plastochromanol-8 and Liver-Neoplasms

Tocotrienol (T3) has recently gained increasing interest due to its anti-cancer effect. Here, we investigated the modulating effect of δ and γ T3 on the Ras-Raf-MEK-ERK oncogenic upstream signaling pathway in human hepatocellular carcinoma HepG2 cells. The results indicated that T3 regulated the upstream signaling cascades of this pathway.

Topics: Carcinoma, Hepatocellular; Cell Proliferation; Chromans; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Hep G2 Cells; Humans; Liver Neoplasms; MAP Kinase Kinase Kinases; raf Kinases; ras Proteins; Signal Transduction; Vitamin E

To determine the antiproliferative effect of gamma-tocotrienol (GTT) treatment on differential protein expression in HepG2 cells.. HepG2 cells were treated with 70 μM GTT for 48 hours and differentially expressed protein spots were determined by two-dimensional electrophoresis (2DE), identified by MALDI-TOF mass spectrometer (MS) and validated by quantitative real-time polymerase chain reaction (qRT-PCR).. GTT treatment on HepG2 cells showed a total of five differentially expressed proteins when compared to their respective untreated cells where three proteins were down-regulated and two proteins were up-regulated. One of these upregulated proteins was identified as peroxiredoxin-4 (Prx4). Validation by qRT-PCR however showed decreased expression of Prx4 mRNA in HepG2 cells following GTT treatment.. GTT might directly influence the expression dynamics of peroxiredoxin-4 to control proliferation in liver cancer.

Topics: Antineoplastic Agents; Antioxidants; Bile Duct Neoplasms; Chromans; Down-Regulation; Electrophoresis, Gel, Two-Dimensional; Hep G2 Cells; Hepatoblastoma; Humans; Liver; Liver Neoplasms; Peroxiredoxins; Proteins; Proteomics; Real-Time Polymerase Chain Reaction; RNA, Messenger; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tocotrienols; Up-Regulation; Vitamin E; Vitamins

Angiogenesis is one of the key hallmarks of cancer. In this study, we investigated whether γ-tocotrienol can abrogate angiogenesis-mediated tumor growth in hepatocellular carcinoma (HCC) and if so, through what molecular mechanisms. We observed that γ-tocotrienol inhibited vascular endothelial growth factor (VEGF)-induced migration, invasion, tube formation and viability of HUVECs in vitro. Moreover, γ-tocotrienol reduced the number of capillary sprouts from matrigel embedded rat thoracic aortic ring in a dose-dependent manner. Also, in chick chorioallantoic membrane assay, γ-tocotrienol significantly reduced the blood vessels formation. We further noticed that γ-tocotrienol blocked angiogenesis in an in vivo matrigel plug assay. Furthermore, γ-tocotrienol inhibited VEGF-induced autophosphorylation of VEGFR2 in HUVECs and also suppressed the constitutive activation of AKT/mammalian target of rapamycin (mTOR) signal transduction cascades in HUVECs as well as in HCC cells. Interestingly, γ-tocotrienol was also found to significantly reduce the tumor growth in an orthotopic HCC mouse model and inhibit tumor-induced angiogenesis in HCC patient xenografts through the suppression of various biomarkers of proliferation and angiogenesis. Taken together, our findings strongly suggest that γ-tocotrienol might be a promising anti-angiogenic drug with significant antitumor activity in HCC.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Chick Embryo; Chromans; Endothelial Cells; Humans; Ki-67 Antigen; Liver Neoplasms; Mice; Mice, SCID; Models, Animal; Neovascularization, Pathologic; Proto-Oncogene Proteins c-akt; Signal Transduction; Vascular Endothelial Growth Factor A; Vitamin E

Vitamin E is the generic name for tocopherol (Toc) and tocotrienol (T3), which have saturated and unsaturated side chains, respectively. Such differences allow T3 to be different from Toc in terms of their functions. T3 has been known to attenuate cholesterol (Cho) level by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoAR). Recent reports also showed the efficacy of T3 in improving triglyceride (TG) profiles in both in vivo and in vitro studies. However the mechanism involved in this biological activity is still unclear and needs to be further investigated. In the present study, we elucidated the effect of γ-T3 on lipid levels and lipogenic gene expressions in mouse hepatocellular carcinoma Hepa 1-6. γ-T3 showed attenuation of TG through effect on fatty acid synthase, sterol regulatory element-binding transcription factor 1, stearoyl CoA desaturase 1, and carnitine palmitoyl transferase 1A gene expression in Hepa 1-6. In contrast, the Cho level remained unchanged. These results expanded our previous finding of lipid-lowering effects of T3, especially for TG. Therefore, T3 is a potential lipid-lowering compound candidate with realistic prospects for its use as a therapy for lipid-related diseases in humans.

