BACKGROUND Tripartite motif-containing proteins (TRIM) play a crucial role in carcinogenesis. Little attention has been focused on the possible functions of TRIM6 on carcinogenesis. METHODS The expression levels of TRIM6 were assessed in colorectal cancer (CRC) samples. TRIM6 expression was knocked down in CRC cell lines, and subjected to Cell counting kit-8 (CCK-8), bromodeoxyuridine (BrdU) incorporation and cell cycle assays. Immunoprecipitation and proteomics analysis was performed to identify potential associated proteins of TRIM6. RESULTS TRIM6 expression was up-regulated in CRC samples and TRIM6 expression may be an independent prognostic marker for CRC. Knocking down TRIM6 expression suppressed CRC cell proliferation, induced cell cycle arrested at G2/M phase and increased sensitivity to 5-fluorouracil and oxaliplatin. TIS21, an anti-proliferative protein involved in the regulation of G2/M arrest, was identified as an interaction partner of TRIM6. Moreover, CRC cells with TRIM6 overexpression showed decreased TIS21 protein stability. TIS21 ubiquitination was increased in CRC cells overexpressing TRIM6, but not in those overexpressing TRIM6 E3 catalytic mutant (C15A). Further, Lys5 was essential for TRIM6 mediated TIS21 ubiquitination. TIS21 overexpression reversed the induced effects of TRIM6 overexpression on CRC cell proliferation, and the levels of forkhead box M1 (FoxM1), phosphorylated FoxM1, Cyclin B1 and c-Myc. Thiostrepton, a specific inhibitor for FoxM1, was less effective in anti-proliferative activity against CRC cells with lower level of TRIM6 in vitro and in vivo. CONCLUSIONS Our study suggests that TRIM6 promotes the progression of CRC via TIS21/FoxM1.

中文翻译：

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TRIM6 通过 TIS21/FoxM1 促进结直肠癌细胞增殖和对硫链丝菌肽的反应。

背景技术含三部分基序的蛋白质（TRIM）在致癌作用中起关键作用。很少有人关注 TRIM6 在致癌作用中的可能功能。方法 在结直肠癌 (CRC) 样本中评估 TRIM6 的表达水平。TRIM6 表达在 CRC 细胞系中被敲低，并进行细胞计数试剂盒 8 (CCK-8)、溴脱氧尿苷 (BrdU) 掺入和细胞周期测定。进行免疫沉淀和蛋白质组学分析以鉴定TRIM6的潜在相关蛋白。结果 TRIM6 表达在 CRC 样本中上调，TRIM6 表达可能是 CRC 的独立预后标志物。敲除 TRIM6 表达可抑制 CRC 细胞增殖，诱导细胞周期停滞在 G2/M 期，并增加对 5-氟尿嘧啶和奥沙利铂的敏感性。TIS21, 一种参与调节 G2/M 阻滞的抗增殖蛋白，被鉴定为 TRIM6 的相互作用伙伴。此外，TRIM6过表达的CRC细胞显示TIS21蛋白稳定性降低。TIS21 泛素化在过度表达 TRIM6 的 CRC 细胞中增加，但在过度表达 TRIM6 E3 催化突变体 (C15A) 的那些细胞中则没有。此外，Lys5 对 TRIM6 介导的 TIS21 泛素化至关重要。TIS21 过表达逆转了 TRIM6 过表达对 CRC 细胞增殖和叉头盒 M1 (FoxM1)、磷酸化 FoxM1、Cyclin B1 和 c-Myc 水平的诱导作用。FoxM1 的特异性抑制剂 Thiostrepton 在体外和体内对 TRIM6 水平较低的 CRC 细胞的抗增殖活性较差。结论 我们的研究表明，TRIM6 通过 TIS21/FoxM1 促进 CRC 的进展。