Abstract 96: High iron or high fat diet show similar effects in inducing hepatocellular carcinoma in a mouse model

Abstract

Introduction: Hepatocellular carcinoma (HCC) has multiple risk factors such as Hepatitis virus infection and obesity. Iron overload may be another risk factor as patients with hemochromatosis have high levels of liver iron accumulation and higher incidence of HCC than the general population. This study aims to assess the risk of high iron diet in comparison to high fat diet in the development of HCC. Materials & Methods: We used C3HeB/FeJ male mice, which have been shown to spontaneously develop HCC. Two-month old mice were fed for 15 months with a control diet (10 kcal% from fat; 48 ppm Iron), high iron diet (HID) (10 kcal% from fat; 200 ppm Iron), high fat diet (HFD) (61.1 kcal% from fat; 48 ppm Iron), or high iron and fat diet (HIFD) (61.1 kcal% from fat; 200 ppm Iron). The presence of liver tumor was confirmed by ultrasound imaging and histology analysis. At termination, normal and tumor liver tissues were harvested for tumor size measurement, metal ion quantification, immunohistochemistry, and gene expression with RNA-seq. Results: HID like HFD induced significant body weight gain. All three diets induced HCC (4 out of 7 by HID, 7 out of 9 by HFD, and 8 out of 10 by HIFD). Yet, HCC was not found in the control diet group. The three diets showed no significantly different effects on tumor burden and grade. The concentrations of iron and copper were increased in the normal liver tissues of HID and HIFD groups. Interestingly, they were significantly lower in the tumor tissues than in the paired adjacent non-tumor tissues. Analyses of RNA-seq data revealed extensive overlap of tumor-specific differentially expressed genes (DEGs) among the three diet groups. The extensive overlap was also observed in the DEG-associated gene otology (GO) terms among the three diet groups. All three diets, but not the control diet, were shown to activate mTORC1 pathway in the tumors according to our RNA-seq data. The activation of mTORC1 pathway in the three diet-induced tumors was also confirmed with Real-time RT-PCR assays revealing upregulation of mTORC1 target genes and with immunohistochemistry showing increased phosphorylation of an mTORC1 substrate. Conclusions: The spontaneous hepatocarcinogenesis in male C3HeB/FeJ mice requires HID or HFD. The lack of additive effect of HID and HFD on HCC incidence and the extensive overlap of DEGs and GO terms among tumors induced by HID and HFD suggest they may regulate common mechanisms such as mTORC1 in inducing HCC. Citation Format: Hakim Bouamar, Kalyan Kakarla, Matyas Cserhati, Fatima Ezzahra El Mroussi, Francis E Sharkey, Francisco Cigarroa, Lu-Zhe Sun. High iron or high fat diet show similar effects in inducing hepatocellular carcinoma in a mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 96.