Inactivation of Rho GTPases by p190 RhoGAP reduces human pancreatic cancer cell invasion and metastasis

Abstract

A number of small GTPases are involved in cancer cell proliferation, migration and invasion, acting as molecular switches that cycle between GTP‐ and GDP‐bound states. GTPase‐activating proteins (GAPs) have been established as a major class of negative regulators of Rho GTPase signaling. To investigate the biological function of p190 RhoGAP toward RhoA in cancer cell invasion and metastasis, we generated a chimera made of the RhoGAP domain of p190 and the C‐terminus of RhoA (p190‐RhoA chimera), and transfected it into human pancreatic cancer cells, AsPC‐1. Epidermal growth factor (EGF)‐induced activation of RhoA, as well as RhoB and RhoC, to a lesser extent, was significantly inhibited in p190‐RhoA chimera‐transfected AsPC‐1 cells compared with that of control cells (mock‐infected), when assessed by pull‐down assay for GTP‐bound RhoA, RhoB, and RhoC, respectively. EGF‐induced invasion of p190‐RhoA chimera transfectants was significantly inhibited compared with that of mock‐infected cells in a modified Boyden chamber assay. Furthermore, the mice injected intrasplenically with AsPC‐1 cells that overexpressed the p190‐RhoA chimera had a marked reduction in the number and size of metastatic nodules in the liver. These data suggest that the inhibitory action of p190 RhoGAP toward RhoA offers a novel approach to the treatment of invasion and metastasis of cancer cells. (Cancer Sci 2006; 97: 848–853)