The Sprouty-related protein, Spred, inhibits cell motility, metastasis, and Rho-mediated actin reorganization

Abstract

Sprouty and the Sprouty-related protein, Spred (Sprouty-related Ena/vasodilator-stimulated phosphoprotein homology-1 (EVH1) domain-containing protein), inhibit Ras-dependent extracellular signal-regulated kinase (ERK) signaling induced by a variety of growth factors. Since Sprouty proteins have been shown to inhibit not only ERK activation but also cell migration, we postulated that Spreds also inhibit cellular migration. Using stably highly metastatic LM8 cells infected with the Spred1-Sendai virus vector, we demonstrated that Spred1 inhibits the metastasis of LM8 cells in nude mice. Spred1 overexpression also inhibited migration of cells in vitro in response to chemokines, CCL19 and CCL21. We also found that Spred1 overexpression dissolved actin-stress fibers. Both EVH1 domain and C-terminal Sprouty-related domain were required for actin reassembly. Spred1 and Spred2 suppressed constitutively activated RhoA (V14RhoA)-induced stress fiber formation and serum response factor activation. Spred1 bound to activated RhoA, but not cdc42 and Rac. Spred1 also inhibited chemokine-induced RhoA activation and active RhoA-induced Rho-kinase activation. These data suggest that Spreds are key regulators of RhoA-mediated cell motility and signal transduction. Furthermore, our study suggests that the induction of Spreds could be a novel strategy for preventing cancer cell metastasis.

Spreds, inhibitors of the Ras/ERK signal transduction, are dysregulated in human hepatocellular carcinoma and linked to the malignant phenotype of tumors

“…More recently, we showed that Spred-1 prevents murine osteosarcoma cell proliferation and metastasis through inhibition of the Ras/Raf-1/ERK pathway (Miyoshi et al, 2004). However, the relationship between Spred and human cancer remained to be investigated.…”

MAP kinase signalling pathways in cancer

“…For example, activated NRas induces the cytoplasmic mislocalization of p27 via the Ral-GEF pathway, leading to the disruption of TGFb-mediated Smad nuclear translocation Accumulating evidence also suggest that the expression of different feedback inhibitors the ERK pathway is deregulated in cancer (Figure 3). These include MAP kinase phophatases (MKPs) and Sprouty family members (Miyoshi et al, 2004;Tsavachidou et al, 2004;Bloethner et al, 2005;Tsujita et al, 2005;Fong et al, 2006). Interestingly, ERK signalling is restrained even in transformed cells through multiple negative feedback loops.…”

Gene Disruption of Spred-2 Causes Dwarfism

“…Spred-2 Knock-out Mice-Spred-1 overexpression in osteosarcoma cells inhibited tumor proliferation, metastasis, cell migration, and Rho-dependent actin-stress fiber remodeling (40). Therefore, one could speculate about a phenotype with hyperproliferative cell populations in different organs and tumor development with a forced metastatic situation in Spred-2-deficient mice.…”

“…Spred-1 binds to activated RhoA and inhibits chemokineinduced RhoA activation and active RhoA-induced Rho kinase activation. By this mechanism, Spred inhibits cell motility, metastasis, and Rho-mediated actin reorganization (40). Recently, it has been demonstrated that Spred-1 is also highly expressed in hematopoietic cells and negatively regulates stem cell factor-and interleukin 3-mediated ERK/MAP kinase activation.…”