Flavokawain B inhibits growth of human squamous carcinoma cells: Involvement of apoptosis and cell cycle dysregulation in vitro and in vivo

Elong Lin, Wen Hsin Lin, Sheng Yang Wang, Chih Sheng Chen, Jiuun Wang Liao, Hsueh Wei Chang, Ssu Ching Chen, Kai Yuan Lin, Lai Wang, Hsin Ling Yang, You Cheng Hseu

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Flavokawain B is a natural chalcone isolated from the rhizomes of Alpenia pricei Hayata. In the present study, we have investigated the antiproliferative and apoptotic effect of flavokawain B (5-20 μg/ml; 17.6-70.4 μM) against human squamous carcinoma (KB) cells. Exposure of KB cells with flavokawain B resulted in apoptosis, evidenced by loss of cell viability, profound morphological changes, genomic DNA fragmentation and sub-G1 phase accumulation. Apoptosis induced by flavokawain B results in activation of caspase-9, -3 and -8, cleavage of poly ADP ribose polymerase (PARP) and Bid in KB cells. Flavokawain B also down-regulate Bcl-2 with concomitant increase in Bax level, which resulted in release of cytochrome c. Taken together, the induction of apoptosis by flavokawain B involved in both death receptor and mitochondrial pathway. We also observed that flavokawain B caused the G2/M phase arrest that was mediated through reductions in the levels of cyclin A, cyclin B1, Cdc2 and Cdc25C and increases in p21/WAF1, Wee1 and p53 levels. Moreover, flavokawain B significantly inhibits matrix metalloproteinase-9 and urokinase plasminogen activator expression, whereas tissue inhibitor of matrix metalloproteinase-1 and plasminogen activator inhibitor-1 were increased, which are playing critical role in tumor metastasis. In addition, flavokawain B treatment significantly inhibited in vivo growth of human KB cell-derived tumor xenografts in nude mice, which is evidenced by augmentation of apoptotic DNA fragmentation, as detected by in situ terminal deoxynucleotidyl transferase-meditated dUTP nick end-labeling staining. The induction of cell cycle arrest and apoptosis by flavokawain B may provide a pivotal mechanism for its cancer chemopreventive action.

Original languageEnglish
Pages (from-to)368-378
Number of pages11
JournalJournal of Nutritional Biochemistry
Issue number4
StatePublished - Apr 2012


  • Apoptosis
  • Cell cycle arrest
  • Flavokawain B
  • KB cells


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