The expression and significance of chromobox protein homolog 2 in breast cancer

Objective: To study the relationship between the expression of Chromobox protein homolog (CBX) mRNA and the clinicopathological prognosis of breast cancer, and to investigate the possibility of Chromobox protein homolog 2 as a therapeutic target for breast cancer. Methods: First, we analyzed the mRNA expression of 8 CBX family genes by METABRIC database, and investigated the relationship between the expression of CBX2 mRNA and the clinicopathological parameters of breast cancer. Then we explored its relationship with prognosis. CBX2 siRNA was used to treat breast cancer cell lines with high expression of CBX2(SUM159 and SUM1315). The effects of knockdown of CBX20 on mRNA and protein expression and cell proliferation were observed. Results: According to the analysis of METABRIC database, among the 8 CBX genes, the most obvious increase in mRNA expression was CBX2, and 22.47% (445/1 980) of the patients showed high mRNA expression. The high expression of CBX2 was closely related to tumor histological grade and the molecular type of breast cancer (P<0.001). Compared with the low-expression group of CBX2 mRNA, the proportion of HER2 breast cancer (28.1% vs 7.5%) and Basal-like (44.5% vs 8.5%) in the high-expression group were both higher. Patients with high CBX2 expression had significantly shorter disease-free survival (DFS) and overall survival (OS). The knockdown of CBX2 by siRNA inhibited the proliferation of breast cancer cells. Conclusion: CBX2 is closely related to the prognosis of breast cancer and may be a target for breast cancer treatment.