# Protease/PAR2/TRPV4 Axis and Oral Cancer Pain

> **NIH NIH R01** · NEW YORK UNIVERSITY · 2020 · $731,251

## Abstract

Oral cancer induces severe pain that disrupts talking, eating and drinking. Patients develop tolerance to the
opioids used to treat this pain (mechanical allodynia); progressively larger doses are required. Unfortunately,
opioids produce debilitating side effects including profound sedation. A non-opioid pharmacologic strategy to
alleviate oral cancer pain is imperative; patients wait days or weeks before surgical resection, suffer from
recurrence or cannot be cured. In previous work we found that protease-activated receptor-2 (PAR2)
contributes to oral cancer mechanical allodynia. In more recent work we demonstrated that oral cancer and
associated macrophages secrete proteases into the oral cancer microenvironment. We found that two poorly
characterized proteases, legumain (Lgmn) and cathepsin-S (Cat-S), exhibit highly upregulated expression and
activity in the oral cancer microenvironment and potentially mediate cancer pain. These proteases cleave
PAR2 on sensory neurons. Cleavage at specific sites on PAR2 stabilizes receptor conformations which in turn
promote activation of receptor signaling and trafficking pathways. These signaling pathways lead to TRPV4
activation and hyperexcitability of nociceptors. The work we now propose will define mechanisms of Lgmn and
Cat-S in oral cancer pain. We propose to identify and localize activated proteases in oral cancers using our
fluorescently-quenched activity-based probes (qABPs) that covalently interact with activated proteases. We will
unequivocally identify and determine the cellular origin of activated proteases present in tumors from patients
with oral cancer. We will then analyze the correlation between protease activity and pain scores, and
determine whether tumor proteases induce PAR2-dependent activation of nociceptors. Using mice that lack
PAR2 or TRPV4 in Nav1.8 nociceptors, and our validated models of oral cancer pain, we will determine
whether tumor cell and macrophage proteases cause pain by activating PAR2 and TRPV4 on nociceptors.
Furthermore, we will use our new Par2-muGFP mice for PAR2 localization and trafficking with high specificity
and spatiotemporal fidelity. Lastly we will define the mechanisms by which tumor cell and macrophage
proteases activate PAR2 and TRPV4, induce hyperexcitability of nociceptors, and cause oral nociception. We
assert that protease inhibitors as well as PAR2 and TRPV4 antagonists hold therapeutic potential for oral
cancer pain; we ultimately seek to exploit these mechanisms to develop cancer pain therapies.

## Key facts

- **NIH application ID:** 9839371
- **Project number:** 5R01DE026806-03
- **Recipient organization:** NEW YORK UNIVERSITY
- **Principal Investigator:** NIGEL W BUNNETT
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $731,251
- **Award type:** 5
- **Project period:** 2018-01-01 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9839371

## Citation

> US National Institutes of Health, RePORTER application 9839371, Protease/PAR2/TRPV4 Axis and Oral Cancer Pain (5R01DE026806-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9839371. Licensed CC0.

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