geranylgeranyl-pyrophosphate and Multiple-Myeloma

Multiple myeloma (MM) is a plasma cell malignancy that is often driven by chromosomal translocations. In particular, patients with t(4;14)-positive disease have worse prognosis compared to other MM subtypes. Herein, we demonstrated that t(4;14)-positive cells are highly dependent on the mevalonate (MVA) pathway for survival. Moreover, we showed that this metabolic vulnerability is immediately actionable, as inhibiting the MVA pathway with a statin preferentially induced apoptosis in t(4;14)-positive cells. In response to statin treatment, t(4;14)-positive cells activated the integrated stress response (ISR), which was augmented by co-treatment with bortezomib, a proteasome inhibitor. We identified that t(4;14)-positive cells depend on the MVA pathway for the synthesis of geranylgeranyl pyrophosphate (GGPP), as exogenous GGPP fully rescued statin-induced ISR activation and apoptosis. Inhibiting protein geranylgeranylation similarly induced the ISR in t(4;14)-positive cells, suggesting that this subtype of MM depends on GGPP, at least in part, for protein geranylgeranylation. Notably, fluvastatin treatment synergized with bortezomib to induce apoptosis in t(4;14)-positive cells and potentiated the anti-tumor activity of bortezomib in vivo. Our data implicate the t(4;14) translocation as a biomarker of statin sensitivity and warrant further clinical evaluation of a statin in combination with bortezomib for the treatment of t(4;14)-positive disease.

Topics: Animals; Antineoplastic Agents; Apoptosis; Biomarkers, Tumor; Bortezomib; Cell Proliferation; Chromosomes, Human, Pair 14; Chromosomes, Human, Pair 4; Female; Fluvastatin; Gene Expression Regulation, Neoplastic; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Mevalonic Acid; Mice; Mice, Inbred NOD; Mice, SCID; Multiple Myeloma; Polyisoprenyl Phosphates; Translocation, Genetic; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Thalidomide has emerged as an effective agent for treating multiple myeloma, however the precise mechanism of action remains unknown. Agents known to target the isoprenoid biosynthetic pathway (IBP) can have cytotoxic effects in myeloma cells. The interactions between thalidomide and IBP inhibitors in human multiple myeloma cells were evaluated. Enhanced cytotoxicity and induction of apoptosis were observed in RPMI-8226 cells. Examination of intracellular levels of farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) revealed a wide variance in basal levels and response to IBP inhibitors. These findings provide a mechanism for the differential sensitivity of myeloma cells to pharmacologic manipulation of the IBP.

Topics: Antineoplastic Agents; Apoptosis; Biosynthetic Pathways; Blotting, Western; Cell Line, Tumor; Cell Separation; Flow Cytometry; Humans; Multiple Myeloma; Polyisoprenyl Phosphates; Sesquiterpenes; Terpenes; Thalidomide

Macrophage inflammatory protein 1 alpha (MIP-1 alpha) is detected at high concentrations in patients with multiple myeloma, and it is thought to play an important role in the etiology of multiple myeloma and osteolysis. Thus, we investigated whether or not YM529/ONO-5920, a new bisphosphonate, inhibited MIP-1 alpha mRNA expression in, and MIP-1 alpha secretion from, mouse myeloma cells. When the cells were stimulated by lipopolysaccharide, increased MIP-1 alpha mRNA expression and MIP-1 alpha secretion were observed. YM529/ONO-5920 inhibited MIP-1 alpha mRNA expression and MIP-1 alpha secretion in a concentration-dependent manner. A transient increase in the phosphorylation of extracellular-regulated kinase 1/2 (ERK1/2) and Akt was observed after lipopolysaccharide stimulation. After YM529/ONO-5920 was given, there was no transient increase in the phosphorylation of ERK1/2 or Akt. These results indicated that YM529/ONO-5920 inhibited the expression and secretion of MIP-1 alpha through blocking the signaling pathway of the Ras/mitogen-activated protein kinase kinase/ERK and Ras/phosphatidylinositol-3 kinase/Akt. Accordingly, YM529/ONO-5920 appears to have promise for use in effective future therapy for osteolysis and myeloma cell growth that depends on MIP-1 alpha.

Topics: Animals; Butadienes; Cell Growth Processes; Cell Line, Tumor; Chemokine CCL3; Chromones; Diphosphonates; I-kappa B Proteins; Imidazoles; Lipopolysaccharides; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Morpholines; Multiple Myeloma; Nitriles; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Polyisoprenyl Phosphates; Proto-Oncogene Proteins c-akt; RNA, Messenger; Sesquiterpenes

Prenylation is essential for membrane localization and participation of proteins in various signaling pathways. This study examined the role of farnesylated and geranylgeranylated proteins in the regulation of myeloma cell proliferation.. Antiproliferative and apoptotic effects of various modulators of farnesylated and geranylgeranylated proteins were investigated in myeloma cells.. Depletion of geranylgeranylpyrophosphate inhibited myeloma cell proliferation through accumulation of cells in G(1) phase of the cell cycle and loss of cells in S phase. In contrast, depletion of farnesylpyrophosphate had no or only minor effects. Furthermore, inhibition of geranylgeranyl transferase I activity was more effective in reducing myeloma cell growth when compared with inhibition of farnesyl transferase activity. This indicates that protein geranylgeranylation is important for myeloma cell proliferation and cell cycle progression through G(1). Geranylgeranylated target proteins involved in the control of proliferation include GTPases, such as Rac-1, Cdc42, and RhoA. Inhibition of Rho, Rac, and Cdc42 GTPases by toxin B reduced proliferation, without affecting cell viability, whereas specific inhibition of Rho GTPases by C3 exoenzyme was without effect. This suggests a role for Rac and/or Cdc42 GTPases in myeloma cell growth. Rac-1 activity was found in all myeloma cell lines and was suppressed by the depletion of intracellular pools of geranylgeranylpyrophosphate, whereas interleukin-6 rapidly induced Rac-1 activation. Furthermore, dominant-negative Tat-Rac-1 reduced myeloma cell proliferation, whereas constitutively active Tat-Rac-1 enhanced proliferation.. These results indicate that protein geranylgeranylation is essential for myeloma cell proliferation and suggest that Rac-1 is a regulator of myeloma cell growth.

Topics: Aged; Alkyl and Aryl Transferases; cdc42 GTP-Binding Protein; Cell Proliferation; Farnesyltranstransferase; Female; Genes, Dominant; Humans; Interleukin-6; Male; Middle Aged; Multiple Myeloma; Polyisoprenyl Phosphates; Protein Prenylation; Protein Processing, Post-Translational; rac1 GTP-Binding Protein; rhoA GTP-Binding Protein; Sesquiterpenes; Tumor Cells, Cultured