A role of LIM kinase 1/cofilin pathway in regulating endocytic trafficking of EGF receptor in human breast cancer cells

Histochem Cell Biol. 2006 Nov;126(5):627-38. doi: 10.1007/s00418-006-0198-x. Epub 2006 Jun 9.

Abstract

We have previously shown that overexpression of LIM kinase1 (LIMK1) resulted in a marked retardation of the internalization of the receptor-mediated endocytic tracer, Texas red-labeled epidermal growth factor (EGF) in low-invasive human breast cancer cell MCF-7. We thereby postulate that LIMK1 signaling plays an important role in the regulation of ligand-induced endocytosis of EGF receptor (EGFR) in tumor cells by reorganizing and influencing actin-filament dynamics. In the present study, we further assessed the effect of wild-type LIMK1, a kinase-deficient dominant negative mutant of LIMK1 (DN-LIMK1) and an active, unphosphorylatable cofilin mutant (S3A cofilin) on internalization of EGF-EGFR in MDA-MB-231, a highly invasive human breast cancer cell line. We demonstrate here that a marked delay in the receptor-mediated internalization of Texas red-labeled EGF was observed in the wild-type LIMK1 transfectants, and that most of the internalized EGF staining were accumulated within transferrin receptor-positive early endosomes even after 30 min internalization. In contrast, the expression of dominant-negative LIMK1 mutant rescued the efficient endocytosis of Texas red-EGF, and large amounts of Texas red-EGF staining already reached LIMPII-positive late endosomes/lysosomal vacuoles after 15 min internalization. We further analyzed the effect of S3A cofilin mutant on EGFR trafficking, and found an efficient delivery of Texas red-EGF into late endosomes/lysosomes at 15-30 min after internalization. Taken together, our novel findings presented in this paper implicate that LIMK1 signaling indeed plays a pivotal role in the regulation of EGFR trafficking through the endocytic pathway in invasive tumor cells.

MeSH terms

  • Actin Depolymerizing Factors / genetics
  • Actin Depolymerizing Factors / physiology*
  • Breast Neoplasms / metabolism*
  • Cathepsin D / metabolism
  • Endocytosis / physiology*
  • ErbB Receptors / metabolism*
  • Female
  • Humans
  • Immunoblotting
  • Lim Kinases
  • Lysosome-Associated Membrane Glycoproteins / metabolism
  • Protein Kinases / physiology*
  • Protein Transport
  • Receptors, Scavenger / metabolism
  • Signal Transduction
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Actin Depolymerizing Factors
  • Lysosome-Associated Membrane Glycoproteins
  • Receptors, Scavenger
  • SCARB2 protein, human
  • Protein Kinases
  • ErbB Receptors
  • LIMK1 protein, human
  • Lim Kinases
  • Cathepsin D