The overexpression of Bcl-2 antagonizes the proapoptotic function of the kappa-opioid receptor.

Opioid receptors are G-protein-coupled cell-surface receptors that are mainly expressed in neuronal cells. Stimulation of the kappa-opioid receptor expressed by cultured human epithelial cancer cells promotes staurosporine-induced apoptosis. In this study, while Bcl-2 did not inhibit staurosporine-induced apoptosis, it did inhibit the kappa-opioid receptor-mediated potentiation of apoptosis. The results suggest that Bcl-2 targets a step that is specific to the signaling pathway of the kappa-opioid receptor.