Activation of Rho and Rho-Associated Kinase by GPR54 and KiSS1 Metastasis Suppressor Gene Product Induces Changes of Cell Morphology and Contributes to Apoptosis

Abstract

The mechanism of action of the metastasis suppressor KiSS1 and its receptor GPR54 is still incompletely characterized. Although the loss of KiSS1 expression by tumor cells has been associated with a metastatic phenotype, the nature of the cellular target of the secreted kisspeptins is unknown. Although an autocrine model of action has been generally assumed, metastasis suppression by KiSS1 has also been shown in cells that do not express GPR54, suggesting a paracrine mechanism in which kisspeptins affect cells in the metastatic niche. Activation of GPR54 was shown to inhibit cell motility and invasion of tumor cells, induce the formation of stress fibers, and reduce the expression of matrix metalloproteinase 9. We showed previously that the activation of GPR54 by kisspeptin-10 suppressed CXCR4-mediated chemotaxis in response to stromal cell-derived factor 1/CXCL12 and abolished the phosphorylation of Akt by CXCR4. We also demonstrated that activation of GPR54 inhibited Akt phosphorylation after the activation of epidermal growth factor receptor and the insulin receptor and triggered apoptosis in epithelial and lymphoid cell lines through a mechanism involving extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase. We show here that the activation of GPR54 induced immediate and profound changes of cell morphology, including cytoplasmic condensation and formation of unpolarized plasma membrane protrusions. These events were dependent on Rho and Rho-Associated Kinase (ROCK) activation. The activation of ROCK also contributed to GPR54-mediated apoptosis in 293 cells, and its effect was additive to and independent of ERK activation. These results suggest that RhoA and ROCK are additional key components of the antimetastatic effect of kisspeptins.KiSS1 was identified as a metastasis suppressor gene in human malignant melanoma cells (Welch et al., 1994;Lee et al., 1996). As opposed to tumor suppressors, metastasis suppressors do not inhibit the growth of primary tumors but specifically target the spread of tumor cells to distant organs and the establishment of secondary lesions. These metastasis suppressors can interfere with any step of the metastatic cascade, including invasion, angiogenesis, migration and homing, intravasation, survival, and proliferation in a new environment (Stafford et al., 2008). The metastatic phenotype may be conferred by the expression of a limited number of genes, including the chemokine receptor CXCR4, which has been shown to program organ-specific metastatic spread by multiple malignant tumor cell types (Kang et al., 2003;Minn et al., 2005). Other genes that contribute to the metastatic phenotype are involved in establishing a supportive microenvironment (Minn et al., 2005).KiSS1 was originally identified in experiments in which the transfer of human chromosome 6 to metastatic melanoma cells suppressed metastasis in a mouse xenograft model (Welch et al., 1994;Lee et al., 1996). The gene was identified by subtractive hybridization and differential display and w...

GPR54 Is a Target for Suppression of Metastasis in Endometrial Cancer

“…This was not observed when GPR54 was suppressed by siRNA treatment, again indicating that the effect of metastin is receptor dependent. These results are in agreement with the previously reported antimetastatic effects of metastin on intracellular signaling pathways (7,32). Thus far, little is known how GPR54 expression is regulated in cancer cells.…”

“…Metastin is a 54-amino acid splice variant of KISS1. Binding of metastin to GPR54 induces a series of intracellular signals such as activation of ERK and Rho or suppression of AKT, resulting in inhibition of chemotaxis and invasion (6,7). Expression of metastin or GPR54 has been associated with favorable prognosis in gastric, esophageal, pancreatic, thyroid, and bladder cancers.…”

Honokiol inhibits migration of renal cell carcinoma through activation of RhoA/ROCK/MLC signaling pathway

“…Cell migration is a key component of the tumor metastatic process (32). based on a number of studies, upregulated RhoA is associated with tumor progression in different types of cancer (33)(34)(35) and RhoA activation promotes the migration of cervical, colon and hepatocellular carcinoma (36)(37)(38).…”

International Union of Basic and Clinical Pharmacology. LXXVII. Kisspeptin Receptor Nomenclature, Distribution, and Function

“…Kisspeptin has been reported to induce apoptosis in cells, although there are conflicting reports about the role apoptosis may play in the metastasis-suppressing actions of kisspeptin (Harms et al, 2003;Becker et al, 2005). However, recent evidence favors an involvement of apoptosis (Navenot et al, 2009b), possibly by activation of Rho and Rho-associated kinase (Navenot et al, 2009a).…”