Breast cancer metastatic potential correlates with a breakdown in homospecific and heterospecific gap junctional intercellular communication.

Breast cancer progresses toward increasingly malignant behavior in tumorigenic and metastatic stages. In the series of events in the metastatic stage, tumor cells leave the primary tumor in breast and travel to distant sites where they establish secondary tumors, or metastases. In this report, we demonstrate that cell-cell communication via gap junctions is restored in the metastatic human breast carcinoma cell line MDA-MB-435 when it is transfected with breast metastasis suppressor 1 (BRMS1) cDNA. Furthermore, the expression profile of connexins (Cxs), the protein subunits of gap junctions, changes. Specifically, the expression of BRMS1 in MDA-MB-435 cells increases Cx43 expression and reduces Cx32 expression, resulting in a gap junction phenotype more similar to normal breast tissue. Taken together, these results suggest that gap junctional communication and the Cx expression profile may contribute to the metastatic potential of these breast cancer cells.