ROCK1 and ROCK2 Are Required for Non-Small Cell Lung Cancer Anchorage-Independent Growth and Invasion

Abstract

Evidence is emerging that the closely related ROCK1 and ROCK2 serine/threonine kinases support the invasive and metastatic growth of a spectrum of human cancer types. Therefore, inhibitors of ROCK are under preclinical development. However, a key step in their development involves the identification of genetic biomarkers that will predict ROCK inhibitor anti-tumor activity. One identified mechanism for ROCK activation in cancer involves the loss of function of the DLC1 tumor suppressor gene, which encodes a GTPase activating protein (RhoGAP) for the RhoA and RhoC small GTPases. DLC-1 loss may lead to hyperactivation of RhoA/C and its downstream effectors, the ROCK kinases. We therefore determined whether loss of DLC-1 protein expression identifies non-small cell lung carcinoma (NSCLC) cell lines whose growth and invasion phenotypes are sensitive to ROCK inhibition. We identified and characterized a novel small molecule pharmacologic inhibitor of ROCK and additionally applied genetic approaches to impair ROCK1 and/or ROCK2 activity, and we determined that although NSCLC anchorage-dependent growth was ROCK-independent, both anchorage-independent growth and Matrigel invasion were ROCK-dependent. However, loss of DLC-1 expression did not correlate with ROCK activation or with OXA-06 sensitivity. Unexpectedly, suppression of ROCK1 or ROCK2 expression alone was sufficient to impair anchorage-independent growth, supporting their non-overlapping roles in oncogenesis. Mechanistically, the block in anchorage-independent growth was associated with accumulation of cells in the G0/G1 phase of the cell cycle, but not increased anoikis. We conclude that ROCK may be a useful therapeutic target for NSCLC.

Gα13/PDZ-RhoGEF/RhoA Signaling Is Essential for Gastrin-Releasing Peptide Receptor–Mediated Colon Cancer Cell Migration

“…Increased RhoA activation and signaling through its downstream effectors, such as Rho-associated kinase (ROCK), contributes to cancer progression. Activation of the RhoA-ROCK signaling axis initiates cytoskeletal changes that are essential for cancer cell motility and invasion, initiates gene transcription, and promotes cancer cell proliferation (Yagi et al, 2011;Vigil et al, 2012;Zhang et al, 2013). It is currently unknown if GRPR-mediated RhoA-ROCK signaling plays a role in regulation of colon cancer cell migration.…”

MicroRNA-144 acts as a tumor suppressor by targeting Rho-associated coiled-coil containing protein kinase 1 in osteosarcoma cells

“…It has been well established that ROCK1 is involved in the reorganization of the actin cytoskeleton, which is important in cell migration and invasion (17)(18)(19). In addition, the expression levels of ROCK1 were reported to be significantly upregulated in multiple types of human cancer, including bladder (14), prostate (20) and lung (21) cancer, suggesting that ROCK1 acts as an important oncogene in multiple types of cancer. A previous study investigated the role of ROCK1 in osteosarcoma.…”

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).…”