Prenyl transferase inhibitors

Details Prenyl transferase inhibitors Prenyl transferase inhibitors

1999-06-16

2003-07-01

Solola, Taofiq (Department: 1626)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Having -c-, wherein x is chalcogen, bonded directly to...

C514S461000, C549S079000, C549S497000, C558S152000, C568S715000

Reexamination Certificate

active

06586461

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to novel analogs of farnesol and geranylgeraniol, and more specifically to 3-substituted farnesol and geranylgeraniol analogs, that block the prenylation of proteins in cells.
2. Background of the Prior Art
Proteins are modified by a mevalonate pathway intermediate. There are three different protein prenylation motifs in this pathway—farnesylation, geranylgeranylation, and bis-geranylgeranylation. The first modification is carried out by an enzyme, protein farnesyl transferase (FTase), which recognizes the CAAX box (where A=aliphatic amino acid and X=Ser or Met) at the carboxyl terminus of the protein substrate and then attaches the farnesyl group from farnesyl diphosphate (FPP) to the free sulfhydryl of the cysteine residue.
FIG. 1
is a reaction pathway for protein farnesylation of, illustratively, a Ras protein. The second, closely related enzyme, protein geranylgeranyltransferase I (GGTase I), attaches a geranylgeranyl moiety from geranylgeranyl diphosphate (GGPP) to a cysteine in a similar CAAX box, where leucine (X=Leu) is the carboxyl terminal residue. The third enzyme, GGTase II, attaches two geranylgeranyl residues to two cysteine residues at the carboxyl terminus of Rab proteins.
Once initial studies demonstrated that the key signal transduction protein and oncogene product Ras is farnesylated, FTase became the subject of intense research interest on the basis that inhibitors of this enzyme could block the action of mutant Ras proteins and halt the growth of ras-transformed cells, and therefore would be potential anti-cancer agents. Mutant forms of Ras proteins are involved in about 30% of human cancers. These include pancreatic adenocarcinomas, colon adenocarcinomas, and adenomas; thyroid carcinomas and adenomas; lung adenocarcinomas; myeloid leukemia; and melanomas. Therefore, there is a need in the art for an FTase inhibitor that can block the growth of ras-transformed cells in vivo.
Significant progress has been made in the development of peptide-based FTase inhibitors, and some of these compounds have shown great promise in vivo as potential anti-cancer agents. Merck has reported a peptidomimetic inhibitor that is effective in vivo in a mouse pancreatic carcinoma model. However, the peptide-based inhibitors are complicated molecules that require numerous synthetic steps to prepare. This limits their availability and increases cost. Moreover, the peptidomimetic inhibitors are not able to penetrate cell membranes due to their polarity. Therefore, in order to be administered in vivo, these drugs must be converted to a prodrug ester form. Even in the prodrug form, the in situ (cell culture) and in vivo potency is several orders of magnitude less than the potency of the parent inhibitor and the isolated enzyme. Furthermore, since peptide-based drugs are usually polar, they are susceptible to proteolytic degradation. This prevents the compound, even in its prodrug form, from being given orally, thereby necessitating dosing by i.v. administration.
While the specificity of FTase for its protein substrate has been extensively explored, there have only been limited reports on its specificity for farnesyl pyrophosphate or farnesyl diphosphate (FPP; Compound 10 on FIG.
1
). FPP is a biosynthetic intermediate that occupies a key branch point in the mevalonate pathway. The primary route for FPP metabolism is its conversion into squalene by the enzyme squalene synthase. Squalene is then transformed by a series of enzymatic steps to cholesterol. Squalene synthase has attracted significant interest as a potential additional target for cholesterol-lowering agents. FPP is also converted in the cell to other important isoprenoids, such as dolichol and ubiquinone, which are utilized in protein glycosylation and electron transport, respectively. Most recently it has been recognized that FPP plays an additional crucial role in the cell. It is utilized by the enzyme protein farnesyl transferase (FTase) as the source of a farnesyl moiety that is attached to the cysteine sulfhydryl on the ras G proteins and certain other proteins which bear a carboxyl-terminal Cys—AAX—OH sequence. This farnesylation event and the subsequent proteolysis and carboxymethylation modifications serve to increase the hydrophobicity of these proteins, and thus, convert them to peripheral membrane proteins. There is, therefore, a need for FPP-based FTase inhibitors as probes for analyzing the FPP-binding site of FTase.
