Expression changes of BIK in breast cancer tissues of different histological subtypes

Objective: The objective of the study was to determine the expression levels of BIK in breast cancer (BC) tissues of different histological subtype and to delve into the participation of BIK in this type of cancer. Materials and methods: B/K and p-BIK (the phosphorylated form) protein expressions were tested by immunohistochemistry in BC tissue microarrays (Tumoral In = 90] and adjacent In = 40] tissues). Results: The data revealed an overexpression of B/K in invasive ductal (Grades I, IIA, and IIB) and in lobular (Grades HA and IIB) carcinomas compared to their respective adjacent tissues. By contrast, canalicular carcinoma (Grades I and 11B) and phyllodes tumors had very low expression levels of BIK. Only levels of p-BIK were shown to be increased in invasive ductal carcinoma (Grades I, IIA, and IIB). Meanwhile, quantitative polymerase chain reaction analysis showed lower B/K levels in MCF-10A and MCF-7 cells than in MDA-MB-231 and human mammary epithelial cells. In agreement with this, B/K protein was shown to be overexpressed in MDA-MB 231 relative to MCF-7 cells. Conclusions: Our results showed an association between BIK expression and the BC tumor subtype under study, which could be related to different OK functions in the BC subtypes.