Resveratrol selectively induces DNA Damage, independent of Smad4 expression, in its efficacy against human head and neck squamous cell carcinoma.

Purpose: Alterations in Smad4 signaling and its loss cause genomic instability and head and neck squamous cell carcinoma (HNSCC), suggesting that agents that target both Smad4-dependent and -independent pathways could control HNSCC.

Experimental Design: Resveratrol efficacy was evaluated against the HNSCC cells FaDu, Cal27, Det562, and Cal27-Smad4 for viability, DNA damage, cell-cycle progression, and apoptosis, as well as γ-H2AX expression, and focus formation (γ-H2AX and Brca1). Resveratrol efficacy was also examined in nude mice for FaDu xenograft growth. Xenografts were analyzed for γ-H2AX and cleaved caspase-3.

Results: Resveratrol (5-50 μmol/L) suppressed viability and induced DNA damage in FaDu and Cal27 cells but not in normal human epidermal keratinocytes and human foreskin fibroblasts, showing its selectivity toward HNSCC cells; however, Det562 cells were resistant to resveratrol even at 100 μmol/L. Cal27 cells stably transfected with Smad4 showed similar resveratrol effects as parental Cal27, indicating that a lack of resveratrol effect in Det562 cells was independent of Smad4 status in these cells. Furthermore, resveratrol caused S-phase arrest and apoptotic death of FaDu and Cal27 cells together with induction of Brca1 and γ-H2AX foci. Resveratrol (50 mg/kg body weight) treatment also inhibited FaDu tumor growth in nude mice, and γ-H2AX and cleaved caspase-3 were strongly increased in xenografts from resveratrol-treated mice compared with controls.

Conclusion: Our findings for the first time showed antiproliferative, DNA damaging, and apoptotic effects of resveratrol in HNSCC cells independent of Smad4 status, both in vitro and in vivo, suggesting that more studies are needed to establish its potential usefulness against HNSCC.