Novel roles of galectin-1 in hepatocellular carcinoma cell adhesion, polarization, and in vivo tumor growth

Hepatology. 2011 Jun;53(6):2097-106. doi: 10.1002/hep.24294.

Abstract

Galectin-1 (Gal-1), a widely expressed β-galactoside-binding protein, exerts pleiotropic biological functions. Gal-1 is up-regulated in hepatocarcinoma cells, although its role in liver pathophysiology remains uncertain. We investigated the effects of Gal-1 on HepG2 hepatocellular carcinoma (HCC) cell adhesion and polarization. Soluble and immobilized recombinant Gal-1 (rGal-1) promoted HepG2 cell adhesion to uncoated plates and also increased adhesion to laminin. Antibody-mediated blockade experiments revealed the involvement of different integrins as critical mediators of these biological effects. In addition, exposure to rGal-1 markedly accelerated the development of apical bile canaliculi as shown by TRITC-phalloidin labeling and immunostaining for multidrug resistance associated-protein 2 (MRP2). Notably, rGal-1 did not interfere with multidrug resistance protein 1/P-glycoprotein or MRP2 apical localization, neither with transfer nor secretion of 5-chloromethylfluorescein diacetate through MRP2. Stimulation of cell adhesion and polarization by rGal-1 was abrogated in the presence of thiodigalactoside, a galectin-specific sugar, suggesting the involvement of protein-carbohydrate interactions in these effects. Additionally, Gal-1 effects were abrogated in the presence of wortmmanin, PD98059 or H89, suggesting involvement of phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinase and cyclic adenosine monophosphate-dependent protein kinase signaling pathways in these functions. Finally, expression levels of this endogenous lectin correlated with HCC cell adhesion and polarization and up-regulation of Gal-1-favored growth of hepatocarcinoma in vivo.

Conclusion: Our results provide the first evidence of a role of Gal-1 in modulating HCC cell adhesion, polarization, and in vivo tumor growth, with critical implications in liver pathophysiology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Hepatocellular / physiopathology*
  • Cell Adhesion / physiology
  • Cell Line, Tumor
  • Cell Polarity / physiology*
  • Cell Proliferation*
  • Cyclic AMP-Dependent Protein Kinases / physiology
  • Galectin 1 / physiology*
  • Humans
  • Liver Neoplasms / physiopathology*
  • Mitogen-Activated Protein Kinases / physiology
  • Multidrug Resistance-Associated Proteins / physiology
  • Phosphatidylinositol 3-Kinases / physiology
  • Signal Transduction / physiology

Substances

  • Galectin 1
  • Multidrug Resistance-Associated Proteins
  • multidrug resistance-associated protein 2
  • Phosphatidylinositol 3-Kinases
  • Cyclic AMP-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinases