Identification and characterization of mechanism of action of P61-E7, a novel phosphine catalysis-based inhibitor of geranylgeranyltransferase-I.
Small molecule inhibitors of protein geranylgeranyltransferase-I (GGTase-I) provide a promising type of anticancer drugs. Here, we first report the identification of a novel tetrahydropyridine scaffold compound, P61-E7, and define effects of this compound on pancreatic cancer cells. P61-E7 was identified from a library of allenoate-derived compounds made through phosphine-catalyzed annulation reactions. P61-E7 inhibits protein geranylgeranylation and blocks membrane association of geranylgeranylated proteins. P61-E7 is effective at inhibiting both cell proliferation and cell cycle progression, and it induces high p21(CIP1/WAF1) level in human cancer cells. P61-E7 also increases p27(Kip1) protein level and inhibits phosphorylation of p27(Kip1) on Thr187. We also report that P61-E7 treatment of Panc-1 cells causes cell rounding, disrupts actin cytoskeleton organization, abolishes focal adhesion assembly and inhibits anchorage independent growth. Because the cellular effects observed pointed to the involvement of RhoA, a geranylgeranylated small GTPase protein shown to influence a number of cellular processes including actin stress fiber organization, cell adhesion and cell proliferation, we have evaluated the significance of the inhibition of RhoA geranylgeranylation on the cellular effects of inhibitors of GGTase-I (GGTIs). Stable expression of farnesylated RhoA mutant (RhoA-F) results in partial resistance to the anti-proliferative effect of P61-E7 and prevents induction of p21(CIP1/WAF1) and p27(Kip1) by P61-E7 in Panc-1 cells. Moreover, stable expression of RhoA-F rescues Panc-1 cells from cell rounding and inhibition of focal adhesion formation caused by P61-E7. Taken together, these findings suggest that P61-E7 is a promising GGTI compound and that RhoA is an important target of P61-E7 in Panc-1 pancreatic cancer cells.
Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California, United States of America.
Lai N
LN
Chan
Hannah D G
HD
Fiji
Masaru
M
Watanabe
Ohyun
O
Kwon
Fuyuhiko
F
Tamanoi
D000199:Actins / Q000378:metabolism; D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D002384:Catalysis; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D055808:Drug Discovery / Q000379:methods*; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D019169:Jurkat Cells; D007930:Leucine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D041681:NIH 3T3 Cells; D010720:Phosphines / Q000737:chemistry*; D017368:Protein Prenylation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D011758:Pyrroles / Q000737:chemistry; D013449:Sulfonamides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D000199:Actins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; C570200:P61-E7 compound; D010720:Phosphines; D011725:Pyridines; D011758:Pyrroles; D013449:Sulfonamides; D019883:Alkyl and Aryl Transferases; C083291:geranylgeranyltransferase type-I; D020742:rhoA GTP-Binding Protein; C044646:phosphine; D007930:Leucine