Background: Resistance to programmed cell death (apoptosis) is a crucial factor for the carcinogenesis of oral
squamous cell carcinoma (OSCC). Vitamin D (calcitriol) may overcome apoptosis resistance in tumor cells of
OSCC. Vitamin D receptor (VDR) expression in oral precancerous lesions of OSCC has not been analyzed and
serum vitamin D level seems to be a predictor of cancer development.
Material and Methods: Expression of VDR was analyzed in normal oral mucosa (n=5), oral precursor lesions
(simple hyperplasia, n=11; squamous intraepithelial neoplasia, SIN I-III, n=35), and OSCC specimen (n=42) by
immunohistochemistry (IHC). Moreover, serum vitamin D levels were measured by 25(OH)D3 (calcidiol) in patients with OSCC (n=42) and correlated with IHC results.
Results: Expression of VDR was significantly increased in precancerous and OSCC compared with normal tissue.
Compared with SIN I-III lesions VDR expression significantly decreased in OSCC. Severe vitamin D deficiency
was detected in our OSCC patient cohort but there was no significant correlation analyzed between serum vitamin
D levels and corresponding immunohistochemically detected VDR expression in OSCC.
Conclusions: Our survey provides the first evidence of VDR expression in precancerous lesions of OSCC. Apoptosis induction of VDR+ cells in oral precancerous lesions and OSCC by natural vitamin D or synthetic vitamin D
compounds could be useful for chemoprevention. Moreover, systemically and/or locally applied, these compounds
may act as sensitizers for apoptosis mediated by radio-, and chemotherapy treatment in OSCC
