Identification of Ras farnesyltransferase inhibitors by microbial screening.

Abstract

A microbial screen using a yeast strain with conditional deficiency in the GPA1 gene was carried out to search for inhibitors of protein farnesyltransferase (PFT). A strain of Streptomyces was found to produce active compounds named UCF1-A, UCF1-B, and UCF1-C. Structural determination of these compounds revealed that UCF1-C is identical to the known antibiotic, manumycin, whereas UCF1-A and UCF1-B are structurally related to manumycin. All three UCF1 compounds suppress the lethality of gpa1 disruption, with UCF1-C exhibiting the strongest activity. UCF1 inhibits yeast as well as rat brain PFT. Fifty percent inhibition of yeast PFT activity is observed with 5 microM UCF1-C. Kinetic analyses of the inhibition suggest that UCF1-C acts as a competitive inhibitor of PFT with respect to farnesyl pyrophosphate, exhibiting a Ki of 1.2 microM, whereas the same compound appears to act as a noncompetitive inhibitor of PFT with respect to the farnesyl acceptor, the Ras protein. UCF1-C shows significant activity to inhibit the growth of Ki-ras-transformed fibrosarcoma, raising the possibility of its use as an antitumor drug.

Reactive oxygen species‐dependent destruction of MEK and Akt in Manumycin stimulated death of lymphoid tumor and myeloma cell lines

“…10 Dysfunctional Ras is found in 30% of all known human cancers, including lymphomas and prostate cancers, 3 and moreover, constitutively active Ras is found in >90% of pancreatic cancers and in 20-30% of multiple myeloma isolates. 3,15 Therefore, compounds such as Man-A were especially prospected for their potential use as first lines of defense against tumors harboring constitutively active Ras.…”

“…One such agent is Manumycin-A (Man-A), a natural isolate from Streptomyces parvulus broth, which was identified as a competitive inhibitor of the farnesyl donor, farnesylpyrophosphate. 10 Based on this activity, Man-A and compounds with similar activities have been extensively employed to probe the roles of Ras prenylation and of Ras activity in cellular and tumor biology.…”

Contribution of Src and Ras pathways in FGF-2 induced endothelial cell differentiation

“…To determine if FGFR-1 signaling in cells cultured on ®bronectin or collagen was dependent on monomeric GTP-binding proteins, we utilized two di erent inhibitors; the farnesylation inhibitor manumycin (Hara et al, 1993) and the Ras-dislodging antagonist FTS (Haklai et al, 1998). These inhibitors are known to a ect Ras function since membrane association is a prerequisite for Ras activity (Howe et al, 1992;Leevers and Marshall, 1992); the e ect of manumycin on geranylgeranylated Ras-like proteins such as Rac and RhoA and C remain to be determined (Cox and Der, 1997).…”

“…On the next day, medium was changed to Ham's F12 medium containing 2% FBS with either vehicle (DMSO) or inhibitor (Ras inhibitors manumycin (a kind gift of Dr Mitsunobu Hara, Tokyo Research Laboratory, Kyowa Hakko Kogyo Co. Ltd, Tokyo, Japan; ®nal concentration 1 mM) (Hara et al, 1993) or S-trans, trans-farnesylthiosalicylic acid (FTS; 50 mM ®nal concentration) (Haklai et al, 1998). Twenty minutes later, 1 ng/ml FGF-2 was added as indicated and the culture was continued for 3 days.…”

Inhibition of farnesyltransferase: A rational approach to treat cancer?

“…FTase inhibitors have also demonstrated antitumor efficacy in mice [60,44,68,77]. Initial studies utilized nude mice so that xenograft tumors could be produced using transformed rodent fibroblasts that were characterized for their sensitivity to FTase inhibitors in cell culture.…”