Ceramide-mediated gut dysbiosis enhances cholesterol esterification and promotes colorectal tumorigenesis in mice
Yahui Zhu, Li Gu, Xi Lin, Jinmiao Zhang, Yi Tang, Xinyi Zhou, Bingjun Lu, Xingrong Lin, Cheng Liu, Edward V. Prochownik, Youjun Li
Yahui Zhu, Li Gu, Xi Lin, Jinmiao Zhang, Yi Tang, Xinyi Zhou, Bingjun Lu, Xingrong Lin, Cheng Liu, Edward V. Prochownik, Youjun Li
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Research Article Gastroenterology Metabolism

Ceramide-mediated gut dysbiosis enhances cholesterol esterification and promotes colorectal tumorigenesis in mice

Abstract

Colorectal cancer (CRC) severely threatens human health and life span. An effective therapeutic strategy has not been established because we do not clearly know its pathogenesis. Here, we report that ceramide and sterol O-acyltransferase 1 (SOAT1) have roles in both spontaneous and chemical-induced intestinal cancers. We first found that miRNA-148a deficiency dramatically increased mouse gut dysbiosis through upregulating ceramide synthase 5 (Cers5) expression, which promoted ceramide synthesis afterward. The newly generated ceramide further promoted both azoxymethane/dextran sodium sulfate–induced (AOM/DSS-induced) and ApcMin/+ spontaneous intestinal tumorigenesis via increasing mouse gut dysbiosis. Meanwhile, increased level of ceramide correlated with the significant enhancements of both β-catenin activity and colorectal tumorigenesis in a TLR4-dependent fashion. Next, we found a direct binding of β-catenin to SOAT1 promoter to activate transcriptional expression of SOAT1, which further induced cholesterol esterification and colorectal tumorigenesis. In human patients with CRC, the same CERS5/TLR4/β-catenin/SOAT1 axis was also found to be dysregulated. Finally, the SOAT1 inhibitor (avasimibe) showed significant levels of therapeutic effects on both AOM/DSS-induced and ApcMin/+ spontaneous intestinal cancer. Our study clarified that ceramide promoted CRC development through increasing gut dysbiosis, further resulting in the increase of cholesterol esterification in a SOAT1-dependent way. Treatment with avasimibe to specifically decrease cholesterol esterification could be considered as a clinical strategy for effective CRC therapy in a future study.

Authors

Yahui Zhu, Li Gu, Xi Lin, Jinmiao Zhang, Yi Tang, Xinyi Zhou, Bingjun Lu, Xingrong Lin, Cheng Liu, Edward V. Prochownik, Youjun Li

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Figure 2

Depletion of miR-148a upregulates CERS5 to increase colorectal carcinogenesis.

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Depletion of miR-148a upregulates CERS5 to increase colorectal carcinoge...
(A) Summary of bioinformatics screening results in CRCs. (B) qPCR analyses on the mRNA levels of Col4a1, Itga11, Cers5, Ltbp1, and Usp32 in WT and miR-148a–/– mice colon tissues (n = 5/group). (C) Western blot assay obtained the CERS5 protein levels in CRC from indicated mice (n = 3/group). (D) Reverse transcription qPCR (RT-qPCR) assay was performed to quantitate the targeted mRNAs of miR-148a-3p that incorporated into the RISC derived from colon tissues of either WT or miR-148a–/– mice. β-Actin was used as a control (n = 5/group). (E) Luciferase activity of the reporter vector containing WT or miR-148a-3p binding mutant 3′UTR of miR-148a-3p targets was determined in the HCT116 CRC cells transfected with indicated vectors. (F) CERS5 expression in normal colon and CRC tissues from TCGA data sets. (G) The colon C16:0 ceramide was detected by using mass spectrometry in WT mice and miR-148a–/– mice (n = 5/group). (H–J) Colon tumor numbers (H), average volumes, (I) and sizes (J) in indicated mice (n = 10–12/group). (K) The colon C16:1 ceramide was detected by using mass spectrometry in CRCs of indicated mice (n = 6/group). (L) qPCR analyses on the indicated microbiota in mice from H (n = 3/group). (M) The endotoxin concentrations in miR-148a–/– mice from H (n = 6/group). (Data were presented as mean ± SEM in B, D–K, and M.) *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Statistical significance was calculated by using 1-way ANOVA (E and H–K) or 2-tailed unpaired t test (B, D, F, G, and M). Data shown in E are representatives of 3 independent experiments. T/N, tumor/normal; FPKM, fragments per kilobase million; EU, endotoxin units.