Delta-tocotrienol enhances the anti-tumor effects of interferon alpha through reactive oxygen species and Erk/MAPK signaling pathways in hepatocellular carcinoma cells.

The complexity of hepatocellular carcinoma (HCC) signaling and the failure of pharmacological therapeutics reveal the significance of establishing new anti-cancer strategies. Interferon alpha (IFN-α) has been used as adjuvant therapy for reducing HCC recurrence and improving survival. Delta-tocotrienol (δ-tocotrienol), a natural unsaturated isoform of vitamin E, is a promising candidate for cancer treatment. In this study, we evaluated whether the combination of δ-tocotrienol with IFN-α displays significant advantages in the treatment of HCC cells. Results showed that the combination significantly decreased cell viability, migration and invasion of HCC cells compared with single therapies. Combining δ-tocotrienol and IFN-α enhanced the decrease in proliferating cell nuclear antigen (PCNA) and matrix metalloproteinase (MMP) 7 and MMP-9. The combination also produced an enhancement of apoptosis together with increased Bax/Bcl-xL ratio and reactive oxygen species (ROS) generation. δ-tocotrienol induced Notch1 activation and changes in Erk and p38 MAPK signaling status. Blocking experiments confirmed that ROS and Erk are involved, at least in part, in the anti-cancer effects of the combined treatment. In conclusion, the combination of δ-tocotrienol with IFN-α therapy showed promising results for HCC cell treatment, which makes the combination of cytokine-based immunotherapy with natural products a potential strategy against liver cancer.

The chemoprotective effects of IFN-α-2b on rat hepatocarcinogenesis are blocked by vitamin E supplementation.

Many cancer patients receive their classical therapies together with vitamin supplements. However, the effectiveness of these strategies is on debate. Here we aimed to evaluate how vitamin E supplementation affects the anticancer effects of interferon (IFN-α) using an early-model of liver cancer development (initiation-promotion, IP). Male Wistar rats subjected to this model were divided as follows: untreated (IP), IP treated with recombinant IFN-α-2b (6.5  ×  105 U/kg), IP treated with vitamin E (50 mg/kg), and IP treated with combination of vitamin E and IFN-α-2b. After treatments rats were fasted and euthanized and plasma and livers were collected. Combined administration of vitamin E and IFN-α-2b induced body weight drop, increased liver apoptosis, and low levels of hepatic lipids. Interestingly, vitamin E and IFN-α-2b combination also induced an increase in altered hepatic foci number, but not in size. It seems that vitamin E acts on its antioxidant capability in order to block the oxidative stress induced by IFN-α-2b, blocking in turn its beneficial effects on preneoplastic livers, leading to harmful final effects. In conclusion, this study shows that vitamin E supplementation in IFN-α-2b-treated rats exerts unwanted effects; and highlights that in spite of being natural, nutritional supplements may not always exert beneficial outcomes when used as complementary therapy for the treatment of cancer.

IFN-α-2b induces apoptosis by decreasing cellular cholesterol levels in rat preneoplastic hepatocytes.

IFN-α administration to patients has been long discouraged and pushed back by new and apparently better drugs; however the adverse secondary effect, the high costs and the lack of specific action, make these new drugs hard to be used and put IFN-α again in the eye of the researchers. IFN-α-2b was demonstrated to induce apoptosis and modulation of lipid metabolism and the mechanisms are still unknown. Here, we sought to find the link between these features using a model of early stage cancer development. Using in vitro and in vivo approaches, we evaluated apoptosis and lipid metabolism. IFN-α-2b induced changes in hepatic cholesterol mass due to decreased synthesis and increased secretion. Interestingly, the drop in cellular cholesterol levels was necessary for IFN-α-2b to induce apoptosis. Results presented in this paper show the complexity of the action of IFN-α-2b on the early stages of liver cancer development. We show for the first time an interrelationship between cholesterol, apoptosis and IFN-α-2b. This makes clear the need for a reevaluation of IFN-α-2b action in order to develop softer, safer and more bearable derivatives. In this regard, knowing the molecular mechanisms by which IFN-α exerts its cellular actions is of crucial importance, and it is the main condition for therapy success for classical and new malignancies.

