Oral cancer induced TRPV1 sensitization is mediated by PAR2 signaling in primary afferent neurons innervating the cancer microenvironment

Oral cancer patients report sensitivity to spicy foods and liquids. The mechanism responsible for chemosensitivity induced by oral cancer is not known. We simulate oral cancer-induced chemosensitivity in a xenograft oral cancer mouse model using two-bottle choice drinking and conditioned place aversion assays. An anatomic basis of chemosensitivity is shown in increased expression of TRPV1 in anatomically relevant trigeminal ganglion (TG) neurons in both the xenograft and a carcinogen (4-nitroquinoline 1-oxide)-induced oral cancer mouse models. The percent of retrograde labeled TG neurons that respond to TRPV1 agonist, capsaicin, is increased along with the magnitude of response as measured by calcium influx, in neurons from the cancer models. To address the possible mechanism of TRPV1 sensitivity in tongue afferents, we study the role of PAR(2), which can sensitize the TRPV1 channel. We show co-expression of TRPV1 and PAR(2) on tongue afferents and using a conditioned place aversion assay, demonstrate that PAR(2) mediates oral cancer-induced, TRPV1-evoked sensitivity in an oral cancer mouse model. The findings provide insight into oral cancer-mediated chemosensitivity.

Automated summary

Oral cancer patients experience sensitivity to spicy foods and liquids, but the mechanism behind this sensitivity is not yet understood. In a mouse model of oral cancer, researchers found increased expression of TRPV1 in trigeminal ganglion neurons, indicating an anatomical basis for chemosensitivity. They also discovered that PAR(2) plays a role in mediating the sensitivity induced by TRPV1 in tongue afferents in the oral cancer mouse model.