Development of Highly Potent Inhibitors of Ras Farnesyltransferase Possessing Cellular andin VivoActivity

Abstract

Analogs of CVFM (a known nonsubstrate farnesyltransferase (FT) inhibitor derived from a CA1A2X sequence where C is cysteine, A is an aliphatic residue, and X is any residue) were prepared where phenylalanine was replaced by (Z)-dehydrophenylalanine, 2-aminoindan-2-carboxylate, 1,2,3,4-tetrahydroisoquinoline-3-carboxylate (Tic), and indoline-2-carboxylate. The greatest improvement in FT inhibitory potency was observed for the Tic derivative (IC50 = 1 nM); however, this compound was ineffective in blocking oncogenic Ras-induced transformation of NIH-3T3 fibroblast cells. A compound was prepared in which both the Cys-Val methyleneamine isostere and the Tic replacement were incorporated. This derivative inhibited FT with an IC50 of 0.6 nM and inhibited anchorage-independent growth of stably transformed NIH-3T3 fibroblast cells by 50% at 5 microM. Replacing the A1 side chain of this derivative with a tert-butyl group and replacing the X position with glutamine led to a derivative with an IC50 of 2.8 nM and an EC50 of 0.19 microM, a 26-fold improvement over (S*,R*)-N-[[2-[N-(2-amino-3-mercaptopropyl)-L-valyl]-1,2,3,4- tetrahydro-3-isoquinolinyl]carbonyl]-L-methionine. This derivative, (S*,R*)-N-[[2-[N-(2-amino-3-mercaptopropyl)-L-tert-leucyl]-1,2,3,4 - tetrahydro-3-isoquinolinyl]-carbonyl]-L-glutamine, was evaluated in vivo along with (S*,R*)-N-[[2-[N-(2-amino-3- mercaptopropyl)-L-tert-leucyl]-1,2,3,4-tetrahydro-3- isoquinolinyl]carbonyl]-L-methionine methyl ester for antitumor activity in an athymic mouse model implanted ip with H-ras-transformed rat-1 tumor cells. When administered by injection twice a day at 45 mg/kg for 11 consecutive days, both compounds showed prolonged survival time (T/C = 142-145%), thus demonstrating efficacy against ras oncogene-containing tumors in vivo.

Geranylgeranyltransferase I Inhibitors Target RalB To Inhibit Anchorage-Dependent Growth and Induce Apoptosis and RalA To Inhibit Anchorage-Independent Growth

“…The fact that prenylation is required for the oncogenic activity of small GTPases prompted us and others to design FTase and GGTase I inhibitors (FTIs and GGTIs) as potential anticancer drugs (14,26,35,57). While numerous studies have shown that FTIs suppress oncogenic and tumor survival pathways, the actual mechanism by which FTIs inhibit tumor growth is not known (34,44).…”

Farnesyltransferase inhibitors: recent advances

“…BMS initiated their pursuit of protein competitive FTIs with peptidomimetics of the CAAX box [44][45][46] and claimed their first non-peptide class of FTIs, including BMS-214662, in 1997 [132]. A related class containing 1,2,5-benzothiadiazepine-1, 1-dioxides with N-2 imidazolylalkyl substituents [133] was reported in 2000.…”

Assessment of the Bioactive Conformation of the Farnesyltransferase Protein Binding Recognition Motif by Computational Methods

“…More extensive structure-activity studies showed the analog Cys-Val-Phe-Met to be the most potent inhibitor among 42 CXXX analogs, where X stands for all the possible natural amino acids (17). Subsequent reduction of selected amide bonds in CA 1 A 2 X-based inhibitors Jed to a significant improvement of the inhibitory potency and activity in whole cells (18). Similarly, analogs containing confonnationally constrained amino acid residues were also shown to be potent inhibitors (19).…”

“…Accordingly, the conformational profiles of a small set of CA 1 A 2 X-based inhibitors (18), with A 2 being an confonnationally constrained aromatic amino acid residue, were compared in order to assess the conformational requirements of the Ff inhibitors. Specifically, two active and two inactive inhibitors were selected for the present study: the active analogs Cys-Val-Tic-Met (1) and Cys-Val-'¥(CH 2 NH)TicMet (2) and the inactive analogs Cys-Val-Tic-'¥(CH 2 NH)Met (3) and Cys-Val-AicMet (4), where Tic and Aic are the unnatural amino acid residues (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate and 2-aminoindane-2-carboxylic acid, respectively.…”

“…Specifically, two active and two inactive inhibitors were selected for the present study: the active analogs Cys-Val-Tic-Met (1) and Cys-Val-'¥(CH 2 NH)TicMet (2) and the inactive analogs Cys-Val-Tic-'¥(CH 2 NH)Met (3) and Cys-Val-AicMet (4), where Tic and Aic are the unnatural amino acid residues (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylate and 2-aminoindane-2-carboxylic acid, respectively. The in vitro FT inhibitory activity of the four peptide analogs selected for the present study are listed in Table I ( 18).…”