tretinoin and mevastatin

Neural apoptosis-regulated convertase (NARC)-1 is the newest member of the proprotein convertase family implicated in the cleavage of a variety of protein precursors. The NARC-1 gene, PCSK9, has been identified recently as the third locus implicated in autosomal dominant hypercholesterolemia (ADH). The 2 other known genes implicated in ADH encode the low-density lipoprotein receptor and apolipoprotein B. As an approach toward the elucidation of the physiological role(s) of NARC-1, we studied its transcriptional regulation.. Using quantitative RT-PCR, we assessed NARC-1 regulation under conditions known to regulate genes involved in cholesterol metabolism in HepG2 cells and in human primary hepatocytes. We found that NARC-1 expression was strongly induced by statins in a dose-dependent manner and that this induction was efficiently reversed by mevalonate. NARC-1 mRNA level was increased by cholesterol depletion but insensitive to liver X receptor activation. Human, mouse, and rat PCSK9 promoters contain 2 typical conserved motifs for cholesterol regulation: a sterol regulatory element (SRE) and an Sp1 site.. PCSK9 regulation is typical of that of the genes implicated in lipoprotein metabolism. In vivo, PCSK9 is probably a target of SRE-binding protein (SREBP)-2.

Topics: Alitretinoin; Animals; Atorvastatin; Base Sequence; Cell Line; Cholesterol; Consensus Sequence; DNA-Binding Proteins; Gene Expression Regulation; Hepatocytes; Heptanoic Acids; Homeostasis; Humans; Hydroxycholesterols; Hydroxymethylglutaryl CoA Reductases; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Liver X Receptors; Lovastatin; Mevalonic Acid; Mice; Orphan Nuclear Receptors; Promoter Regions, Genetic; Proprotein Convertase 9; Proprotein Convertases; Pyridines; Pyrroles; Quinolines; Rats; Receptors, Cytoplasmic and Nuclear; Regulatory Sequences, Nucleic Acid; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sequence Alignment; Sequence Homology, Nucleic Acid; Serine Endopeptidases; Simvastatin; Sp1 Transcription Factor; Species Specificity; Sterol Regulatory Element Binding Protein 2; Transcription Factors; Tretinoin

Embryonic stem (ES) cells have the capacity to differentiate into various cell types in vitro. In this study, we show that retinoic acid is important for the commitment of ES cells into osteoblasts. Culturing retinoic acid treated ES cells in the presence of the osteogenic supplements ascorbic acid and beta-glycerophosphate resulted in the expression of several osteoblast marker genes, osteocalcin, alkaline phosphatase, and osteopontin. However, there was only a slight amount of mineralized matrix secretion. Addition of bone morphogenic protein-2 or compactin, a drug of the statin family of HMG-CoA reductase inhibitors, resulted in a greatly enhanced formation of bone nodules. Compactin did not modify the expression of osteogenic markers, but at the late stage of differentiation promoted an increase in BMP-2 expression. These results establish ES-cell derived osteogenesis as an effective model system to study the molecular mechanisms by which the statin compactin promotes osteoblastic differentiation and bone nodule formation.

Topics: Alkaline Phosphatase; Animals; Antigens, Differentiation; Ascorbic Acid; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Cell Differentiation; Cells, Cultured; Glycerophosphates; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lovastatin; Mice; Osteoblasts; Osteocalcin; Osteogenesis; Osteopontin; RNA, Messenger; Sialoglycoproteins; Stem Cells; Transforming Growth Factor beta; Tretinoin

Statins (cholesterol lowering drugs) with a closed-ring structure (lovastatin, simvastatin and mevastatin) and an open-ring structure (pravastatin and fluvastatin) are currently used in the management of cardiac disease. Lovastatin and simvastatin inhibit the growth of tumor cells; however, the studies on the effect of a statin in combination with micronutrients such as alpha-tocopheryl succinate (alpha-TS), 13-cis retinoic acid (RA) and polar carotenoids (PC) have never been performed. The primary objective of this study was to investigate the effect of mevastatin alone and in combination with the above micronutrients on the growth of mouse neuroblastoma (NB) cells and rat immortalized dopamine (DA) neurons in culture. In addition, a comparative efficacy of mevastatin and pravastatin on the growth of NB cells was studied.. Cells were treated with mevastatin in combination with individual antioxidants, alpha-TS, RA and polar carotenoids, 24 hours after plating. Fresh growth medium and agents were changed at two days after treatment, and the viability in control and experimental groups was determined at three days after treatment by MTT assay. Each experiment was repeated three times with triplicate samples per treatment. Growth in experimental groups was expressed as % of untreated cells.. Mevastatin inhibited the growth of neuroblastoma (NB) cells and immortalized, non-tumorigenic dopamine (DA) neurons in culture in a dose-dependent manner. Immortalized DA neurons were more sensitive to mevastatin than NB cells. Pravastatin at similar concentrations was ineffective in inhibiting the growth of NB cells. Mevastatin in combination with alpha-TS, RA or PC was more effective in reducing the growth of NB and DA neurons than the individual agents.. Statins with a closed-ring structure can inhibit the growth of established cancer cells as well as immortalized cells (equivalent to pre-malignant lesion), whereas statins with an open-ring structure may be ineffective. A combination of a statin having a closed-ring structure with alpha-TS, RA and PC may be one of the potentially useful anti-cancer agents for prevention and treatment strategies.

Topics: Animals; Anticholesteremic Agents; Antineoplastic Agents; Antioxidants; Carotenoids; Cell Line, Transformed; Cells, Cultured; Chromatography, High Pressure Liquid; Lovastatin; Mice; Neurons; Pravastatin; Rats; Tocopherols; Tretinoin; Vitamin E

The resistance to all trans retinoic acid (ATRA) differentiating treatment is a consequence, in most of the cases, of either increased catabolism or down regulation of ATRA uptake. Recently, we have shown that ATRA efficiency to differentiate HL-60 cells was enhanced about 30 times after its incorporation into Low Density Lipoprotein (ATRA-LDL). Here, we attempted to differentiate the ATRA-resistant HL-60 cells by ATRA-LDL at high concentrations up to 10 microM. No significant differentiating effect was observed, although the LDL receptor sites were evidenced in these cells. To increase the number of LDL receptors, the cells were pre-incubated in lipoprotein-deprived serum medium and compactin (2 microM), both ATRA and ATRA-LDL induced gradual increase of cell differentiation (35%+/-1 and 51.5%+/-5 at 10 microM of ATRA and ATRA-LDL respectively). At 2 and 8 microM, the intracellular concentrations of ATRA were respectively three and four times higher when incorporated into LDL. In addition, ATRA-LDL, in the medium, was better protected against degradation than ATRA. The surprising restoration of free ATRA sensitivity after treatment with compactin suggested the implication of new mechanisms unrelated to the LDL-receptor endocytosis but involving the non-sterol pathway.

Topics: Antineoplastic Agents; Binding, Competitive; Chromatography, High Pressure Liquid; Drug Interactions; Drug Screening Assays, Antitumor; HL-60 Cells; Humans; Leukemia; Lovastatin; Receptors, LDL; Tretinoin; Tumor Cells, Cultured