No abstract

Small GTPases, particularly the Rho family, are key regulators of cell motility and migration. Dock180 was well known for the main target of signal adaptor protein Crk and acted as a guanine-nucleotide exchange factor for small GTPase Rac1. In the present study, Dock180 was found to combine primarily with CrkI other than CrkII, and its association with Elmo1 was also demonstrated in ovarian cancer cell SKOV3. To evaluate the role of Dock180 in human ovarian cancer cell, we performed RNAi-mediated knockdown of Dock180 in SKOV3 cells using small interfering RNA expression vector. In Dock180 knockdown cells, we found that Elmo1 expression and Rac1 activity were decreased simultaneously. By contrast, the expressions of both another Crk-combining molecule C3G and Rap1 activity were observed to increase obviously. Accordingly, all Dock180 knockdown cells present with evident change in cell morphology, reduced cell proliferation, and attenuated cell migration. Taken together, these results suggest that signal transfer of Crk/Dock180/Rac1 is implicated in actin cytoskeleton reorganization and thus in the cell proliferation, motility, invasion, and of human ovarian cancer cell line SKOV3.

Engulfment and cell motility 1 presents with synergetic action in helping Dock180 to activate Rac1 and promote cell motility, and thus promote untoward expansion and aggressiveness of SOC.

Adaptor protein Crk and CrkL were thought to be closely related because both consist of one SH2 and two SH3 domains and share 60% homology with the highest identity within their functional domains. Their functions were most presumed to be in part, if not all, redundant. And both were suggested to be implicated in carcinogenesis. In this study, both Crk and CrkL presented with much higher expression in ovarian cancer tissues than those in normal and benign ovarian tissues. However, in contrast with CrkL, high Crk expression displayed close association with advanced stages and high-grade diseases. Furthermore, the differential binding selectivity of Crk and CrkL to their downstream partners Dock 180 and C3G was demonstrated in ovarian cancer cell line SKOV3 through coimmunoprecipitation. Additionally, Crk-knockdown cells presented with changed morphology, reduced growth, and cell invasion but remained viable. In contrast, all CrkL-knockdown cells could not survive over time, gradually detaching from the bottom of plastic dish. In conclusion, these two highly homologous proteins hold features that allow for the differential association with each binding molecules, thereby activating different signaling pathways and being involved in diverse roles in ovarian cancer.