**Mirela Ibrahimovic 1,2, Elizabeth Franzmann 3,4, Alison M. Mondul 1,2, Katherine M. Weh 1,5, Connor Howard 1,5, Jennifer J. Hu 3,6, W. Jarrard Goodwin 3,6 and Laura A. Kresty 1,5,\***


Received: 31 July 2020; Accepted: 26 August 2020; Published: 29 August 2020

**Abstract:** Blacks experience disproportionate head and neck cancer (HNC) recurrence and mortality compared to Whites. Overall, vitamin D status is inversely associated to HNC pointing to a potential protective linkage. Although hypovitaminosis D in Blacks is well documented it has not been investigated in Black HNC patients. Thus, we conducted a prospective pilot study accessing vitamin D status in newly diagnosed HNC patients stratified by race and conducted in vitro studies to investigate mechanisms associated with potential cancer inhibitory effects of vitamin D. Outcome measures included circulating levels of vitamin D, related nutrients, and risk factor characterization as well as dietary and supplemental estimates. Vitamin D-based in vitro assays utilized proteome and microRNA (miR) profiling. Nineteen patients were enrolled, mean circulating vitamin D levels were significantly reduced in Black compared to White HNC patients, 27.3 and 20.0 ng/mL, respectively. Whites also supplemented vitamin D more frequently than Blacks who had non-significantly higher vitamin D from dietary sources. Vitamin D treatment of HNC cell lines revealed five significantly altered miRs regulating genes targeting multiple pathways in cancer based on enrichment analysis (i.e., negative regulation of cell proliferation, angiogenesis, chemokine, MAPK, and WNT signaling). Vitamin D further altered proteins involved in cancer progression, metastasis and survival supporting a potential role for vitamin D in targeted cancer prevention.

**Keywords:** head and neck cancer; racial disparities; vitamin D; chemoprevention; UVB; microRNA; proteomic profiling
