A Novel Syngeneic Immunocompetent Mouse Model of Head and Neck Cancer Pain Independent of Interleukin-1 Signaling.

BACKGROUND: Pain is one of the first presenting symptoms in patients with head and neck cancer, who often develop chronic and debilitating pain as the disease progresses. Pain is also an important prognostic marker for survival. Unfortunately, patients rarely receive effective pain treatment due to our limited knowledge of the mechanisms underlying head and neck cancer pain (HNCP). Pain is often associated with neuroinflammation and particularly interleukin (IL)-1 signaling. The purpose of this study is to develop a novel syngeneic model of HNCP in immunocompetent mice to examine the contribution of IL-1 signaling. METHODS: Male C57BL/6 mice were injected with a murine model of human papillomavirus (HPV+)-induced oropharyngeal squamous cell carcinoma in their right hindlimb to induce tumor growth. Pain sensitivity was measured via von Frey filaments. Spontaneous pain was assessed via the facial grimace scale. IL-1ß was measured by quantifying gene expression via quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA). RESULTS: Pain hypersensitivity and spontaneous pain develop quickly after the implantation of tumor cells, a time when tumor volume is still insignificant. Spinal and circulating IL-1ß levels are significantly elevated in tumor-bearing mice. Blocking IL-1 signaling either by intrathecal administration of interleukin-1 receptor antagonist (IL-1ra) or by genetic deletion (interleukin-1 receptor knockout [Il1r1-/-]) does not alleviate HNCP. CONCLUSIONS: We established the first syngeneic model of HNCP in immunocompetent mice. Unlike inflammatory or nerve-injured pain, HNCP is independent of IL-1 signaling. These findings challenge the common belief that pain results from tissue compression or IL-1 signaling in patients with head and neck cancer.

HPV+ head and neck cancer-derived small extracellular vesicles communicate with TRPV1+ neurons to mediate cancer pain.

ABSTRACT: Severe pain is often experienced by patients with head and neck cancer and is associated with a poor prognosis. Despite its frequency and severity, current treatments fail to adequately control cancer-associated pain because of our lack of mechanistic understanding. Although recent works have shed some light of the biology underlying pain in HPV-negative oral cancers, the mechanisms mediating pain in HPV+ cancers remain unknown. Cancer-derived small extracellular vesicles (cancer-sEVs) are well positioned to function as mediators of communication between cancer cells and neurons. Inhibition of cancer-sEV release attenuated pain in tumor-bearing mice. Injection of purified cancer-sEVs is sufficient to induce pain hypersensitivity in naive mice that is prevented by QX-314 treatment and in Trpv1-/- mice. Cancer-sEVs triggered calcium influx in nociceptors, and inhibition or ablation of nociceptors protects against cancer pain. Interrogation of published sequencing data of human sensory neurons exposed to human cancer-sEVs suggested a stimulation of protein translation in neurons. Induction of translation by cancer-sEVs was validated in our mouse model, and its inhibition alleviated cancer pain in mice. In summary, our work reveals that HPV+ head and neck squamous cell carcinoma-derived sEVs alter TRPV1+ neurons by promoting nascent translation to mediate cancer pain and identified several promising therapeutic targets to interfere with this pathway.