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IGF1R signaling in Ewing sarcoma is shaped by clathrin-/caveolin-dependent endocytosis

Ana Sofia Martins1, José Luis Ordóñez, Ana Teresa Amaral

  • 1Laboratory 20-Molecular Pathology of Sarcomas Laboratory, Centro de Investigación del Cáncer-IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain.

Plos One
|May 26, 2011
PubMed

Insights

Inhibiting Insulin-like Growth Factor 1 Receptor (IGF1R) internalization via clathrin or caveolin-1 (CAV1) pathways reduces Ewing Sarcoma cell growth and increases apoptosis. Combining IGF1R inhibitors with endocytosis blockers enhances these anti-cancer effects.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Cancer Signaling

Background:

  • Receptor endocytosis is crucial for cellular signaling pathways.
  • The Insulin-like Growth Factor 1 Receptor (IGF1R) plays a key role in Ewing Sarcoma (ES) cell survival through an autocrine loop.
  • IGF1R internalization, mediated by clathrin and caveolin-1 (CAV1), is implicated in ES signaling.

Purpose of the Study:

  • To investigate the impact of IGF1R internalization, dependent on clathrin and CAV1, on Ewing Sarcoma signaling.
  • To evaluate the effects of inhibiting IGF1R endocytosis on ES cell proliferation and apoptosis.
  • To explore the potential of combining IGF1R inhibitors with endocytosis inhibitors as a therapeutic strategy.

Main Methods:

  • Utilized clathrin and CAV1-siRNA to disrupt clathrin- and caveolin-dependent endocytosis.
  • Employed chlorpromazine (CPMZ) and methyl-beta-cyclo-dextrin (MCD) to inhibit clathrin- and caveolin-dependent endocytosis, respectively.
  • Analyzed IGF1R internalization, co-localization with clathrin/CAV1, signaling pathway status (AKT, MAPK), proliferation, and apoptosis. Performed high-throughput tyrosine kinase phosphorylation assays.

Main Results:

  • IGF1R internalization in ES cells upon ligand binding was confirmed to be dependent on clathrin or CAV1.
  • Blocking IGF1R internalization significantly inhibited AKT and MAPK phosphorylation, reduced cellular proliferation, and increased apoptosis.
  • Combining the IGF1R inhibitor AEW541 (AEW) with CPMZ or MCD markedly enhanced these inhibitory effects.

Conclusions:

  • Clathrin and CAV1-mediated endocytosis critically control IGF1R internalization and downstream signaling in Ewing Sarcoma.
  • Inhibition of IGF1R internalization profoundly impacts ES cell survival signaling.
  • The combination of tyrosine-kinase inhibitors with endocytosis inhibitors presents a promising therapeutic approach for neoplasms reliant on IGF1R signaling.

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