NANOG Metabolically Reprograms Tumor-Initiating Stem-like Cells through Tumorigenic Changes in Oxidative Phosphorylation and Fatty Acid Metabolism

Creators: Chen, Chia-Lin; Kumar, Dinesh Babu Uthaya; Punj, Vasu; Xu, Jun; Sher, Linda; Tahara, Stanley M.; Hess, Sonja; Machida, Keigo

Abstract

Stem cell markers, including NANOG, have been implicated in various cancers; however, the functional contribution of NANOG to cancer pathogenesis has remained unclear. Here, we show that NANOG is induced by Toll-like receptor 4 (TLR4) signaling via phosphorylation of E2F1 and that downregulation of Nanog slows down hepatocellular carcinoma (HCC) progression induced by alcohol western diet and hepatitis C virus protein in mice. NANOG ChIP-seq analyses reveal that NANOG regulates the expression of genes involved in mitochondrial metabolic pathways required to maintain tumor-initiating stem-like cells (TICs). NANOG represses mitochondrial oxidative phosphorylation (OXPHOS) genes, as well as ROS generation, and activates fatty acid oxidation (FAO) to support TIC self-renewal and drug resistance. Restoration of OXPHOS activity and inhibition of FAO renders TICs susceptible to a standard care chemotherapy drug for HCC, sorafenib. This study provides insights into the mechanisms of NANOG-mediated generation of TICs, tumorigenesis, and chemoresistance through reprogramming of mitochondrial metabolism.

Additional Information

© 2016 Elsevier Inc. Received: November 18, 2014; Revised: July 8, 2015; Accepted: November 23, 2015; Published: December 24, 2015. We thank Dr. Ratna Ray (Saint Louis University) for providing HCV NS5A Tg mice, Dr. Hidekazu Tsukamoto (USC) for valuable suggestions, Ms. Akiko Ueno and Mr. Raul Lazaro, the animal core personnel for performing mouse experiments, Dr. Bangyan Stiles, Dr. Tin A. Than and Mr. Chad Nakagawa (USC) for critical reading, Dr. Raymond Wu (USC) for suggestions and reagents, Dr. Todd L. Sladek (Rosalind Franklin University) for E2F1mutant constructs, and Dr. Carlo V. Catapano for PPARd expression constructs. Nanog luciferase reporter constructs were obtained from Dr. Paul Robson and Dr. Ng Huck Hui at the Genome Institute of Singapore and Dr. Takashi Tada at Kyoto University. Mouse strain [B6;129-Tg(CMV-EGFP,U6-shNanog)1Ttada] was obtained from RIKEN BioResource Center. This project was supported by NIH grants 1R01AA018857-01, pilot project funding (5P30DK048522-13), P50AA11999 (Research Project, Animal Core, Morphology Core, and Pilot Project Program), and R24AA012885 (Non-Parenchymal Liver Cell Core). This research is also supported by a Research Scholar Grant, RSG-12-177-01-MPC, and pilot funding (IRG-58-007-48) from the American Cancer Society. C.-L.C. is supported by CIRM grant (TG2-01161). Microscopy was performed by the Cell and Tissue Imaging Core of the USC Research Center for Liver Diseases (P30 DK048522). S.H. is supported by the Gordon and Betty Moore Foundation through grant GBMF775 and the Beckman Institute. Statistical analysis was performed by Dr. Susan Groshen and Ms. Lingyun Ji of the Norris Comprehensive Cancer Center Biostatistics Core supported by NIH/NCI P30 CA 014089. Animal imaging was performed by the USC Molecular Imaging Center supported by NIH/NVRR S10. Tissue pathological slide preparation was performed by Ms. Moli Chen and Mr. Denis Trana of the Norris Comprehensive Cancer Center Translational Pathology Core. The project described was supported in part by award number P30CA014089 (Histology Core in Norris Cancer Center) from the National Cancer Institute. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the NIH. Liver tissues were obtained from The Liver Tissue Cell Distribution System (LTCDS) at University of Minnesota. Author Contributions: K.M. and C.-L.C. conceived of the study. C.-L.C., K.M., D.B.U.K., J.X., S.H., and L.S. obtained the data. V.P. analyzed ChIP-seq, microarray, and proteomic data. S.H. conducted and analyzed the proteomics experiments. S.M.T. contributed to manuscript drafting and discussion. C.-L.C., K.M., and L.M. provided data management and provided statistical support. K.M. and C.-L.C. conducted the data analysis and drafted the report. All authors interpreted the data and contributed to the final version of this report.

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