Substance P Activates Cancer Promoting Pathways in Head and Neck Cancers

Abstract

Head and neck cancer (HNC) is comprised of a multitude of malignancies that take place in the oral cavity. Neuropeptides such as Substance P (SP) are important in causing inflammation, proliferation and migration in different types of cell lines, but the precise effects and mechanisms are not yet elucidated in HNCs. Neuropeptide Substance P, along with its primary receptor, neurokinin-1 receptor (NK-1R), strongly affect the tumor microenvironment. In this study, the effects of SP, at a concentration of 100nM, was observed on HNCs including FaDu, Detroit 562 and SCC-9 cell lines. The inhibition of SP’s most influential receptor NK-1R was then blocked using the drug L-703606 at a concentration of 1M, and the resulting effects were measured. By utilizing an XTT Proliferation Assay, SP was found to significantly increase cell proliferation in all HNC cell lines tested, at the starting concentration of 100nM and throughout the increase to 10uM. SP also notably upregulated the expression of various cytokines, cytokine receptors, chemokines, chemokine receptors, MMP genes and EMT inducing genes, while the NK-1R inhibitor significantly decreased these genes, which was evaluated via RT-PCR. Furthermore, SP induced the migration rate of HNC cell lines at a concentration of 100nM and was selectively inhibited by the NK-1R receptor at a concentration of 1uM, which was evaluated via migration assay and scratch wound assay. The nuclear translocation of NF-κB was also significantly increased in response to SP in immunofluorescence studies, and decreased when treated with NK-1R inhibitor. The effects of SP at 100nM significantly increased cellular inflammation, proliferation and migration of various HNCs, and its effects were inhibited by the drug L-703606, by blocking the NK-1R receptor.