Granulocyte-Colony Stimulating Factor-Induced Neutrophil Recruitment Provides Opioid-Mediated Endogenous Anti-nociception in Female Mice With Oral Squamous Cell Carcinoma

Nicole N. Scheff, Robel G. Alemu, Richard Klares, Ian M. Wall, Stephen C. Yang, John C. Dolan, Brian L. Schmidt

Research output: Contribution to journalArticlepeer-review


Oral cancer patients report severe function-induced pain; severity is greater in females. We hypothesize that a neutrophil-mediated endogenous analgesic mechanism is responsible for sex differences in nociception secondary to oral squamous cell carcinoma (SCC). Neutrophils isolated from the cancer-induced inflammatory microenvironment contain β-endorphin protein and are identified by the Ly6G+ immune marker. We previously demonstrated that male mice with carcinogen-induced oral SCC exhibit less nociceptive behavior and a higher concentration of neutrophils in the cancer microenvironment compared to female mice with oral SCC. Oral cancer cells secrete granulocyte colony stimulating factor (G-CSF), a growth factor that recruits neutrophils from bone marrow to the cancer microenvironment. We found that recombinant G-CSF (rG-CSF, 5 μg/mouse, intraperitoneal) significantly increased circulating Ly6G+ neutrophils in the blood of male and female mice within 24 h of administration. In an oral cancer supernatant mouse model, rG-CSF treatment increased cancer-recruited Ly6G+ neutrophil infiltration and abolished orofacial nociceptive behavior evoked in response to oral cancer supernatant in both male and female mice. Local naloxone treatment restored the cancer mediator-induced nociceptive behavior. We infer that rG-CSF-induced Ly6G+ neutrophils drive an endogenous analgesic mechanism. We then evaluated the efficacy of chronic rG-CSF administration to attenuate oral cancer-induced nociception using a tongue xenograft cancer model with the HSC-3 human oral cancer cell line. Saline-treated male mice with HSC-3 tumors exhibited less oral cancer-induced nociceptive behavior and had more β-endorphin protein in the cancer microenvironment than saline-treated female mice with HSC-3 tumors. Chronic rG-CSF treatment (2.5 μg/mouse, every 72 h) increased the HSC-3 recruited Ly6G+ neutrophils, increased β-endorphin protein content in the tongue and attenuated nociceptive behavior in female mice with HSC-3 tumors. From these data, we conclude that neutrophil-mediated endogenous opioids warrant further investigation as a potential strategy for oral cancer pain treatment.

Original languageEnglish (US)
Article number217
JournalFrontiers in Molecular Neuroscience
StatePublished - Sep 16 2019


  • anti-nociception
  • cancer
  • neutrophils
  • opioids
  • pain
  • sex differences
  • squamous cell carcinoma

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience


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