Inhibition of cell growth of human hepatoma cell line (HepG2) by a farnesyl protein transferase inhibitor: A preferential suppression of ras farnesylation

Abstract

So far, treatment with anti-cancer agents has failed to achieve satisfactory results in hepatocellular carcinoma. In the process of hepatocarcinogenesis, ras has been shown to play a role. ras requires a farnesyl moiety for activation. It has been found that UCFI-C (manumycin), an antibiotic, inhibits farnesyl protein transferase, an enzyme that catalyzes farnesylation. Therefore, we investigated the effects of UCFI-C on cell growth, prenylation of cellular proteins including ras and Rapl, MAP kinase activity, activities of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, and synthesis of cholesterol in a ras-activated human hepatoma cell line, Hep G2. Treatment with varying concentrations of UCF1-C(10-30 microM for 24 and 72 hr resulted in a time- and dose-dependent inhibition of cell numbers. 3H-Thymidine incorporation was also inhibited in a dose-dependent manner, with 50% inhibition after 44 hr being observed at a concentration of 17 microM. UCFI-C dose-dependently inhibited ras farnesylation and MAP kinase activity, but did not decrease Rap 1++ geranylgeranylation or prenylation of 21-to 26-kDa proteins. Neither the activities of 3-hydroxy-3-methylglutaryl-coenzyme A reductase nor cholesterol synthesis were inhibited. These results suggest that UCFI-C antagonizes the growth of Hep G2 via the suppression of ras farnesylation and could be a lead for the development of new anti-cancer agents blocking the function of oncogenic ras associated with human cancer, including hepatocellular carcinoma.

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

“…In accordance with several studies in other cell systems (Haklai et al, 1998;Kim et al, 1997;Nagase et al, 1996), treatment of the IBEC with Rasinhibitors inhibited FGF-2 induced cell proliferation. Our data suggest an obligatory signaling cascade to IBEC proliferation that starts with FGFR-1 activation, phosphorylation of the adaptor proteins Shc and FRS2 and subsequent activation of Ras followed by the linear Raf1/MEK/MAPK pathway.…”

The bisphosphonate zoledronic acid impairs membrane localisation and induces cytochrome c release in breast cancer cells

“…While ras mutations are not as common in breast cancer as in some other types of malignancy, the increased activity of growth factor signalling pathways which are mediated via Ras proteins makes targeting Ras action an attractive option in breast cancer treatment. By preventing maturation into its biologically active form, farnesyl transferase inhibitors (FTIs) abolish the membrane localisation (Lerner et al, 1995) and function of Ras (Nagase et al, 1996) and these agents are currently under evaluation in clinical trials in patients with breast cancer (Johnston and Kelland, 2001). We have determined if N-BPs can also prevent Ras processing leading to its cytoplasmic accumulation.…”

Manumycin inhibits ras signal transduction pathway and induces apoptosis in COLO320-DM human colon tumourcells

“…In this view, the aim of this study was to evaluate the effect of manumycin on the growth and ras protein isoprenylation of a cell line derived from a human colorectal cancer expressing a normal K-ras gene sequence. The effect of manumycin in cells harbouring a mutated and activated ras oncogene has been documented (Nagase et al, 1996). Therefore, the present study addressed the in vitro evaluation of manumycin in cells characterized by the presence of a normal ras gene as demonstrated by PCR analysis of K-ras sequence, in order to investigate whether the cytotoxicity of a FPTase inhibitor is limited to cells with a mutated ras gene or not.…”

“…Among them, manumycin is a promising compound derived from Streptomyces parvulus and characterized by Hara et al (1993). Manumycin acts via the specific inhibition of the farnesyl:protein transferase (FPTase), as demonstrated by the reversion of a ras-dependent phenotype in the worm Caenorhabditis elegans (Hara and Han, 1995) and exerts antiproliferative effect on human tumour cells which harbour a mutated K-ras gene (Nagase et al, 1996). However, the issue of therapeutic targeting of normal ras proteins has not been addressed and data are lacking concerning the ability of FPTase inhibitors to suppress the proliferation of tumour cells with wild-type K-ras genes.…”