Topics: Animals; Carcinoma, Hepatocellular; Carnitine O-Palmitoyltransferase; Cell Line, Tumor; Cholesterol; Chromans; Fatty Acid Synthases; Gene Expression; Hydroxymethylglutaryl CoA Reductases; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lipogenesis; Liver Neoplasms; Mice; Mice, Inbred C57BL; RNA, Messenger; Stearoyl-CoA Desaturase; Sterol Regulatory Element Binding Protein 1; Triglycerides; Vitamin E

Activation of signal transducer and activator of transcription 3 (STAT3) play a critical role in the survival, proliferation, angiogenesis and chemoresistance of tumour cells. Thus, agents that suppress STAT3 phosphorylation have potential as cancer therapies. In the present study, we investigated whether the apoptotic, antiproliferative and chemosensitizing effects of γ-tocotrienol are associated with its ability to suppress STAT3 activation in hepatocellular carcinoma (HCC).. The effect of γ-tocotrienol on STAT3 activation, associated protein kinases and phosphatase, STAT3-regulated gene products, cellular proliferation and apoptosis in HCC cells was investigated.. γ-Tocotrienol inhibited both the constitutive and inducible activation of STAT3 with minimum effect on STAT5. γ-Tocotrienol also inhibited the activation of Src, JAK1 and JAK2 implicated in STAT3 activation. Pervanadate reversed the γ-tocotrienol-induced down-regulation of STAT3, suggesting the involvement of a protein tyrosine phosphatase. Indeed, we found that γ-tocotrienol induced the expression of the tyrosine phosphatase SHP-1 and deletion of the SHP-1 gene by small interfering RNA abolished the ability of γ-tocotrienol to inhibit STAT3 activation. γ-Tocotrienol also down-regulated the expression of STAT3-regulated gene products, including cyclin D1, Bcl-2, Bcl-xL, survivin, Mcl-1 and vascular endothelial growth factor. Finally, γ-tocotrienol inhibited proliferation, induced apoptosis and significantly potentiated the apoptotic effects of chemotherapeutic drugs (paclitaxel and doxorubicin) used for the treatment of HCC.. Overall, these results suggest that γ-tocotrienol is a novel blocker of the STAT3 activation pathway, with a potential role in future therapies for HCC and other cancers.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Chromans; Doxorubicin; Drug Resistance, Neoplasm; Drug Synergism; Enzyme Activation; Enzyme Induction; Genes, Reporter; Humans; Janus Kinases; Liver Neoplasms; NF-kappa B; Paclitaxel; Phosphorylation; Protein Kinase Inhibitors; Protein Tyrosine Phosphatases; Proto-Oncogene Proteins c-akt; Signal Transduction; src-Family Kinases; STAT3 Transcription Factor; Vitamin E

Present study aimed to elucidate the suppression of serum lipids by gamma- and delta-tocotrienol (γδT3).. The lipid-lowering effects of γδT3 were investigated using HepG2 liver cell line, hypercholesterolemic mice and borderline-high cholesterol patients.. In-vitro results demonstrated two modes of action. First, γδT3 suppressed the upstream regulators of lipid homeostasis genes (DGAT2, APOB100, SREBP1/2 and HMGCR) leading to the suppression of triglycerides, cholesterol and VLDL biosyntheses. Second, γδT3 enhanced LDL efflux through induction of LDL receptor (LDLr) expression. Treatment of LDLr-deficient mice with 1 mg/day (50 mg/kg/day) γδT3 for one-month showed 28%, 19% reduction in cholesterol and triglyceride levels respectively, whereas HDL level was unaltered. The lipid-lowering effects were not affected by alpha-tocopherol (αTP). In a placebo-controlled human trial using 120 mg/day γδT3, only serum triglycerides were lowered by 28% followed by concomitant reduction in the triglyceride-rich VLDL and chylomicrons. In contrast, total cholesterol, LDL and HDL remained unchanged in treated and placebo groups. The discrepancies between in-vitro, in-vivo and human studies may be attributed to the differential rates of post-absorptive γδT3 degradation and LDL metabolism.. Reduction in triglycerides synthesis and transport may be the primary benefit caused by ingesting γδT3 in human.

