GJIC Enhances the phototoxicity of photofrin-mediated photodynamic treatment by the mechanisms related with ROS and Calcium pathways.

Despite initially positive responses, recurrences after Photodynamic treatment (PDT) can occur and there is need for improvement in the effectiveness of PDT. Our study uniquely showed that there was a significantly gap junctional intercellular communication (GJIC)-dependent PDT cytotoxicity. The presence of GJIC composed of Connexin 32 increased the PDT phototoxicity in transfected HeLa cells and in the xenograft tumors, and the enhanced phototoxicity of Photofrin-mediated PDT by GJIC was related with ROS and calcium pathways. Our study indicates the possibility that up-regulation or maintenance of gap junction functionality may be used to increase the efficacy of PDT. The phototoxicity effect of Photofrin was substantially greater in Dox-treated cells, which expressed the Cx32 and formed the GJ, than Dox-untreated.