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Proteins that bind the Src homology 3 domain of CrkI have distinct roles in Crk transformation

J Zheng1, K Machida, S Antoku

  • 1Raymond and Beverly Sackler Laboratory of Genetics and Molecular Medicine, Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06030-6403, USA.

Oncogene
|August 24, 2010
PubMed

Insights

CrkI protein transformation of fibroblasts requires SOS1, a guanine nucleotide exchange protein. Abl kinases surprisingly inhibit CrkI-induced transformation and tumor formation.

Area of Science:

  • Oncogene biology
  • Cellular transformation
  • Cancer research

Background:

  • The v-Crk oncogene and its cellular homolog CrkI possess Src homology 2 (SH2) and Src homology 3 (SH3) domains.
  • CrkI overexpression transforms mouse fibroblasts and is implicated in human cancers.
  • Crk's SH2 and SH3 domains are crucial for transformation, but binding partners remain unidentified.

Purpose of the Study:

  • To identify essential cellular binding partners required for CrkI-induced fibroblast transformation.
  • To elucidate the roles of candidate Crk SH3-binding proteins, including C3G, SOS1, DOCK180, and Abl kinases.

Main Methods:

  • Short hairpin RNA (shRNA)-mediated knockdown of candidate binding partners in NIH-3T3 cells.
  • Assessment of anchorage-independent growth and morphological changes.
  • Evaluation of tumor formation in nude mice.
  • Inhibition of Abl family kinases using imatinib.

Main Results:

  • Knockdown of C3G or SOS1 suppressed anchorage-independent growth of CrkI-overexpressing NIH-3T3 cells.
  • SOS1 knockdown alone suppressed tumor formation in vivo.
  • C3G knockdown reverted CrkI-induced morphological changes.
  • Abl kinase inhibition or knockdown enhanced anchorage-independent growth and tumorigenesis.

Conclusions:

  • SOS1 is essential for CrkI-induced fibroblast transformation.
  • Abl kinases play a negative regulatory role in Crk-mediated transformation.
  • These findings identify key molecular players in Crk oncogene-driven cellular changes.

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