Knockdown of TRIM9 attenuates irinotecan‑induced intestinal mucositis in IEC‑6 cells by regulating DUSP6 expression via the P38 pathway.

Intestinal mucositis is a common side effect of cancer chemotherapy and it limits the dose of chemotherapy given to a patient. Tripartite motif family (TRIM) proteins have been reported to be implicated in the regulation of cancer chemotherapy. The present study aimed to investigate the effect of TRIM9 on irinotecan‑induced intestinal mucositis in the rat intestinal epithelial cell line IEC‑6. The expression of several TRIMs, such as TRIM1, TRIM9, TRIM18, TRIM36, TRIM46 and TRIM67, was examined. After TRIM9 knockdown or overexpression by lentivirus infection, cell proliferation and apoptosis, epithelial barrier tight‑junction proteins, inflammatory cytokines, transepithelial electrical resistance (TEER) and FITC dextran were measured. Treatment with irinotecan significantly inhibited cell proliferation and induced cell apoptosis, TRIM9 expression, intestinal mucosal barrier impairment, the levels of inflammatory cytokines and P38 phosphorylation in IEC‑6 cells, while the expression levels of epithelial barrier tight‑junction protein ZO‑1 and Claudin‑4 were decreased. Knockdown of TRIM9 partly counteracted the effect of irinotecan treatment, and inhibition of P38 potently reversed the effect of TRIM9 overexpression in IEC‑6 cells. Moreover, co‑immunoprecipitation showed an interaction between TRIM9 and DUSP6 in IEC‑6 cells, and overexpression of DUSP6 notably counteracted the effect of TRIM9 overexpression. The results demonstrated that TRIM9 knockdown may benefit patients with intestinal mucositis by inhibiting inflammatory cytokine expression and repairing intestinal barrier functions, which was probably due to inhibition of the activation of the P38 pathway via targeting DUSP6.