Exploiting oxidative phosphorylation to promote the stem and immunoevasive properties of pancreatic cancer stem cells

© The Author(s) 2020
Pancreatic ductal adenocarcinoma (PDAC), the fourth leading cause of cancer death, has a 5-year survival rate of approximately 7–9%. The ineffectiveness of anti-PDAC therapies is believed to be due to the existence of a subpopulation of tumor cells known as cancer stem cells (CSCs), which are functionally plastic, and have exclusive tumorigenic, chemoresistant and metastatic capacities. Herein, we describe a 2D in vitro system for long-term enrichment of pancreatic CSCs that is amenable to biological and CSC-specific studies. By changing the carbon source from glucose to galactose in vitro, we force PDAC cells to utilize OXPHOS, resulting in enrichment of CSCs defined by increased CSC biomarker and pluripotency gene expression, greater tumorigenic potential, induced but reversible quiescence, increased OXPHOS activity, enhanced invasiveness, and upregulated immune evasion properties. This CSC enrichment method can facilitate the discovery of new CSC-specific hallmarks for future development into targets for PDAC-based therapies.
We acknowledge and thank Dr. Nuria Malats and Jaime Villarreal from the Spanish National Cancer Research Center (CNIO) for RNA sequencing and analysis, funded by Fondo de Investigaciones Sanitarias (FIS) grant PI18/01347. We thank Patricia Sánchez-Tomero and Marina Ochando-Garmendia for technical assistance and support and Dr. Raúl Sánchez Lanzas for assistance with autophagy experiments. We want to particularly acknowledge the patients and the BioBank Hospital Ramón y Cajal-IRYCIS (PT13/0010/0002) integrated in the Spanish National Biobanks Network for its collaboration and, in particular, Adrián Povo Retana for macrophage isolation. We would also like to thank the Transmission Electron Microscopy Unit Laboratory, part of the UAM Interdepartmental Investigation Service (SIdI); Coral Pedrero for exceptional help with in vivo experiments; and the laboratories of Dr. Amparo Cano and Dr. José González Castaño for reagents and helpful discussions. S.V. was a recipient of an Ayuda de Movilidad del Personal Investigador del IRYCIS, a mobility grant from the Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain, and a pre-doctoral fellowship from the Comunidad de Madrid, Ayudas Para La Contratación De Investigadores Predoctorales Y Posdoctorales (PEJD-2017-PRE/BMD-5062), Madrid, Spain. This study was supported by a Rámon y Cajal Merit Award (RYC-2012-12104) from the Ministerio de Economía y Competitividad, Spain (to B.S.); funding from la Beca Carmen Delgado/Miguel Pérez-Mateo from AESPANC-ACANPAN Spain (to B.S.); a Conquer Cancer Now Grant from the Concern Foundation (Los Angeles, CA, USA) (to B.S.); a Coordinated grant (GC16173694BARB) from the Fundación Asociación Española Contra el Cáncer (AECC) (to B.S.); FIS grants PI18/00757 (to B.S.), PI16/00789 (to M.A.F.-M.), PI18/00267 (to L.G.-B.; co-financed through Fondo Europeo de Desarrollo Regional (FEDER) “Una manera de hacer Europa”); a Miguel Servet award (CP16/00121) (to P.S.); a Max Eder Fellowship of the German Cancer Aid (111746) (to P.C.H.); and the German Research Foundation (DFG, CRC 1279 “Exploiting the human peptidome for Novel Antimicrobial and Anticancer Agents”; to P.C.H.).