Effects of Vitamin D on tumor cell proliferation and migration, tumor initiation and anti-tumor immune response in head and neck squamous cell carcinomas

Abstract

Head and neck squamous cell carcinomas (HNSCCs) are among the six most common cancers, with a constantly poor prognosis. Vitamin D has been found to have antineoplastic and immunomodulatory properties in various cancers. This study investigated the impact of Vitamin D on the initiation and progression as well as antitumor immune response in HNSCCs, both in vitro and in vivo . An immunocompetent, orthotopic oral carcinogenesis mouse model was used to examine the influence of Vitamin D 3 substitution on HNSCC initiation and progression in vivo . Tumor immune infiltration was analyzed by immunohistochemistry targeting CD3, CD8, NKR-P1C, FOXP3, and CD163. Two HPV- and two HPV+ HNSCC cell lines were treated with 1,25-dihydroxyvitamin D 3 to analyze effects on tumor cell proliferation, migration and transcriptomic changes using RNA-sequencing, differential gene expression and gene set enrichment analysis. Vitamin D 3 treatment led to a significant suppression of HNSCC initiation and progression, while also stimulating tumor immune infiltration with CD3+, CD8+ and NKR-P1C+ cells and lowering levels of M2 macrophages and T reg cells in vivo . In vitro experiments showed an inhibition of HNSCC cell proliferation and migration in HPV+ and HPV- cell lines. RNA-sequencing showed significant regulations in IL6 JAK STAT3, hypoxia signaling and immunomodulatory pathways upon Vitamin D 3 treatment . The findings of our study highlight the promising potential of Vitamin D in the therapeutic repertoire for HNSCC patients given its immune modulating, anti-proliferative and anti-migratory properties. Clinical transferability of those in vitro and in vivo effects should be further validated in clinical trials. • Vitamin D inhibits proliferation and migration of HPV+ and HPV- HNSCC cells in vitro. • Vitamin D modulates hypoxia signaling and immunomodulatory pathways in HNSCC cells. • Vitamin D suppresses the induction of HNSCCs in a murine 4NQO oral carcinogenesis model. • Vitamin D increases the number of CD3+, CD8+ and NK cells in the TME of HNSCCs in vivo.