Schwann cell activation in oral cancer perineurial invasion and neuropathic pain - PROJECT SUMMARY/ABSTRACT
Oral cancer patients suffer from pain with impaired oral function. Oral cancer pain is initiated and maintained in
the periphery and worsens during cancer progression. Perineural invasion (PNI), defined as cancer invading in,
around, or along the nerve, correlates with increased pain severity and poor prognosis. Treatment options for
pain are limited. No targeted treatments for PNI exist. Current research on oral cancer pain mainly focuses on
the effect of cancer mediators on primary afferent neurons. Neuropathic pain caused by PNI is rarely
addressed mechanistically. The role of Schwann cells (SCs), the most prevalent cell type supporting peripheral
nerves, has not been defined in oral cancer PNI and pain. We found that oral cancer induces SC activation, a
well-known response of SCs to nerve injury. Oral cancer cells and SCs mutually promote proliferation,
migration, and invasion. Supernatant from oral cancer-activated SCs induces nociceptive behaviors in mice.
We found that oral cancer cells are enriched with the soluble form of tumor necrosis factor (sTNF), a master
regular of cytokines. sTNF is known to activate SCs and mediates neuropathic pain. The primary receptor for
sTNF is TNFR1. We hypothesize that sTNF activates SCs through TNFR1 to promote oral cancer PNI and
neuropathic pain. Our hypothesis is based on our observations in patients, cell culture and animal models of
oral cancer and PNI. This proposal will combine expertise from oncology, pathology, electrophysiology, cell
biology, nerve ultrastructure, animal behavior, and statistics to: Aim 1. Evaluate associations between SC
activation, SC TNFR1 expression, PNI, and pain in human oral cancer. Aim 2. Characterize the effect of sTNF
neutralization or SC TNFR1 gene deletion on oral cancer pain. We will determine whether sTNF-TNFR1
mediates SC activation, which causes SCs to release nociceptive mediators, and/or is accompanied by
myelin/axon abnormalities, resulting in nociceptor hypersensitivity and neuropathic pain. Aim 3. Characterize
the effect of sTNF neutralization or SC TNFR1 gene deletion on oral cancer PNI. We will test whether sTNF-
TNFR1 mediated SC activation facilitates proliferation, migration, and invasiveness between SCs and oral
cancer cells, promoting PNI. Our objective is to elucidate the mechanism of SC activation and to test the
therapeutic potential of controlling SC activation to reduce oral cancer PNI and pain. Understanding how SCs
contribute to oral cancer PNI and neuropathic pain may reveal new opportunities and strategies to interrupt
these co-morbidities of oral cancer.