Role of p21WAF1 in green tea polyphenol-induced growth arrest and apoptosis of oral carcinoma cells
Hsu, S.; Farrey, K.; Wataha, J.; Lewis, J.; Borke, J.; Singh, B.; Qin, H.; Lapp, C.; Lapp, D.; Nguyen, T.; Schuster, G.
Anticancer Research 25(1a): 63-67
2005
ISSN/ISBN: 0250-7005 PMID: 15816520 Document Number: 591601
The cyclin-dependent kinase inhibitor p21(WAF1) participates in cell growth, differentiation and apoptosis. p21(WAF1) can be induced by green tea polyphenol EGCG in several cancer cell types, but its role in the oral cancer cell response to EGCG is not known. We found that EGCG upregulates p21(WAF1) in an oral carcinoma cell line, OSC2, by cDNA microarray. The current study determined the impact of siRNA-suppressed p21(WAF1) and its response to EGCG on cell growth, DNA synthesis and apoptosis by RT-PCR, Western blot, BrdU incorporation, MTT and caspase 3 activity assays. Suppression of p21(WAF1) by siRNA resulted in an accelerated cell growth and DNA synthesis, and increased cell viability. However, caspase 3 activity was not significantly inhibited. The evidence showed that p21(WAF1) is involved in EGCG-induced growth arrest of OSC2 cells, which may facilitate caspase 3-mediated apoptosis. Thus, expression of functional p21(WAF1) may promote phytochemical-mediated growth arrest and apoptosis in oral carcinoma cells.