Overexpression of Mad transcription factor inhibits proliferation of cultured human hepatocellular carcinoma cells along with tumor formation in immunodeficient animals

J Gene Med. Mar-Apr 2000;2(2):117-27. doi: 10.1002/(SICI)1521-2254(200003/04)2:2<117::AID-JGM96>3.0.CO;2-X.


Background: Dominant negative regulation of critical cell cycle molecules could perturb survival of cancer cells and help develop novel therapies.

Methods: To perturb the activity of c-Myc, which regulates G0/G1 transitions, we overexpressed Mad1 protein with an adenoviral vector, AdMad. Studies were conducted with established cell lines, including HepG2, HuH-7 and PLC/PRF/5 liver cancer cells, RAT-1A embryonic fibroblasts and U373MG astrocytoma cells.

Results: After AdMad-treatment, transduced cells exhibited decreased proliferation rates in culture conditions. RAT-1A embryonic fibroblasts and U373MG astrocytoma cells showed accumulations in G0/G1, whereas HepG2 and HuH-7 cells accumulated in G0/G1, and additionally in G2/M, albeit to a lesser extent. An in vitro assay using hepatocyte growth factor to stimulate proliferation in HuH-7 cells showed blunting of growth factor responsiveness, along with inhibition of cell cycle progression in AdMad-treated cells. No cytotoxicity was observed in AdMad-treated cells in culture, although cells lost clonogenic capacity in soft agar. In vivo assays using HepG2 cell tumors in immunodeficient mice showed that overexpression of AdMad prevented tumorigenesis.

Conclusions: These studies indicate roles of Mad in G2/M, as well as the potential of manipulating cell cycle controls for treating liver cancer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Carcinoma, Hepatocellular / immunology
  • Carcinoma, Hepatocellular / pathology*
  • Cell Division
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Gene Transfer Techniques*
  • Genetic Vectors
  • Humans
  • Interphase
  • Liver Neoplasms / immunology
  • Liver Neoplasms / pathology*
  • Mice
  • Mice, SCID
  • Repressor Proteins*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Tumor Cells, Cultured


  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • DNA-Binding Proteins
  • MXD1 protein, human
  • Mad protein, mouse
  • Repressor Proteins
  • Transcription Factors