Abstract

Lysophosphatidic acid (LPA) is a biolipid that has diverse biological activities implicated in ovarian cancer initiation and progression. Previous studies have shown the critical role of the Rho/Rho-associated kinase (ROCK) pathway in LPA-induced ovarian cancer progression. However, detailed underlying mechanism by which the Rho/ROCK pathway induces ovarian cancer cell invasion is still incompletely understood. In the present study, we observed that the Rho/ROCK pathway is implicated in the production of proteolytic enzymes, leading to LPA-induced ovarian cancer cell invasion. LPA induced matrix metalloproteinase (MMP)-9 expression in CAOV-3 and PA-1 cells and urokinase-type plasminogen activator (uPA) expression in SKOV-3 cells. LPA-induced proteolytic enzyme expression was required for the invasion of ovarian cancer cells expressing corresponding enzymes. Pretreatment of cells with a pharmacological inhibitor of Rho/ROCK (Y-27632) or overexpression of a dominant-negative mutant of Rho (Rho N19) profoundly inhibited LPA-induced proteolytic enzyme expression as well as the invasive potential of ovarian cancer cells. In addition, transfection with dominant-negative Ras (Ras N17) significantly inhibited LPA-induced Rho activation as well as MMP-9 and uPA expression. Consistently, Y-27632 reduced LPA-induced nuclear factor (NF)-κB activation that is critical for proteolytic enzyme expression and cellular invasion. Collectively, we demonstrate a mechanism by which LPA promotes ovarian cancer progression through coordinate activation of a Ras/Rho/ROCK/NF-κB signaling pathway and the proteolytic enzyme secretion, providing novel biomarkers and promising therapeutic targets for ovarian cancer cell progression.Oncogene advance online publication, 16 January 2012; doi:10.1038/onc.2011.595.