Role of isoprenylcysteine carboxylmethyltransferase-catalyzed methylation in Rho function and migration.
A number of proteins that play key roles in biological regulatory events undergo a process of post-translational modifications termed prenylation. The prenylation pathway consists of three enzymatic steps; the final processed protein is isoprenoid-modified and methylated on the C-terminal cysteine. This protein modification pathway plays a significant role in cancer biology because many oncogenic proteins undergo prenylation. Methylation of the C terminus by isoprenylcysteine carboxylmethyltransferase (Icmt) is the final step in the prenylation pathway. Cysmethynil, a specific Icmt inhibitor discovered in our laboratory, is able to inhibit Ras-mediated signaling, cell growth, and oncogenesis. We sought to examine the role of Icmt-mediated methylation on the behaviors of cancer cells associated with metastatic potential. Our results indicate that inhibition of methylation reduces migration of the highly metastatic MDA-MB-231 breast cancer cell line. In addition, cell adhesion and cell spreading are also significantly impacted by cysmethynil. To examine the mechanism of Icmt-dependent migration we focused on RhoA and Rac1, prenylated proteins that are important mediators of cell migration through their control of the actin cytoskeleton. Inhibition of Icmt significantly decreases the activation of both RhoA and Rac1; an increase in Rho GDP-dissociation inhibitor (RhoGDI) binding in the absence of methylation appears to contribute to this effect. Furthermore, in the absence of Icmt activity the addition of exogenous RhoA or Rac1 is able to partially rescue directed and random migration, respectively. These findings establish a role for Icmt-mediated methylation in cell migration and advance our understanding of the biological consequences of Rho methylation.
Cushman
Ian
I
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710; Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore 169857.
Casey
Patrick J
PJ
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710; Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore 169857. Electronic address: casey006@mc.duke.edu.
D000199:Actins / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D003599:Cytoskeleton / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use; D008745:Methylation; D011496:Protein Methyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
C569638:ARHGDIA protein, human; D000199:Actins; D020730:Guanine Nucleotide Dissociation Inhibitors; D007211:Indoles; D011993:Recombinant Fusion Proteins; C530692:cysmethynil; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D011496:Protein Methyltransferases; C056501:protein-S-isoprenylcysteine O-methyltransferase; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein