RhoC (Ras homolog gene family, member C) is a small (~21 kDa) signaling G protein (more specifically a GTPase), and is a member of the Rac subfamily of the family Rho family of GTPases.[5] It is encoded by the gene RHOC.[6]
It is prenylated at its C-terminus, and localizes to the cytoplasm and plasma membrane. It is thought to be important in cell locomotion. It cycles between inactive GDP-bound and active GTP-bound states and function as molecular switches in signal transduction cascades.
Rho proteins promote reorganization of the actin cytoskeleton and regulate cell shape and motility. RhoC can activate formins such as mDia1 and FMNL2 to remodel the cytoskeleton.[7][8][9]
Overexpression of RhoC is associated with cell proliferation and causing tumors to become malignant.[10] It causes degradation and reconstruction of the Extracellular Matrix (ECM) which helps cells escape the tissue they are currently in. It enhances cell motility giving it the ability to become invasive.[11] It has been found to have a direct relationship to advanced tumor stage and metastasis, with increases in stage being related to increases in RhoC expression.[12] RhoC-deficient mice can still develop tumors but these fail to metastasize, arguing that RhoC is essential for metastasis.[13]
It has also been found to enhance the creation of angiogenic factors such as VEGF, which is necessary for a tumor to become malignant.[12][14]
In a study by Vega,[15] RhoC was knocked out which resulted in cells spreading out wide in all directions. When RhoC was disabled, the cell's abilities to move in a specific direction and migrate was impaired. It also reduced the cell's speed of movement, because it was difficult, and sometimes impossible, to polarize the cell.
RhoC expression has been associated with several signaling pathways and effectors. Here is a list of the ones found so far:
IQGAP1 (IQ-domain GTP-ase Activating Protein): an effector of RhoC to enhance expression of cyclin E and cyclin D1. This resulted in cells being promoted to enter S phase more rapidly [16]
RhoC small interfering RNA (siRNA) have been used in studies to successfully inhibit proliferation of some invasive cancers [16][23]
RhoC can be used as a biomarker for judging the metastatic potential of tumors[21][24]
One study used "recombinant adenovirus mediated RhoC shRNA in tandem linked expression" to successfully inhibit RhoC [23]
It has been found that RhoC expression is not important for embryogenesis but it is only important for metastasis, which would make it a good target for treatments.[14]
A RhoC targeted therapy (RV001 by RhoVac) is currently tested in prostate cancer in an ongoing clinical phase 2b program in the US and Europe. Results are expected mid 2022 (Reference: https://clinicaltrials.gov/ct2/show/NCT04114825)
^ abcdefghZhao Y, Zhi-hong Z, Hui-mian X (2010). "RhoC Expression Level Is Correlated with the Clinicopathological Characteristics of Ovarian Cancer and the Expression Levels of ROCK-I, VEGF, and MMP9". Gynecologic Oncology. 116 (3): 563–71. doi:10.1016/j.ygyno.2009.11.015. PMID20022093.
^Genda T, Sakamoto M, Ichida T, Asakura H, Kojiro M, Narumiya S, Hirohashi S (1999). "Cell Motility Mediated by Rho and Rho-Associated Protein Kinase Plays a Critical Role in Intrahepatic Metastasis of Human Hepatocellular Carcinoma". Hepatology. 30 (4): 1027–36. doi:10.1002/hep.510300420. PMID10498656. S2CID35864555.
^ abVan Golen KL, Bao LW, Pan Q, Miller FR, Wu ZF, Merajver SD (2002). "Mitogen Activated Protein Kinase Pathway Is Involved in RhoC GTPase Induced Motility, Invasion and Angiogenesis in Inflammatory Breast Cancer". Clinical & Experimental Metastasis. 19 (4): 301–11. doi:10.1023/A:1015518114931. hdl:2027.42/42584. PMID12090470. S2CID211284.
^ abKleer CG, Griffith KA, Sabel MS, Gallagher G, van Golen KL, Wu ZF, Merajver SD (2005). "RhoC-GTPase Is a Novel Tissue Biomarker Associated with Biologically Aggressive Carcinomas of the Breast". Breast Cancer Research and Treatment. 93 (2): 101–10. doi:10.1007/s10549-005-4170-6. hdl:2027.42/44231. PMID16187229. S2CID9215922.
^Wang W, Wu F, Fang F, Tao Y, Yang L (2008). "RhoC Is Essential for Angiogenesis Induced by Hepatocellular Carcinoma Cells via Regulation of Endothelial Cell Organization". Cancer Science. 99 (10): 2012–18. doi:10.1111/j.1349-7006.2008.00902.x. PMID19016761. S2CID23715139.
Maekawa M, Ishizaki T, Boku S, et al. (1999). "Signaling from Rho to the actin cytoskeleton through protein kinases ROCK and LIM-kinase". Science. 285 (5429): 895–8. doi:10.1126/science.285.5429.895. PMID10436159.
Shao F, Dixon JE (2004). "YopT is a Cysteine Protease Cleaving Rho Family GTPases". The Genus Yersinia. Advances in Experimental Medicine and Biology. Vol. 529. pp. 79–84. doi:10.1007/0-306-48416-1_14. ISBN 0-306-47759-9. PMID12756732.
Laudanna C (2008). "RhoC". AfCS-Nature Molecule Pages. doi:10.1038/mp.a002065.01 (inactive 2024-04-13).{{cite journal}}: CS1 maint: DOI inactive as of April 2024 (link)