In vitro effects of β-carotene on human oral keratinocytes from precancerous lesions and squamous carcinoma

Human keratinocytes, obtained from bioptic specimens of healthy and preneoplastic oral mucosa, and from human cell lines from oral cavity tumors (KB and SCC-25) were treated with β-carotene (10 μM). The colony forming efficiency (CFE), the proliferation rate and the frequency of micronucleated cells were measured in these cultures. CFE was significantly reduced (p < 0.05) by β-carotene treatment in cells from healthy mucosa and in KB cells. Decreases (p < 0.05; NS) were also observed in cells from pathological mucosa and in SCC-25 cells. Cell proliferation rate was not substantially affected by β-carotene in all cultures. Finally, a decreased frequency of micronucleated cells was found in treated cultures, but significant reductions (p < 0.05) were only observed in cultures from oral mucosa (healthy and pathological) as well as in KB cell cultures. Our results indicate that β-carotene is able to reduce the clonogenic activity (CFE), even if it does not seem to influence cell proliferation, and that it has a protective effect against genotoxic damage.