Cell proliferation and drug resistance in hepatocellular carcinoma are modulated by Rho GTPase signals

Am J Physiol Gastrointest Liver Physiol. 2006 Apr;290(4):G624-32. doi: 10.1152/ajpgi.00128.2005. Epub 2005 Dec 1.

Abstract

Hepatocellular carcinoma is highly resistant to chemotherapeutic agents, thus the need to discover effective therapeutic molecules to suppress cancer cell growth and to overcome drug resistance is urgent. The Rho GTPase is implicated in cancer and metastasis and is directly activated by the Lymphoid blast crisis (Lbc) protooncogene, a Rho guanine-nucleotide exchange factor. The aim of the study was to analyze the expression of Lbc in hepatocarcinoma and to determine the effect of Lbc-induced Rho signaling on expression, growth rate and resistance to genotoxic stress. We found, by immunohistochemical analysis of biopsy samples and Northern and Western blot analyses of cell lines, that Lbc is absent in normal adult liver but is abundantly expressed in hepatocarcinoma, implying an increased Rho pathway signaling. Lbc stably transfected hepatocarcinoma cells exhibit increased proliferation and levels of ERK and cyclin D1 activation, which are blocked by a Rho inhibitor. In contrast, AKT activation was not altered. Moreover, Lbc expression confers increased resistance to genotoxic stress induced by doxorubicin, which is associated with upregulation of Bcl-2 and BAD phosphorylation, and this is reversed by a Rho inhibitor. In conclusion, these data support a role for Rho in liver cancer progression and resistance to therapy and may provide a basis for developing effective treatment for hepatocarcinoma.

Publication types

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

MeSH terms

  • A Kinase Anchor Proteins
  • Adaptor Proteins, Signal Transducing / metabolism
  • Antineoplastic Agents / administration & dosage
  • Carcinoma, Hepatocellular / drug therapy
  • Carcinoma, Hepatocellular / metabolism*
  • Carcinoma, Hepatocellular / pathology*
  • Cell Line, Tumor
  • Cell Proliferation
  • Dose-Response Relationship, Drug
  • Doxorubicin / administration & dosage*
  • Drug Resistance, Neoplasm*
  • Female
  • Gallbladder Neoplasms / drug therapy
  • Gallbladder Neoplasms / metabolism
  • Gallbladder Neoplasms / pathology
  • Humans
  • Liver / drug effects
  • Liver / metabolism
  • Liver / pathology
  • Liver Neoplasms / drug therapy
  • Liver Neoplasms / metabolism*
  • Liver Neoplasms / pathology*
  • Male
  • Minor Histocompatibility Antigens
  • Proto-Oncogene Proteins / metabolism
  • Signal Transduction / drug effects
  • rho GTP-Binding Proteins / metabolism*

Substances

  • A Kinase Anchor Proteins
  • AKAP13 protein, human
  • Adaptor Proteins, Signal Transducing
  • Antineoplastic Agents
  • Minor Histocompatibility Antigens
  • Proto-Oncogene Proteins
  • Doxorubicin
  • rho GTP-Binding Proteins