u-0126 and mevastatin

Mevastatin which is an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis, suppress cell proliferation and induce apoptosis. However, the molecular mechanism of apoptosis induction is not well understood. So, in the present study, we attempted to clarify the mechanism by which mevastatin induces apoptosis in HL60 cells. It was found that mevastatin induced apoptosis. At that time, we observed an increase in caspase-3 activity and morphological fragmentation of the nuclei. The apoptosis induced by mevastatin was not inhibited by the addition of farnesyl pyrophosphate (FPP), squalene, ubiquinone, and isopentenyladenine, but was inhibited by the addition of geranylgeranyl pyrophosphate (GGPP). When we examined the survival signals at the time of apoptotic induction, we also observed that the administration of mevastatin had caused a remarkable decrease in the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). However, other survival signals, such as nuclear factor kappa B (NF-kappaB), protein kinase B (Akt), and p38 mitogen-activated protein kinase (p38), exhibited no change. In addition, no quantitative change was observed in Bcl-2, which was an anti-apoptosis protein. It was also observed that apoptosis was induced when U0126, an MEK inhibitor, was added to the cells to inhibit ERK. These results suggested that mevastatin induced apoptosis when it inhibited GGPP biosynthesis and consequently decreased the level of phosphorylated ERK, which was a survival signal; moreover, at that time, there was no influence on NF-kappaB, Akt, p38, and Bcl-2. The results of this study also suggested that mevastatin could be used as an anticancer agent.

Topics: Antineoplastic Agents; Apoptosis; Butadienes; Caspase 3; Caspases; Cell Nucleus; Extracellular Signal-Regulated MAP Kinases; HL-60 Cells; Humans; Lovastatin; Nitriles; Phosphorylation; Polyisoprenyl Phosphates; Protein Kinase Inhibitors

The present study shows that the incubation of human aortic smooth muscle cells (HASMC) and HepG2 cells with atorvastatin and mevastatin as HMG-CoA reductase inhibitors potentiated the interferon-gamma (INF-gamma)-induced group IIA phospholipase A(2) (sPLA(2)-IIA) expression in a dose- and time-dependent manner. The effect of statins on sPLA(2)-IIA expression was reduced by mevalonate, farnesyl pyrophosphate and geranylgeranyl pyrophosphate. Inversely, inhibitors of the farnesyl transferase and geranylgeranyl transferase-I mimicked the effects of statins. Clostridium difficile toxin B (TcdB), Y-27632 and H-1152, functioning as inhibitors of Rho proteins and Rho-associated kinase, also augmented the sPLA(2)-IIA expression in combination with IFN-gamma. The same effects were observed when inhibitors of mitogen-activated/extracellular response protein kinase kinase (MEK), PD98059 or U0126 were used. Further, the Janus kinase-2 (Jak2)-specific inhibitor, AG-490 and inhibitors of nuclear factor-kappaB (NFkappaB) abrogated the sPLA(2)-IIA elevating effects of statins, TcdB and PD98059 in the presence of IFN-gamma. This cytokine alone increased the NFkappaB p65 and CAAT-enhancer-binding protein-beta (C/EBP-beta) activity in HASMC nuclear extract, but only C/EBP-beta was further augmented when the cells were incubated in addition to IFN-gamma with atorvastatin, H-1152, PD98059 or U0126. Moreover, after the incubation of cells with atorvastatin and IFN-gamma the stability of sPLA-(2)IIA mRNA significantly increased in comparison to those after incubation with IFN-gamma alone. In conclusion, the obtained data suggest that (i) the expression of sPLA(2)-IIA is negatively regulated by RhoA/Rho-associated kinase and MEK/ERK signaling pathways and (ii) statins, because of their ability to down-regulate these pathways, can potentiate the IFN-gamma-induced sPLA(2)-II expression at transcriptional and post-transcriptional levels.

Topics: Amides; Aorta; Atorvastatin; Bacterial Proteins; Bacterial Toxins; Butadienes; Carcinoma, Hepatocellular; CCAAT-Enhancer-Binding Proteins; Cell Line, Tumor; Drug Synergism; Flavonoids; Group II Phospholipases A2; Heptanoic Acids; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Interferon-gamma; Janus Kinase 2; Lovastatin; Myocytes, Smooth Muscle; NF-kappa B; Nitriles; Phospholipases A; Phospholipases A2; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Pyridines; Pyrroles; RNA Stability; Up-Regulation