Junction opener protein increases nanoparticle accumulation in solid tumors.

Carcinomas contain tight junctions that can limit the penetration and therefore therapeutic efficacy of anticancer agents, especially those delivered by nano-carrier systems. The junction opener (JO) protein is a virus-derived protein that can transiently open intercellular junctions in epithelial tumors by cleaving the junction protein desmoglein-2 (DSG2). Co-administration of JO was previously shown to significantly increase the efficacy of various monoclonal antibodies and chemotherapy drugs in murine tumor models by allowing for increased intratumoral penetration of the drugs. To investigate the size-dependent effect of JO on nanocarriers, we used PEGylated gold nanoparticles (AuNPs) of two different sizes as model drugs and investigated their biodistribution following JO protein treatment. By inductively coupled plasma mass spectrometry (ICP-MS), JO was found to significantly increase bulk tumor accumulation of AuNPs of 35nm but not 120nm particles in both medium (200-300mm3) and large (500-600mm3) tumors. Image analysis of tumor sections corroborates this JO-mediated increase in tumor accumulation of AuNPs. Quantitative intratumoral distribution analyses show that most nanoparticles were found within 100μm of the vasculature, and that the penetration profiles of AuNPs are not significantly affected by JO treatment at the 6h timepoint.