Novel FPP analogs were synthesized as probes of the FPP-binding site of FTase and characterized by their interaction with recombinant yeast FTase (yFTase). The vinyl analog, 3-vinyl farnesyl diphosphate (3-vFPP;
FIG. 1
, Compound 10a) was designed as a potential mechanism-based inhibitor, but instead was a poor alternative substrate for yFTase . These results were reported in Gibbs, et al.,
J. Org. Chem
., Vol. 60, pages 7821-7829 (1995). In contrast, a sterically encumbered analog, 3-tert-butyl farnesyl diphosphate (3-tbFPP;
FIG. 1
, Compound 10b), is an exceptionally poor substrate and a potent competitive inhibitor of this enzyme. See, Mu, et al.,
J. Org. Chem
., Vol. 61, pages 801-8015 (1996).
The results obtained by the various prenyl transferase inhibitors proposed in the art demonstrate unpredictability with respect to inhibition of FTase or geranylgeranylase (GGTase) in vitro and in vivo. There is, thus, a need for prenyl transferase inhibitors that are effective against mammalian FTase, which is the clinically relevant variant of the enzyme, both in vitro for research purposes and in vivo for therapeutic purposes.
It is, therefore, an object of this invention to provide novel prenyl transferase inhibitors that are easier to prepare than other farnesyl analog FTase inhibitors.
It is also an object of this invention to provide novel prenyl transferase inhibitors that exhibit better cellular penetration.
It is another object of this invention to provide novel prenyl transferase inhibitors that are useful as anticancer agents.
It is a still further object of this invention to provide novel prenyl transferase inhibitors that are bioavailable and non-toxic to the host and that are cytotoxic as compared to other FTase inhibitors that are merely cytostatic.
It is yet another object of this invention to provide novel geranylgeranyl transferase inhibitors that are potentially useful as restenosis inhibitors.
SUMMARY OF THE INVENTION
The foregoing and other objects are achieved by this invention which comprises, in a composition of matter embodiment, 3-substituted isoprenol analogs that block the prenylation of proteins in cells. In preferred embodiments, the isoprenol analogs are analogs of the alcohols, farnesol and geranylgeraniol, as well as their diphosphate derivatives. The active, diphosphate derivatives of these compounds are potent inhibitors of mammalian protein prenyltransferases. The alcohol precursors efficiently block the growth of anchorage-independent ras-transformed cells.
The farnesol and geranylgeraniol analogs within the contemplation of this invention, include without limitation,
Formula (I):
wherein R′ is a C
10
-C
20
saturated or unsaturated alkyl, aryl, heteroaryl, or cycloalkyl which, in some embodiments, include substituents, some of which may contain heteroatoms, such as N, O, S, and F; R is a C
2
-C
10
saturated or unsaturated alkyl, aryl, cycloalkyl, or C
6
-C
10
aromatic or heteroaromatic group which may be substituted; and X is —OH or —P
2
O
7
. As used herein, the composition includes enantiomers, stereoisomers, and geometric isomers.
In preferred embodiments, R′ is geranyl and farnesyl and R is selected from the group vinyl, ethyl, allyl, saturated and unsaturated isomers of propyl, butyl, and pentyl, cyclopropyl, isobutyl, cyclopentyl, phenyl and heterosubstituted moieties, such as fluorophenyl, (trimethylsilyl)methyl, 1-ethoxyvinyl, and 2-furanyl, 2-thiophenyl.
In a preferred embodiment, the 3-substituted farnesol or geranylgeraniol anal

Affiliated with

Also associated with

Rating

Prenyl transferase inhibitors does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Prenyl transferase inhibitors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Prenyl transferase inhibitors will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3069547