breast cancer tissues was significantly lower than that in corresponding para-cancerous tissues (P = 0.008). The expression rates of EZH2 and DLC1 were significantly correlated with tumor size and lymph node metastasis (both P < 0.05). The expression levels of EZH2 mRNA and protein in breast cancer tissues and breast cancer MCF7 and MDA-MB-231 cells were signifiicantly higher than those in corresponding para-cancerous tissues and normal breast epithelial HBL100 cells (all P < 0.01), but the expression levels of DLC1 mRNA and protein were lower than those in corresponding para-cancerous tissues and normal breast epithelial HBL100 cells (all P < 0.01). After EZH2 gene-silencing, the expression levels of DLC1 mRNA and protein in MDA-MB-231 cells were increased (both P < 0.05). Conclusion: There is a negative correlation between the expressions of EZH2 and DLC1 in breast cancer, and the inhibition of EZH2 expression can restore the expression of DLC1; which suggests that EZH2 maybe promote the occurrence and development of tumor by inhibiting the expression of DLC1.