Luteolin synergizes the antitumor effects of 5-fluorouracil against human hepatocellular carcinoma cells through apoptosis induction and metabolism

Life Sci. 2016 Jan 1:144:138-47. doi: 10.1016/j.lfs.2015.12.002. Epub 2015 Dec 2.

Abstract

Aims: Some compounds derived from Chinese medicine have demonstrated great prospective roles in sensitization to chemotherapy. This study aimed to investigate the combination of luteolin and 5-fluorouracil on proliferations of hepatocellular carcinoma cells and the potential mechanisms.

Main methods: The antitumor effects of luteolin, 5-fluorouracil, and their combinations were detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium/phenazine methosulfate assay, and isobole method was used to evaluate drug combinations. CellTiter-Blue and Caspase-Glo 3/7 assay were used for assessment of cell viability and apoptosis after treatment with luteolin, 5-fluorouracil and their combinations. Cell cycle distributions and apoptosis were detected by PI staining, Hoechst 33342 staining and FITC-Annexin V/PI staining. Bcl-2, bax, p53 and PARP expressions were determined by Western blot. Furthermore, mRNA levels of 5-fluorouracil metabolism related enzymes were detected by RT-PCR.

Key findings: Drug combination study showed that luteolin could synergize the antitumor effects of 5-fluorouracil at different dose ratios (luteolin: 5-fluorouracil=10:1, 20:1, 40:1) against HepG2 and Bel7402 cells. Cell viability and cell apoptosis analysis showed that the synergistic growth inhibition caused by combined luteolin and 5-fluorouracil was closely related to apoptosis. Further mechanism studies showed that the synergistic effects of drug combinations were related with enhanced bax/bcl-2 ratios and p53 expressions, and induced PARP cleavage. Also, combined luteolin and 5-fluorouracil could significantly decrease the dihydropyrimidine dehydrogenase.

Significance: These results showed that luteolin could synergize the antitumor effects of 5-fluorouracil on HepG2 and Bel7402 cells, which might be related with apoptosis and regulation of 5-fluorouracil metabolism.

Keywords: 5-Fluorouracil; Apoptosis; Hepatocellular carcinoma; Luteolin; Synergistic effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / pharmacology*
  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / biosynthesis
  • Apoptosis Regulatory Proteins / genetics
  • Cell Cycle / drug effects
  • Cell Line, Tumor
  • Dihydrouracil Dehydrogenase (NADP) / antagonists & inhibitors
  • Drug Synergism
  • Fluorouracil / pharmacology*
  • Humans
  • Liver Neoplasms, Experimental / drug therapy*
  • Liver Neoplasms, Experimental / metabolism*
  • Liver Neoplasms, Experimental / pathology
  • Luteolin / pharmacology*
  • Membrane Potential, Mitochondrial / drug effects
  • Prospective Studies
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics

Substances

  • Antimetabolites, Antineoplastic
  • Apoptosis Regulatory Proteins
  • RNA, Messenger
  • Dihydrouracil Dehydrogenase (NADP)
  • Luteolin
  • Fluorouracil