Early effects of retinoic acid on proliferation, differentiation and apoptosis in non-small cell lung cancer cell lines

Background: Retinoids represent a potentially useful class of drugs in the chemoprevention and treatment of cancer, due to their ability to regulate c ell proliferation and differentiation. However; there is controversy in the literature about the effects of all-trans retinoic acid (ATRA) in non- sma ll cell lung cancer (NSCLC). In this study we examined the effects of ATRA on apoptotic death in NSCLC. Materials and Methods: Cell proliferation was determined by thymidine incorporation in cultured NSCLC cells. DNA fragment ation was measured in NSCLC cell lines as a marker of apoptosis. The expres sion of keratinocyte transglutaminase and cytokeratin 10 were measured as m arkers of squamous differentiation. Results: A TRA inhibited cell prolifera tion, and induced markers of both apoptosis and squamous differentiation af ter 24-48 hrs of treatment. Conclusions: These results indicate the possibi lity of the early growth-inhibitory and apoptotic effects of ATRA in NSCLC which may result in selection of ATRA-resistant cells.