Growth inhibition by the farnesyltransferase inhibitor FTI-277 involves Bcl-2 expression and defective association with Raf-1 in liver cancer cell lines.
Farnesyltransferase inhibitors (FTIs) block the growth of tumor cells in vitro and in vivo with minimal toxicity toward normal cells. In general, inhibition of protein farnesylation results in G0/G1 cell cycle block, G2/M cell cycle arrest, or has no effect on cell cycle progression. One aspect of FTI biology that is poorly understood is the ability of these drugs to induce cancer cell growth arrest at the G2/M phase of cell cycle. In the present study, we investigated the effects of the farnesyltransferase inhibitor FTI-277 on two human liver cancer cell lines, HepG2 and Huh7. Treatment of these cells with FTI-277 inhibited Ras farnesylation in a dose-dependent manner. Both HepG2 and Huh7 cell growth was inhibited by FTI-277 and cells accumulated at the G2/M phase of the cell cycle. In HepG2 and Huh7 cells, FTI-277 induced an up-regulation of the cyclin-dependent kinase inhibitor p27(Kip1) without affecting the cellular levels of p53 and p21(Waf1). This event correlated with reduced activity of the cyclin-dependent kinase 2 and cyclin-dependent kinase 1. Moreover, increased expression of Bcl-2 protein was observed in HepG2 and Huh7 cells treated with FTI-277, and this was coincidental with reduced association between Raf-1 and Bcl-2. Finally, transient transfection of a dominant-negative Ras allele induced Bcl-2 expression and reduced Bcl-2/Raf-1 association demonstrating a requirement for Ras. Taken together, these findings show that increased expression of p27(Kip1) and Bcl-2 is concomitant with altered association between Ras, Raf-1 and Bcl-2 and suggest that this is responsible for the growth-inhibitory properties of FTI-277.
Mazzocca
Antonio
A
Dipartimento di Medicina Interna, Università di Firenze, Firenze, Italy.
Giusti
Sabrina
S
Hamilton
Andrew D
AD
Sebti
Said M
SM
Pantaleo
Pietro
P
Carloni
Vinicio
V
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors*; D042846:CDC2-CDC28 Kinases; D017489:CDC28 Protein Kinase, S cerevisiae / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D051231:Farnesyltranstransferase; D016195:G2 Phase / Q000187:drug effects; D015870:Gene Expression; D006801:Humans; D008715:Methionine / Q000031:analogs & derivatives* / Q000187:drug effects*; D008938:Mitosis / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; C096856:FTI 277; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D008715:Methionine; D019883:Alkyl and Aryl Transferases; D051231:Farnesyltranstransferase; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D042846:CDC2-CDC28 Kinases; D017489:CDC28 Protein Kinase, S cerevisiae; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins