Abstract 19363: Migration of MicroRNAs From Cardiomyocytes to Cancer Cells Interferes With Tumor Formation in the Adult Heart

The low incidence of cardiac tumors has been attributed to tissue pressure dictated by myocardial mechanics and large coronary blood flow. These variables, however, have failed to consider the possibility that the rare occurrence of heart neoplasms may be dictated by the molecular characteristics of cardiomyocytes. We have shown that miR-1, miR-133a, and miR-499 translocate from myocytes to co-cultured MCF7 breast cancer cells, inhibiting their growth. The transfer of miRs is mediated by gap junction channels and is abolished by Cx43 and Cx45 silencing. Although these in vitro results provided important information on the inhibitory function of miRs in cell proliferation, co-culture of myocytes and cancer cells does not mimic the in vivo organization of the myocardium that allows the formation of multiple sites of coupling between myocytes and tumor cells. To reproduce, at least in part, the in vivo condition, we developed first a physiological model of organ culture. Thick vibratome-cut myocardial slices...