Studies have suggested that dysregulation of peroxisomal lipid metabolism might play an important role in colorectal cancer (CRC) development. Here, we found that KrasG12D-driven CRC tumors demonstrate dysfunctional peroxisomal b-oxidation and identified Nudt7 (peroxisomal coenzyme A diphosphatase NUDT7) as one of responsible peroxisomal genes. In KrasG12D-driven CRC tumors, the expression level of Nudt7 was significantly decreased. Treatment of azoxymethane/dextran sulfate sodium (AOM/DSS) into Nudt7 knockout (Nudt7-/-) mice significantly induced lipid accumulation and the expression levels of CRC-related genes whereas xenografting of Nudt7-overexpressed LS-174T cells into mice significantly reduced lipid accumulation and the expression levels of CRC-related genes. Ingenuity pathway analysis of microarray using the colon of Nudt7-/- and Nudt7+/+ mice treated with AOM/DSS suggested Wnt signaling as one of activated signaling pathways in Nudt7-/- colons. Upregulated levels of β-catenin were observed in the colons of KrasG12D and AOM/DSS-treated Nudt7-/- mice and downstream targets of β-catenin such as Myc, Ccdn1, and Nos2, were also significantly increased in the colon of Nudt7-/- mice. We observed an increased level of palmitic acid in the colon of Nudt7-/- mice and attachment of palmitic acid-conjugated chitosan patch into the colon of mice induced the expression levels of b-catenin and CRC-related genes. Overall, our data reveal a novel role for peroxisomal NUDT7 in KrasG12D-driven CRC development.
Keywords: colorectal cancer; palmitic acid; peroxisomal coenzyme A diphosphatase NUDT7 (NUDT7); peroxisome; β-catenin.