A trans-fatty acid-rich diet promotes liver tumorigenesis in HCV core gene transgenic mice

Abstract

Excess consumption of trans-fatty acid (TFA), an unsaturated fatty acid containing trans double bonds, is a major risk factor for cardiovascular disease and metabolic syndrome. However, little is known about the link between TFA and hepatocellular carcinoma (HCC) despite it being a frequent form of cancer in humans. In this study, the impact of excessive dietary TFA on hepatic tumorigenesis was assessed using hepatitis C virus (HCV) core gene transgenic mice that spontaneously developed HCC. Male transgenic mice were treated for 5 months with either a control diet or an isocaloric TFA-rich diet that replaced the majority of soybean oil with shortening. The prevalence of liver tumors was significantly higher in TFA-rich diet-fed transgenic mice compared with control diet-fed transgenic mice. The TFA-rich diet significantly increased the expression of pro-inflammatory cytokines, as well as oxidative and endoplasmic reticulum stress, and activated nuclear factor-kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (NRF2), leading to high p62/sequestosome 1 (SQSTM1) expression. Furthermore, the TFA diet activated extracellular signal-regulated kinase (ERK) and stimulated the Wnt/β-catenin signaling pathway, synergistically upregulating cyclin D1 and c-Myc, driving cell proliferation. Excess TFA intake also promoted fibrogenesis and ductular reaction, presumably contributing to accelerated liver tumorigenesis. In conclusion, these results demonstrate that a TFA-rich diet promotes hepatic tumorigenesis, mainly due to persistent activation of NF-κB and NRF2-p62/SQSTM1 signaling, ERK and Wnt/β-catenin pathways and fibrogenesis. Therefore, HCV-infected patients should avoid a TFA-rich diet to prevent liver tumor development.

Phospholipids are A Potentially Important Source of Tissue Biomarkers for Hepatocellular Carcinoma: Results of a Pilot Study Involving Targeted Metabolomics

“…The finding of palmitelaidic acid in our FFA signatures is also intriguing, since it is a trans fatty acid whose major dietary sources are hydrogenated vegetable oils and dairy fats. Trans fatty acid-rich diets have been shown to increase liver tumorigenesis in mouse models [36]. Recent studies have also suggested that lipid desaturation (i.e., formation of double bonds in the fatty acyl chains) also occurs more frequently in cancer cells, providing additional opportunities to interfere with cancer cell fatty acid metabolism by targeting the desaturase enzymes [37,38].…”

Dietary Restriction Suppresses Steatosis-Associated Hepatic Tumorigenesis in Hepatitis C Virus Core Gene Transgenic Mice

“…The diet was purchased from Research Diets Inc. (New Brunswick, NJ, USA). Mice in the former group were also used as the controls in the other studies [16,17]. A 30% decrease in food was selected as the DR intervention for the following two reasons: (1) a 30% food reduction protocol was reported to attenuate obesity and improve metabolic profiles without malnutrition in previous studies [10,11]; (2) this DR dose maintained the mouse body weight constant for the long term, preventing age-dependent body weight gain as determined by preliminary studies.…”

“…Total liver lipids were extracted according to the hexane:isopropanol method [18] and measured using the identical kits (Wako Pure Chemical Industries Ltd). Hepatic hydroxyproline concentrations were measured using the QuickZyme Hydroxyproline Assay kit (QuickZyme BioSciences, Leiden, The Netherlands) as described elsewhere [16,17].…”

“…Total liver RNA was extracted using NucleoSpin RNA Plus Kit (Macherey-Nagel GmbH & Co. KG, Düren, Germany) and cDNA was reverse-transcribed with ReverTra Ace ® quantitative polymerase chain reaction (qPCR) RT Master Mix (Toyobo, Osaka, Japan). The levels of mRNA were quantified using an SYBR qPCR kit (Toyobo) and Applied Biosystems StepOne Plus Real-time PCR system (Thermo Fisher Scientific Inc., Waltham, MA, USA) [16][17][18][19][20][21][22]. One microliter of cDNA aliquots was added to each well.…”

“…The protein concentration was measured using a BCA Protein Assay Kit (Pierce Biotechnology, Rockford, IL, USA). Whole liver homogenates (25-50 μg protein in each lane) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) at a polyacrylamide gel concentration of 7.5-15% [14][15][16][17][18][19][20][21][22][23][24]. Nuclear fractions (21 μg of protein in each lane) were separated using 10% SDS-PAGE for assessing nuclear factor-kappa B (NF-κB) p65 component and peroxisome proliferator-activated receptor-α (PPARα).…”