Bax Expression in Untreated Breast Cancer: An Immunocytometric Study of 255 Cases

Abstract

Background: Bax is one of the main effectors of apoptosis in breast cancer. However, in contrast with the antiapoptotic protein Bcl-2, which has been extensively studied in this tumor, there are relatively few clinical studies on the biological role of Bax in breast cancer. Materials and Methods: The expression of the apoptosis-related Bax gene was studied in a series of 255 previously untreated breast cancers by means of immuno-flow cytometry. Additionally, and by the same method, the expression of the Bcl-2, VEGF and Nup88 genes were also studied. As variables of the study for the final statistical analysis, the histological variety of the tumors, histological and nuclear grade, the expression of hormone receptors, p53, Ki-67 or c-erb-B2, axillary node invasion, tumor size and DNA-ploidy were also included. Results: The expression of the proapoptotic Bax protein was significantly associated with the expression of Nup88 (p<0.0001), VEGF (p=0.0014) and Bcl-2 (p=0.0063), all measured by the same method. An inverse correlation with c-erb-B2 expression, which almost attained statistical significance (p=0.058) was also registered. Conclusion: This study adds evidence to the little explored link between apoptosis and angiogenesis. Furthermore, it discloses a previously unreported relationship between Bax and Nup88 expression.