Galangin induces apoptosis in hepatocellular carcinoma cells through the caspase 8/t-Bid mitochondrial pathway

J Asian Nat Prod Res. 2012;14(7):626-33. doi: 10.1080/10286020.2012.682152. Epub 2012 May 10.

Abstract

This study has investigated whether galangin, a flavonol derived from Alpinia officinarum Hance and used as food additives in southern China, induces apoptosis in hepatocellular carcinoma cells (HCCs) by activation of the caspase-8 and Bid pathway. The apoptosis of HCCs was evaluated by in situ uptake of propidium iodide and Hoechst 33258. Protein expressions were detected by Western blotting. Caspase-8 activity was measured using colorimetric method. To confirm the galangin-induced apoptotic pathway, inhibition of caspase-8 activity by Z-IETD-FMK, knockdown of Bid expression with siRNA, and overexpression of Bcl-2 in cells were carried out, respectively. The results show that galangin has significantly induced apoptosis in HCC lines. The caspase-8 is activated, and the cleavage of Bid results in the increase in tBid. The galangin-induced apoptosis is attenuated by Z-IETD-FMK, Bid siRNA, and Bcl-2 overexpression, respectively. However, Bcl-2 fails to suppress caspase-8 activation and the cleavage of Bid. This study has demonstrated that galangin induces apoptosis in HCCs by activating caspase 8/t-Bid mitochondrial pathway. Although Bcl-2 overexpression attenuates galangin-mediated apoptosis of HCCs, it is not mediated by the inhibition of tBid generation and caspase-8 activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alpinia / chemistry
  • Apoptosis / drug effects*
  • Blotting, Western
  • Carcinoma, Hepatocellular / drug therapy*
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology
  • Caspase 8 / analysis
  • Caspase 8 / metabolism*
  • Flavonoids / pharmacology*
  • Flavonoids / therapeutic use
  • Hep G2 Cells
  • Humans
  • Liver / metabolism
  • Oligopeptides / pharmacology
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism

Substances

  • Flavonoids
  • Oligopeptides
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • benzyloxycarbonyl-isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone
  • galangin
  • Caspase 8