Water extract of Hedyotis Diffusa Willd suppresses proliferation of human HepG2 cells and potentiates the anticancer efficacy of low-dose 5-fluorouracil by inhibiting the CDK2-E2F1 pathway

Oncol Rep. 2012 Aug;28(2):742-8. doi: 10.3892/or.2012.1834. Epub 2012 May 25.

Abstract

Hedyotis Diffusa Willd (HDW), a Chinese herbal medicine, has been widely used as an adjuvant therapy against various cancers, including hepatocellular carcinoma (HCC). However, the underlying anticancer mechanisms are yet to be elucidated. In the present study, the anticancer effects of HDW were evaluated and the efficacy and safety of HDW combined with low-dose 5-fluorouracil (5-FU) were investigated. HepG2 cells were cultured in vitro and nude mouse xenografts were established in vivo. The proliferation of HepG2 cells was measured using the MTT method and flow cytometry. The mRNA and protein expression levels of cyclin-dependent kinase 2 (CDK2), cyclin E and E2F1 were examined using relative quantitative real-time PCR and western blot analysis, respectively. The results showed that water extract of HDW remarkably inhibited HepG2 cell proliferation in a dose-dependent manner via arrest of HepG2 cells at the G0/G1 phase and induction of S phase delay. This suppression was accompanied by a great decrease of E2F1 and CDK2 mRNA expression. In addition, HDW remarkably potentiated the anticancer effect of low-dose 5-FU in the absence of overt toxicity by downregulating the mRNA and protein levels of CDK2, cyclin E and E2F1. Our findings support the use of HDW as adjuvant therapy of chemotherapy and suggest that HDW may potentiate the efficiency of low-dose 5-FU in treating HCC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Carcinoma, Hepatocellular / drug therapy*
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology
  • Cell Growth Processes / drug effects
  • Cell Line, Tumor
  • Cyclin-Dependent Kinase 2 / antagonists & inhibitors*
  • Cyclin-Dependent Kinase 2 / genetics
  • Cyclin-Dependent Kinase 2 / metabolism*
  • Dose-Response Relationship, Drug
  • Drug Synergism
  • E2F1 Transcription Factor / antagonists & inhibitors*
  • E2F1 Transcription Factor / genetics
  • E2F1 Transcription Factor / metabolism
  • Female
  • Fluorouracil / administration & dosage
  • Fluorouracil / pharmacology*
  • G1 Phase Cell Cycle Checkpoints / drug effects
  • Hedyotis / chemistry*
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / drug therapy*
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Plant Extracts / administration & dosage
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology*
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Resting Phase, Cell Cycle / drug effects
  • S Phase / drug effects
  • Water / chemistry
  • Xenograft Model Antitumor Assays

Substances

  • E2F1 Transcription Factor
  • E2F1 protein, human
  • Plant Extracts
  • RNA, Messenger
  • Water
  • CDK2 protein, human
  • Cyclin-Dependent Kinase 2
  • Fluorouracil