Journal Article

Gab1 but not Grb2 mediates tumor progression in Met overexpressing colorectal cancer cells

Isolde Seiden-Long, Roya Navab, Warren Shih, Ming Li, Jane Chow, Chang Qi Zhu, Nikolina Radulovich, Caroline Saucier and Ming-Sound Tsao

in Carcinogenesis

Volume 29, issue 3, pages 647-655
Published in print March 2008 | ISSN: 0143-3334
Published online January 2008 | e-ISSN: 1460-2180 | DOI:
Gab1 but not Grb2 mediates tumor progression in Met overexpressing colorectal cancer cells

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Hepatocyte growth factor receptor (Met) plays an important role in the progression of multiple cancer types. The overexpression of Met in DLD-1 colon carcinoma cells with kirsten rat sarcoma oncogene homolog (KRAS) oncogene activation resulted in enhanced subcutaneous and orthotopic tumor growth rate and increased metastatic potential. To elucidate the mechanism of this effect, we stably expressed kinase-inactive MetK1110A, Src homology 2 (SH2)-binding domain-inactive MetY1349/1356F, growth factor receptor-bound protein 2 (Grb2) non-binding MetN1358H and mutant receptors with ability to selectively recruit signaling proteins Grb2, src homology domain c-terminal adaptor homolog (Shc), phospholipase c-gamma (PLCγ) and p85 phosphatidyl inositol 3 kinase. As subcutaneous implants, DLD-1 cells that expressed the majority of these receptor constructs failed to recapitulate the tumor growth-enhancing effect of the wild-type Met receptor. The Grb2- and Shc-recruiting Met mutants demonstrated slight but consistent tumor-suppressive activity, whereas the expression of N1358H mutant stimulated tumor growth rate comparable with the wild-type receptor. This suggests that direct Grb2/Shc binding does not contribute to the tumor progression activity of Met receptor. The tumors expressing Grb2- and Shc-recruiting Met receptors demonstrated a marked loss in Grb2-associated adaptor protein 1 (Gab1) protein levels, which was not observed in the cell lines, consistent with a post-translationally regulated process. Moreover, a moderate level of Gab1 overexpression stimulated tumor growth. The findings suggest a delicate balance for intact Y1349/1356 SH2-binding domain to mediate the tumor progression activity of the coactivated Met–rat sarcoma oncogene homolog (RAS) pathways. Selectivity for specific adaptor protein involvement may be the key that determines the tissue- and cell-type specificity of Met-mediated tumorigenicity in human cancers.

Journal Article.  6521 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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