Adaptor Molecule Crk Is Required for Sustained Phosphorylation of Grb2-Associated Binder 1 and Hepatocyte Growth Factor–Induced Cell Motility of Human Synovial Sarcoma Cell Lines

Abstract

Activation of the c-Met receptor tyrosine kinase through its ligand, hepatocyte growth factor (HGF), promotes mitogenic, motogenic, and morphogenic cellular responses. Aberrant HGF/c-Met signaling has been strongly implicated in tumor cell invasion and metastasis. Both HGF and its receptor c-Met have been shown to be overexpressed in human synovial sarcoma, which often metastasizes to the lung; however, little is known about HGF-mediated biological effects in this sarcoma. Here, we provide evidence that Crk adaptor protein is required for the sustained phosphorylation of c-Met-docking protein Grb2-associated binder 1 (Gab1) in response to HGF, leading to the enhanced cell motility of human synovial sarcoma cell lines SYO-1, HS-SY-II, and Fuji. HGF stimulation induced the sustained phosphorylation on Y307 of Gab1 where Crk was recruited. Crk knockdown by RNA interference disturbed this HGF-induced tyrosine phosphorylation of Gab1. By mutational analysis, we identified that Src homology 2 domain of Crk is indispensable for the induction of the phosphorylation on multiple Tyr-X-X-Pro motifs containing Y307 in Gab1. HGF remarkably stimulated cell motility and scattering of synovial sarcoma cell lines, consistent with the prominent activation of Rac1, extreme filopodia formation, and membrane ruffling.

Integrin signalling adaptors: not only figurants in the cancer story

“…CRK silencing remarkably suppresses tumour formation in human synovial sarcoma cell xenografts and invasive growth in vivo 91,92 . In glioblastoma cells, CRK over-expression increases cell migration and invasion, likely through an association with DOCK180 26 and its silencing suppresses early attachment to laminin, cell motility and growth 27 .…”

Fibroblast Growth Requires CT10 Regulator of Kinase (Crk) and Crk-like (CrkL)

“…Overexpression of Crk and CrkL has been reported in several human cancers, including oral squamous cell carcinoma (5), ovarian carcinoma (6), colon cancer (7), lung cancer (8,9), breast cancer (10,11), gastric cancer (12), and glioblastoma (13,14). Reduced expression of either Crk or CrkL by RNA interference-mediated knockdown lowered the in vivo tumor formation of human ovarian (15), synovial sarcoma (16), glioblastoma (14), breast cancer (10), head and neck squamous cell carcinoma (17), and rhabdomyosarcoma (18) cell lines. Taken together, these reports imply that elevated levels of Crk family proteins promote cell transformation and enhance tumor cell growth (for review see Refs.…”

Synovial Sarcoma: From Genetics to Genetic-based Animal Modeling

“…This is important because certain crucial therapeutically vulnerable elements of a pathway may lie upstream or downstream to the primary molecular aberration, precluding its identification in expression/mutation-based analyses. Several studies have suggested involvement of the architecture-regulating ephrin pathway and signaling pathways such as Wnt, IGF, ERBB2, HGF/MET, and b-catenin in synovial sarcoma [2,4,47,62,78,82,84]. New studies continue to provide further insight into how such pathways are involved in certain facets of the tumor phenotype.…”