Effect of farnesyl transferase inhibitor R115777 on the growth of fresh and cloned myeloma cells in vitro

Abstract

Ras gene mutations occur in 30% to 40% of patients with multiple myeloma (MM), and farnesylation is the first and most important step in the posttranslational modification of Ras proteins. R115777 is a newly synthesized potent farnesyl transferase inhibitor (FTI) and has recently demonstrated significant antitumor activities in vitro and in vivo. Therefore, we examined the effect of R115777 on the growth of fresh and cloned myeloma cells in vitro. R115777 inhibited the growth of fresh and cloned myeloma cells dose dependently, and effects were not dependent on the status of N-Ras mutation in fresh myeloma cells. Flow cytometric analysis using annexin V and 7-aminoactinomycin D (7AAD) showed that R115777 induced apoptosis of 2 of 3 myeloma cell lines at a concentration of 1.0 ؋ 10 ؊8 M. R115777 appears to be a potent inducer of apoptosis, and its effects depend on the status of Ras mutation in cloned myeloma cells but not on IntroductionMultiple myeloma (MM) is a malignancy of B cells characterized by the monoclonal proliferation of malignant plasma cells and osteolytic bone destruction. Several chemotherapeutic regimens have been used to improve the survival of patients with MM. Although high-dose melphalan supported by autologous stem cell transplantation (auto-SCT) has improved the survival of patients with MM, many patients were found to relapse during a long follow-up period. 1,2 Allogeneic stem cell transplantation (allo-SCT) is possibly the only genuinely curative therapy for MM, and a graft-versus-myeloma effect by immunocompetent donor lymphocytes has been demonstrated but the treatment-related mortality is high. 3,4 Recently, nonmyeloablative SCT has been reported to provide a stable engraftment of allogeneic stem cells and tolerable toxicity in patients with MM, but a longer follow-up period is necessary to evaluate late mortality. 5,6 Therefore, there is an obvious need for new therapeutic strategies.Ras proteins are prototypical G proteins that have been shown to play a key role in signal transduction, cell proliferation, and malignant transformation. Ligand-stimulated activation of the cell-surface receptor, receptor-associated tyrosine kinase, or agonist mediated through G protein-coupled receptors results in the activation of Ras protein. The Ras gene family consists of 3 functional genes, H-Ras, N-Ras, and K-Ras. Activating point mutations in all 3 Ras genes have been detected in a wide variety of human malignancies and are one of the most common alternations in hematologic malignancies. [7][8][9] In MM, Ras gene activation is observed in 30% to 40% of cases and one of the most frequent point mutations. [10][11][12][13] Although Ras protein undergoes several steps of posttranslational modification, farnesylation is the first and most important step for its membrane localization and cell-transforming activity. Thus, farnesyltransferase (FTase) is a very attractive target for the development of anticancer agents. R115777 (Zarnestra, Johnson & Johnson, Raritan, NJ), a potent and selective farnesy...

Optimization and apoptosis induction by RNAi with UTMD technology in vitro

“…Cells were assessed by flow cytometry (FACSCalibur, BectonDickinson) following the double staining of cells with annexin V and 7-AAD (Jinmei Biotech Co. Ltd., Wuhan, China). Early apoptotic cells were stained with FITC-labelled annexin-V alone, whereas necrotic and late apoptotic cells were stained with annexin V and 7-AAD (29). Each assay was performed three times.…”

Importance of the bone marrow microenvironment in inducing the angiogenic response in multiple myeloma

“…Furthermore, inhibition of either p38MAPK or TFG-b by specific inhibitors downregulates IL-6 secretion in BMSC Hideshima et al, 2004). Targeting inhibition of Ras/Raf/MEK/ERK signaling by using the farnesyltransferase inhibitors SCH66336 and R115777 abrogates plasma cell growth (Ochiai et al, 2003). The proteasome inhibitor bortezomib (formerly PS-341) can overcome the protective effect of IL-6 against dex-induced apoptosis in MM by inducing caspase-8/-9/-3 activation, which results in caspase-dependent gp130 cleavage (Hideshima et al, 2001b(Hideshima et al, , 2003b.…”

The combination of the farnesyl transferase inhibitor lonafarnib and the proteasome inhibitor bortezomib induces synergistic apoptosis in human myeloma cells that is associated with down-regulation of p-AKT

“…The proteasome inhibitor bortezomib is an agent that has multiple different potential mechanisms of action including, but not limited to, inhibition of nuclear translocation of nuclear factor kB (NFkB), activation of the c-Jun N-terminal kinase (JNK) pathway, regulation of cyclin-dependent kinases, and regulation of other apoptotic proteins. [6][7][8] The farnesyl transferase inhibitors (FTIs) have historically been agents directed at the Ras/Raf/mitogen-activated protein kinase (MAPK) pathway, 9,10 however, emerging data suggests that among patients with responses to the FTIs, these occur independent of Ras mutations. 11 The clinical and preclinical experience with the FTIs in human cancers has been mixed.…”