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Backgrounds: Triptolide (TP) exhibits effective activity against colon cancer in multiple preclinical models, but the mechanisms underlying the observed effects are not fully understood. Sphingosine-1-phosphate (S1P) is a potent bioactive sphingolipid involved in the regulation of colon cancer progression. The aim of this study was to investigate the effect of TP on the sphingosine kinase (SPHK)-S1P signaling pathway in colitis-associated colon cancer., Methods: An azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model and the THP-1 cell line were used to evaluate the therapeutic effects and mechanisms of TP in colitis-associated colon cancer (CACC). Various molecular cell biology experiments, including Western blotting, real-time PCR and immunofluorescence, were used to obtain relevant experimental data. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was also established to detect the levels of S1P in tissue and plasma., Results: In the AOM/DSS mouse model, TP treatment induced a dose-dependent decrease in tumor incidence and inhibited macrophage recruitment and M2 polarization in the tumors. TP also efficiently decreased the S1P levels and SPHK1/S1PR1/S1PR2 expression and significantly inhibited activation of the S1P-mediated phosphorylation of ERK protein in macrophages., Conclusions: The results indicated that TP might influence the recruitment and polarization of tumor-associated macrophages by suppressing the SPHK-S1P signaling pathway., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Inflammatory bowel disease is one of the major causes of colitis-associated colon cancer (CAC). Therefore, it is necessary to explore new therapies to prevent colon cancer (CRC) in view of the relationship between chronic inflammation and tumor development. Previous studies on the correlation between CD30L/CD30 and cancer were mostly limited to lymphoid or homogenous tumors, while there have been only a few reports on the role of CD30L/CD30 signal transduction in the pathogenesis of CAC. In this study, we established an AOM/DSS-induced CAC model with CD30LKO mice to explore the effect of CD30L/CD30 signal transduction on the formation of the intestinal tumor immune microenvironment (TIME) during the development of intestinal tumors. Our results revealed that CD30L deficiency promoted the accumulation of myeloid derived suppressor cells (MDSCs), increased the expression of PD-L1 on MDSCs and tumor associated macrophages (TAMs), and enhanced the secretion of various inflammatory and immunosuppressive factors in the intestinal mucosa of CAC mice. Furthermore, CD30L gene deletion could selectively promote the upregulation of PD-1 expression on CD4 + and CD8 + T cells and inhibit their activation, differentiation and secretion of effector cytokines, which led to an attenuation of antitumor immune responses mediated by T EM (CD44 + CD62L - ) cells. Thus, our data suggest that CD30L/CD30 signaling might be a potential candidate target for immunological therapy in CAC., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)