BMP4-Smad signaling pathway mediates adriamycin-induced premature senescence in lung cancer cells.

Cell senescence, an irreversible cell cycle arrest, reflects a safeguard program that limits the capacity of uncontrolled cell proliferation. Treatment of tumor cells with certain chemotherapeutic agents activates premature senescence to decrease the tumorigenecity. Here we show that sublethal concentrations of adriamycin could induce premature senescence in lung cancer cells. Adriamycin treatment resulted in the up-regulation of BMP4, which is underexpressed in NSCLC (non-small cell lung cancers). Moreover, the BMP4-Smad pathway played a key role in mediating adriamycin-induced senescence. Overexpression of BMP4 was able to induce premature senescence in lung cancer cells and this process required the participation of cyclin/cyclin-dependent kinase (cdk) inhibitors p16(INK4a) and p21(WAF1/cip1). We also show that increases of p16(INK4a) and p21(WAF1/cip1) expression in response to BMP4 were mediated by the Smad signaling pathway. Furthermore, our data revealed that p300 was recruited to P16(INK4a) and P21(WAF1/cip1) promoters by Smad1/5/8 to induce the hyperacetylation of histones H3 and H4 at the promoters. The present study provides useful clues to the evaluation of the potentiality of BMP4 as a responsive molecular target for cancer chemotherapy.