Implication of Connexin 43 as a Tumor Suppressor in Pathogenesis of Breast Cancer

Breast cancer (BC) is a global public health burden, constituting the highest cancer incidence in women worldwide. Connexins 43 proteins propagate intercellular communication, gap junction intercellular communication (GJIC), remarkably expressed in several tumor types including liver, prostate, and breast. This domain of Cx43 possesses functionally critical sites identical to those involved in gating of channel and phosphorylation sites for various kinases. However, the mechanism by which Cx43 down regulation occurs in breast cancer is far from clear. Several mechanisms like Cx43 promoter hyper-methylation or a cancer-specific reduction of Cx43 expression/trafficking by the modulation of various components of the Cx43 life cycle give the idea to be involved in the down regulation of Connexins in mammary glands, but irreversible mutational alterations have not yet been proved to be among them. Summarily, the efficacy or specificity of these drugs can be increased by a combinatory approach considering an effect on both the Connexins and their regulatory molecules. This chapter will summarize the knowledge about the connexins and gap junction activities in breast cancer highlighting the differential expression and functional dynamics of connexins in the pathogenesis of the disease.