目的:结直肠癌肿瘤进展和耐药的分子机制仍有待充分了解。最近的研究报道了一种名为白介素-4-诱导-1(IL4I1)的氨基酸氧化酶的促肿瘤发生作用。这里,我们探讨了IL4I1在结直肠癌中的作用和分子机制。
方法:我们采用了生物信息学分析和实验验证,通过使用临床样本和各种基于细胞的检测,包括westernblot,Transwell分析,患者来源的类器官培养,免疫荧光分析,T细胞毒性试验,和流式细胞术。
结果:生物信息学分析显示,IL4I1在结直肠癌组织中的表达高于正常组织。体外过表达IL4I1增强了细胞增殖,迁移,和大肠癌细胞的侵袭。此外,培养基中色氨酸(Trp)的剥夺降低了IL4I1的致癌作用。此外,我们在结直肠癌TCGA数据库中观察到IL4I1和AHR表达呈正相关.我们还检测到芳族烃受体(AHR)的细胞质表达和核易位增强。此外,IL4I1过表达抑制了肿瘤细胞的溶细胞杀伤并增强了T细胞耗竭。最后,在类器官培养模型中,我们发现,与单纯免疫疗法或SR-1治疗相比,免疫治疗和SR-1联合治疗可诱导更高水平的细胞凋亡.
结论:我们证明IL4I1通过依赖于AHR激活的色氨酸代谢促进结直肠癌进展和免疫抑制。
OBJECTIVE: The molecular mechanisms underlying tumor progression and drug resistance in colorectal cancer remain to be fully understood. Recent studies have reported a pro-tumorigenic role of an amino acid oxidase named interleukin-4-induced-1 (IL4I1). Here, we investigate the role and molecular mechanism of IL4I1 in colorectal cancer.
METHODS: We employed bioinformatics analysis and experimental validation by using clinical samples and a variety of cell-based assays, including western blot, Transwell assay, patient-derived organoid culture, Immunofluorescence assay, T cell cytotoxicity assay, and flow cytometry.
RESULTS: Bioinformatics analysis showed a higher IL4I1 expression in colorectal cancer tissues than in normal tissues. In vitro overexpression of IL4I1 enhanced the proliferation, migration, and invasion of colorectal cancer cells. In addition, deprivation of Tryptophan (Trp) in cultural medium diminished the oncogenic effect of IL4I1. Furthermore, we observed a positive correlation of IL4I1 and AHR expression in the TCGA database of colorectal cancer. We also detected an enhanced cytoplasmic expression and nuclear translocation of Aryl hydrocarbon receptor (AHR). Moreover, IL4I1 overexpression suppressed the cytolytic killing of tumor cells and enhanced T cell exhaustion. Finally, in the organoid culture model, we found that immunotherapy and SR-1 combination treatment could induce higher level of apoptosis than did the immunotherapy or SR-1 treatment alone.
CONCLUSIONS: we demonstrated that IL4I1 facilitated colorectal cancer progression and immunosuppression through tryptophan metabolism dependent on AHR activation.