Fibronectin Modulation of Oral Cancer Nociception - PROJECT SUMMARY Oral cancer patients suffer severe pain which intensifies in metastatic disease. Opioid-based pain manage- ment is inadequate, and marred by the onset of drug tolerance and addiction. There is an unmet clinical need for effective non-opioid analgesics to treat oral cancer pain. Oral cancer derived pain mediators activate and sensitize transient receptor potential vanilloid 1 (TRPV1) channels on trigeminal nociceptors (pain sensing neu- rons). The TRPV1 channel has emerged as a key regulator of oral cancer pain. Transcriptional profiling re- vealed 40 “pain and metastasis genes” overexpressed in metastatic cancers from patients reporting high pain compared to non-metastatic cancers. Fibronectin (protein FN1) is the most highly overexpressed pain and me- tastasis gene in oral cancer. An alternatively spliced variant of FN1 containing the “extra” type III module, EDA (Fn EDA) is only expressed in pathological conditions such as diabetes and cancer. Fn EDA is overexpressed in oral cancer and promotes tumor cell migration and invasion. There is a gap in our knowledge regarding the role of FN1 and Fn EDA as pain mediators. While studying a potential role for FN1/Fn EDA in oral cancer pain we identified that Fn EDA increased the excitability of trigeminal ganglion neurons, supporting the hypothesis that Fn EDA mediates oral cancer pain via sensitization of TRPV1+ trigeminal nociceptors. The long term goal is to identify key targets in the oral cancer microenvironment which can be utilized to alleviate oral cancer pain independent of the opioid pathway, thereby improving quality of life for patients with oral cancer. The overall objectives for this application are to (i) elucidate the clinical FN1 and Fn EDA profile in metastasis-associated pain, (ii) evaluate Fn EDA function within the nociceptive cascade, and (iii) investigate TRPV1 sensitization by Fn EDA. The central hypothesis is the identified pain and metastasis genes FN1 and Fn EDA are pain media- tors, which was formulated from study of oral cancer patients and samples, cell lines and orthotopic cancer- pain mouse models. The rationale for this project is identification of specific mechanisms of receptor activation on nociceptors in the oral cancer microenvironment will provide the foundation to develop non-opioid analge- sics to treat oral cancer pain. Three aims are proposed to test the hypothesis. Aim 1 will evaluate FN1 and Fn EDA expression in oral cancers, and analyze correlation with metastasis-associated pain using patient tissues, clinical pain scores, and multiplex immunohistochemistry. Aim 2 will evaluate Fn EDA as a nociceptive media- tor by manipulation of Fn EDA (overexpression/inhibition), and evaluate effects on nociception using mouse models of oral cancer pain. Aim 3 will evaluate the Fn EDA-TRPV1 pain axis using electrophysiology and cal- cium signaling. The proposed research is innovative as it initiates a new line of research evaluating Fn EDA as an oral cancer pain mediator. The proposed study is significant, because mitigation of oral cancer pain via Fn EDA blockade will establish a paradigm for Fn EDA inhibition in pain management strategies for other cancers that may diminish or eliminate reliance on substance use disorder-prone opioids.
