title: Role of p21WAF1 in green tea polyphenol-induced growth arrest and apoptosis of oral carcinoma cells.
abstract: The cyclin-dependent kinase inhibitor p21WAF1 participates in cell growth, differentiation, and apoptosis. p21WAF1 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 p21WAF1 in an oral carcinoma cell line, OSC2, by cDNA microarray. The current study determined the impact of siRNA-suppressed p21WAF1 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 p21WAF1 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 p21WAF1 is involved in EGCG-induced growth arrest of OSC2 cells, which may facilitate caspase 3-mediated apoptosis. Thus, expression of functional p21WAF1 may promote phytochemical-mediated growth arrest and apoptosis in oral carcinoma cells.
authors.affiliation: Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, GA 30912-1126, USA. shsu@mail.mcg.edu
authors.forename: Stephen
authors.initials: S
authors.lastname: Hsu
authors.forename: Kajuana
authors.initials: K
authors.lastname: Farrey
authors.forename: John
authors.initials: J
authors.lastname: Wataha
authors.forename: Jill
authors.initials: J
authors.lastname: Lewis
authors.forename: James
authors.initials: J
authors.lastname: Borke
authors.forename: Baldev
authors.initials: B
authors.lastname: Singh
authors.forename: Haiyan
authors.initials: H
authors.lastname: Qin
authors.forename: Carol
authors.initials: C
authors.lastname: Lapp
authors.forename: David
authors.initials: D
authors.lastname: Lapp
authors.forename: Tuan
authors.initials: T
authors.lastname: Nguyen
authors.forename: George
authors.initials: G
authors.lastname: Schuster
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001973:Bromodeoxyuridine / Q000378:metabolism; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects; D009062:Mouth Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D013662:Tea; D013778:Tetrazolium Salts; D013844:Thiazoles; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013662:Tea; D013778:Tetrazolium Salts; D013844:Thiazoles; D002392:Catechin; C045651:epigallocatechin gallate; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C022616:thiazolyl blue; D001973:Bromodeoxyuridine