title: Apigenin induces cell cycle arrest and p21/WAF1 expression in a p53-independent pathway.
abstract: Apigenin, a common dietary flavonoid, has been shown to induce cell growth-inhibition and cell cycle arrest in many cancer cell lines. One important effect of apigenin is to increase the stability of the tumor suppressor p53 in normal cells. Therefore, apigenin is expected to play a large role in cancer prevention by modifying the effects of p53 protein. However, the mechanisms of apigenin's effects on p53-mutant cancer cells have not been revealed yet. We assessed the influence of apigenin on cell growth and the cell cycle in p53-mutant cell lines. Treatment with apigenin resulted in growth-inhibition and G2/M phase arrest in two p53-mutant cancer cell lines, HT-29 and MG63. These effects were associated with a marked increase in the protein expression of p21/WAF1. We have shown that p21/WAF1 mRNA expression was also markedly increased by treatment with apigenin in a dose- and time-dependent manner. However, we could not detect p21/WAF1 promoter activity following treatment with apigenin. Similarly, promoter activity from pG13-Luc, a p53-responsive promoter plasmid, was not activated by treatment with apigenin with or without p53 protein expression. These results suggest that there is a p53-independent pathway for apigenin in p53-mutant cell lines, which induces p21/WAF1 expression and growth-inhibition. Apigenin may be a useful chemopreventive agent not only in wild-type p53 status, but also in cancer with mutant p53.
authors.affiliation: Department of Molecular-Targeting Cancer Prevention, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Takagaki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sowa
authors.forename: Teruki
authors.initials: T
authors.lastname: Oki
authors.forename: Ryoko
authors.initials: R
authors.lastname: Nakanishi
authors.forename: Shingo
authors.initials: S
authors.lastname: Yogosawa
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakai
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D047310:Apigenin / Q000494:pharmacology* / Q000627:therapeutic use; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D018890:Chemoprevention; D050759:Cyclin-Dependent Kinase Inhibitor p21; D006801:Humans; D009154:Mutation / Q000235:genetics; D009369:Neoplasms / Q000517:prevention & control; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*
chemical_list: D016588:Anticarcinogenic Agents; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D047310:Apigenin