IFN-α-2b treatment protects against diet-induced obesity and alleviates non-alcoholic fatty liver disease in mice.

IFN-α is used for inflammatory purposes, and obesity and NAFLD are strongly correlated with inflammatory processes. We wondered whether IFN-α-2b can attenuate obesity development and its associated NAFLD in mice fed high fat diet (HFD) for 10 weeks. IFN-α-2b had a robust effect on body weight loss associated with NAFLD amelioration by decreasing hepatic inflammation. IFN-α-2b-treated mice showed increased plasma cholesterol levels together with decreased hepatic cholesterol, both on chow and HF diets. Interestingly, mice on IFN-α-2b treatment secreted smaller VLDL particles highly enriched in cholesterol. Mechanistically, we found that IFN-α-2b antiobesity effects were related to increased fatty acid oxidation; and its effects on cholesterol metabolism were due to both a decrease in the master cholesterogenic transcription factor SREBP-2 and in the rate limiting enzyme in cholesterol synthesis, HMGCR. To our knowledge, this is the first report showing the effects of IFN-α-2b on the prevention of the development of HFD-induced body weight gain and dyslipidemia through a mechanism that involves fatty acid oxidation and cholesterol decrease. These studies comprise necessary steps for understanding the amelioration of obesity and NAFLD. Results shed some light into the mechanism of action of natural cytokines, and their effects on ameliorating obesity and its related diseases.

Vitamin K2 supplementation blocks the beneficial effects of IFN-α-2b administered on the early stages of liver cancer development in rats.

OBJECTIVE: Vitamin K2, which is present in dairy products and has been recommended as a micronutrient supplement in humans, contains anticancer properties. Interferon (IFN)-α-2b administered during development of hepatic preneoplasia decreased both number and volume percentage of altered hepatic foci (AHF) by increasing apoptosis in the foci. The aim of this study was to evaluate the effects of IFN-α-2b treatment supplemented with vitamin K2 in the early stages of liver cancer development in rats. METHODS: Adult male Wistar rats were subjected to a two-phase model of hepatocarcinogenesis (initiated-promoted [IP] group). Animals were divided into four groups: untreated (IP), IP treated with IFN-α-2b (6.5 × 105 U/kg), IP treated with vitamin K2 (10 mg/kg), and IP treated with both compounds. RESULTS: The study results demonstrated that vitamin K2 blocked IFN-α-2b-induced reduction in size and volume of the altered hepatic foci and inhibited IFN-α-2b-induced apoptosis. Its inhibition of IFN-α-2b-induced apoptosis was mediated by increased levels of total hepatic Bcl-2 in rat preneoplastic livers. CONCLUSION: These findings demonstrate that supportive vitamin supplements or therapies are not always safe because they could put the life of patients treated with IFN-α-2b at risk.

Hepatic carboxylesterase 3 (Ces3/Tgh) is downregulated in the early stages of liver cancer development in the rat.

It is accepted that cancer development is associated with metabolic changes. Previously, we established a model of hepatic preneoplasia in which adult rats were subjected to a 2-phase model of hepatocarcinogenesis (initiated-promoted, IP) for 6weeks until they develop altered hepatic foci (AHF). Here, we found that a whole metabolic shift occurs in order to favor cancer development. IP animals presented with increased plasma lipids due to increased VLDL secretion as well as increased liver lipid accretion due to stimulated transacetylase activity rather than lipogenesis, compared to control rats. We found that carboxylesterase 3/triacylglycerol hydrolase (Ces3/Tgh) presented with a perilobular distribution surrounding lipid droplets in normal livers. However, it is downregulated both at the protein and mRNA level in liver homogenates and is almost undetectable inside the AHF with no changes in the surrounding tissue. Ces3/Tgh expression is regulated by ω-3 fatty acids, thus, supplementation of diet with fish oil, allowed the restoration of Ces3/Tgh expression inside the foci and, more interestingly, led to the decrease in number and volume of the AHF. These studies show a preventive role of Ces3/Tgh in liver cancer development.