Crk Tyrosine Phosphorylation Regulates PDGF-BB-inducible Src Activation and Breast Tumorigenicity and Metastasis

Mol Cancer Res. 2018 Jan;16(1):173-183. doi: 10.1158/1541-7786.MCR-17-0242. Epub 2017 Oct 3.


The activity of Src family kinases (Src being the prototypical member) is tightly regulated by differential phosphorylation on Tyr416 (positive) and Tyr527 (negative), a duet that reciprocally regulates kinase activity. The latter negative regulation of Src on Tyr527 is mediated by C-terminal Src kinase (CSK) that phosphorylates Tyr527 and maintains Src in a clamped negative regulated state by promoting an intramolecular association. Here it is demonstrated that the SH2- and SH3-domain containing adaptor protein CrkII, by virtue of its phosphorylation on Tyr239, regulates the Csk/Src signaling axis to control Src activation. Once phosphorylated, the motif (PIpYARVIQ) forms a consensus sequence for the SH2 domain of CSK to form a pTyr239-CSK complex. Functionally, when expressed in Crk-/- MEFs or in Crk+/+ HS683 cells, Crk Y239F delayed PDGF-BB-inducible Src Tyr416 phosphorylation. Moreover, expression of Crk Y239F in HS683 cells delayed Src kinase activation and suppressed the cell-invasive and -transforming phenotypes. Finally, through loss-of-function and epistasis experiments using CRISPR-Cas9-engineered 4T1 murine breast cancer cells, Crk Tyr239 is implicated in breast cancer tumor growth and metastasis in orthotopic immunocompetent 4T1 mice model of breast adenocarcinoma. These findings delineate a novel role for Crk Tyr239 phosphorylation in the regulation of Src kinases, as well as a potential molecular explanation for a long-standing question as to how Crk regulates the activation of Src kinases.Implications: These findings provide new perspectives on the versatility of Crk in cancer by demonstrating how Crk mechanistically drives, through a tyrosine phosphorylation-dependent manner, tumor growth, and metastasis. Mol Cancer Res; 16(1); 173-83. ©2017 AACR.

Publication types

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

MeSH terms

  • Animals
  • Becaplermin / metabolism*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • Female
  • HEK293 Cells
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • NIH 3T3 Cells
  • Neoplasm Metastasis
  • Phosphorylation
  • Proto-Oncogene Proteins c-crk / metabolism*
  • Signal Transduction
  • src-Family Kinases / metabolism


  • CRK protein, human
  • Crk protein, mouse
  • Proto-Oncogene Proteins c-crk
  • Becaplermin
  • src-Family Kinases