Identification of novel ROCK inhibitors with anti-migratory and anti-invasive activities

Abstract

ROCK1 and ROCK2 mediate important processes such as cell migration, invasion and metastasis; making them good targets for the development of antitumor agents. Recently, using a fragment-based approach and X-ray crystallography, we reported on the design and synthesis of novel Rho-kinase inhibitors (RKIs). Here, we selected a pair of RKIs, the closely-related structural analogues RKI-18 (potent; IC50 values of 397 nM (ROCK1) and 349 nM (ROCK2)) and RKI-11 (weak/inactive; IC50 values of 38 µM (ROCK1) and 45 µM (ROCK2), as chemical probes and determined their effects on cytoskeleton organization, signaling, apoptosis, anchorage-dependent and –independent growth, migration and invasion. RKI-18 but not RKI-11 suppresses potently the phosphorylation of the ROCK substrate MLC2 in intact human breast, lung, colon and prostate cancer cells. Furthermore, RKI-18 is highly selective at decreasing the levels of P-MLC2 over those of P-Akt, P-S6 and P-Erk ½. RKI-18 suppresses ROCK-mediated actin fiber formation following stimulation with LPA as well as PAK-mediated lamelipodia and filopodia formation following bradykinin or PDGF stimulation. Furthermore, RKI-18 but not RKI-11 inhibits migration, invasion and anchorage-independent growth of human breast cancer cells. The fact that the active ROCK inhibitor RKI-18 but not the inactive closely related structural analogue RKI-11 is effective at suppressing malignant transformation suggests that inhibition of ROCK with RKI-18 results in preventing migration, invasion and anchorage-independent growth. The potential of this class of RKIs as anti tumor agents warrants further advanced preclinical studies.

Molecular Pathways: Targeting the Kinase Effectors of RHO-Family GTPases

“…Fasudil has been shown to inhibit tumor progression in vivo ; moreover, this inhibitor has been tested extensively in humans for the treatment of cerebral vasospasm. The recently discovered ROCKI/II inhibitors, RKI-18 and RKI-1447 have been shown to prevent migration, invasion and anchorage-independent growth of human breast cancer cells (61, 62). Further, RKI-1447 also demonstrated antitumor activities in transgenic mouse model of breast cancer, reducing mammary tumor growth by 87% (61).…”

Rho Kinases in Health and Disease: From Basic Science to Translational Research

“…Several studies described the inhibitory effects of ROCK blockers on in vitro adherent tumor cell migration and invasion (Gutjahr et al, 2005;Torka et al, 2006;Patel et al, 2014), although recent data showed that ROCK inhibition increases the metastatic potential of nonadherent breast tumor cells by increasing their reattachment efficacy (Bhandary et al, 2015). ROCKs have been implicated in the pathogenesis of cancer and several aspects of human tumor progression (Rath and Olson, 2012).…”

Rho Kinase Inhibitors Block Melanoma Cell Migration and Inhibit Metastasis

“…Consequently, they fail to block cell migration completely. Recent studies reported the development of several new ROCK inhibitors, including, OXA-06 and RKI-18, which showed good potency against ROCK in vitro and in cells (14,15). However, the OXA-06 compound has poor pharmacokinetic properties for use in vivo (14) and no in vivo data for RKI-18 were reported (15).…”