Identification of a Nervous System Gene Expression Signature in Colon Cancer Stem Cells Reveals a Role for Neural Crest Regulators EGR2 and SOX2 in Tumorigenesis
Recent data support a hierarchical model of colon cancer driven by a population of cancer stem cells (CSCs). Greater understanding of the mechanisms that regulate CSCs may therefore lead to more effective treatments. Serial limiting dilution xenotransplantation assays of colon cancer patient-derived tumors demonstrated ALDHPositive cells to be enriched for tumorigenic self-renewing CSCs. In order to identify CSC modulators, we performed RNA-sequencing analysis of ALDHPositive CSCs from a panel of colon cancer patient-derived organoids (PDOs) and xenografts (PDXs). These studies demonstrated CSCs to be enriched for embryonic and neural development gene sets. Functional analyses of genes differentially expressed in both ALDHPositive PDO and PDX CSCs demonstrated the neural crest stem cell (NCSC) regulator and wound response gene EGR2 to be required for CSC tumorigenicity and to control expression of homeobox superfamily embryonic master transcriptional regulator HOX genes and the embryonic and neural stem cell regulator SOX2. In addition, we identify EGR2, HOXA2, HOXA4, HOXA5, HOXA7, HOXB2, HOXB3 and the tumor suppressor ATOH1 as new prognostic biomarkers in colorectal cancer.