PAR2 on oral cancer cells and nociceptors contributes to oral cancer pain that can be relieved by nanoparticle-encapsulated AZ3451

Oral cancer is notoriously painful. Activation of protease-activated receptor 2 (PAR2, encoded by F2RL1) by proteases in the cancer microenvironment is implicated in oral cancer pain. PAR2 is a G protein-coupled receptor (GPCR) expressed on neurons and cells in the cancer microenvironment. Sustained signaling of PAR2 from endosomes of neurons mediates sensitization and nociception. We focused on the differential contribution of PAR2 on oral cancer cells and neurons to oral cancer pain and whether encapsulation of a PAR2 inhibitor, AZ3451 in nanoparticles (NP) more effectively reverses PAR2 activation. We report that F2RL1 was overexpressed in human oral cancers and cancer cell lines. Deletion of F2RL1 on cancer cells reduced cancer-associated mechanical allodynia. A third-generation polyamidoamine dendrimer, functionalized with cholesterol was self-assembled into NPs encapsulating AZ3451. NP encapsulated AZ3451 (PAMAM-Chol-AZ NPs) more effectively reversed activation of PAR2 at the plasma membrane and early endosomes than free drug. The PAMAM-Chol-AZ NPs showed greater efficacy in reversing nociception than free drug, with respect to both level and duration, in three preclinical mouse models of oral cancer pain. The antinociceptive efficacy was confirmed with an operant orofacial assay. Genetic deletion of F2RL1 on cancer cells or F2rl1 on neurons each partially reversed mechanical cancer allodynia. The remaining nociception could be effectively reversed by PAMAM-Chol-AZ NPs. These findings suggest that PAR2 on oral cancer cells and neurons contribute to oral cancer nociception and NPs loaded with a PAR2 antagonist provide increased antinociception and improved oral function compared to free drug.