Topics: Animals; Apolipoprotein B-100; Blotting, Western; Carcinoma, Hepatocellular; Cell Proliferation; Cells, Cultured; Chromans; Diacylglycerol O-Acyltransferase; Female; Humans; Hydroxymethylglutaryl CoA Reductases; Lipoproteins, VLDL; Liver; Liver Neoplasms; Male; Mice; Mice, Knockout; Receptors, LDL; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sterol Regulatory Element Binding Protein 1; Sterol Regulatory Element Binding Protein 2; Triglycerides; Vitamin E

We evaluated the antitumor activity of tocotrienol (T3) on human hepatoma Hep3B cells. At first, we examined the effect of T3 on the proliferation of human hepatoma Hep3B cells and found that gamma-T3 inhibited cell proliferation at lower concentrations and shorter treatment times than alpha-T3. Then, we examined the effect of gamma-T3 apoptosis induction and found that gamma-T3 induced poly (ADP-ribose) polymerase (PARP) cleavage and stimulated a rise in caspase-3 activity. In addition, gamma-T3 stimulated a rise in caspase-8 and caspase-9 activities. We also found that gamma-T3-induced apoptotic cell death was accompanied by up-regulation of Bax and a rise in the fragments of Bid and caspase-8. These data indicate that gamma-T3 induced apoptosis in Hep3B cells and that caspase-8 and caspase-9 were involved in apoptosis induction. Moreover, these results suggest that Bax and Bid regulated apoptosis induction by gamma-T3.

Topics: Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Division; Cell Line, Tumor; Chromans; Gene Expression; Genes, bcl-2; Humans; Liver Neoplasms; Poly(ADP-ribose) Polymerases; Tocotrienols; Vitamin E

Tocotrienols are natural farnesylated analogues of tocopherols which decrease hepatic cholesterol production and reduce plasma cholesterol levels in animals. For several cultured cell types, incubation with gamma-tocotrienol inhibited the rate of [14C]acetate but not [3H] mevalonate incorporation into cholesterol in a concentration- and time-dependent manner, with 50% inhibition at approximately 2 microM and maximum approximately 80% inhibition observed within 6 h in HepG2 cells. 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase total activity and protein levels assayed by Western blot were reduced concomitantly with the decrease in cholesterol synthesis. In HepG2 cells, gamma-tocotrienol suppressed reductase despite strong blockade by inhibitors at several steps in the pathway, suggesting that isoprenoid flux is not required for the regulatory effect. HMG-CoA reductase protein synthesis rate was moderately diminished (57% of control), while the degradation rate was increased 2.4-fold versus control (t1/2 declined from 3.73 to 1.59 h) as judged by [35S]methionine pulse-chase/immunoprecipitation analysis of HepG2 cells treated with 10 microM gamma-tocotrienol. Under these conditions, the decrease in reductase protein levels greatly exceeded the minor decrease in mRNA (23 versus 76% of control, respectively), and the low density lipoprotein receptor protein was augmented. In contrast, 25-hydroxycholesterol strongly cosuppressed HMG-CoA reductase protein and mRNA levels and the low density lipoprotein receptor protein. Thus, tocotrienols influence the mevalonate pathway in mammalian cells by post-transcriptional suppression of HMG-CoA reductase, and appear to specifically modulate the intracellular mechanism for controlled degradation of the reductase protein, an activity that mirrors the actions of the putative non-sterol isoprenoid regulators derived from mevalonate.

Topics: Acetates; Acetic Acid; Androstenes; Animals; Carbon Radioisotopes; Carcinoma, Hepatocellular; Cell Line; Chickens; CHO Cells; Cholesterol; Chromans; Cricetinae; Gene Expression Regulation, Enzymologic; Humans; Hydroxycholesterols; Hydroxymethylglutaryl CoA Reductases; Ketoconazole; Kinetics; Liver Neoplasms; Liver Neoplasms, Experimental; Lovastatin; Mevalonic Acid; Rats; RNA Processing, Post-Transcriptional; RNA, Messenger; Suppression, Genetic; Tritium; Tumor Cells, Cultured; Vitamin E