Eukaryotic translation initiation factors (eIFs) are the key factors to synthesize translation initiation complexes during the synthesis of eukaryotic proteins. Besides, eIFs are especially important in regulating the immune function of tumor cells. However, the effect mechanism of eIFs in prostate cancer remains to be studied, which is precisely the purpose of this study. In this study, three groups of prostate cancer cells were investigated. One group had its eIF5B gene knocked down; another group had its Programmed death 1 (PD-L1) overexpressed; the final group had its Wild-type p53-induced gene 1 (Wig1) overexpressed. Genetic alterations of the cancer cells were performed by plasmid transfection. The expression of PD-L1 mRNA was detected by quantitative real-time PCR (qRT-PCR), and the expressions of PD-L1 and eIF5B proteins were observed by western blot assays. Cell Counting Kit-8 (CCK-8), flow cytometry, Transwell and Transwell martrigel were used to investigated cell proliferation, apoptosis, migration and invasion, respectively. The effect of peripheral blood mononuclear cells (PBMCs) on tumor cells was observed, and the interaction between eIF5B and Wig1 was revealed by co-immunoprecipitation (CoIP) assay. Finally, the effects of interference with eIF5B expression on the growth, morphology, and immunity of the tumor, as well as PD-L1 expression in the tumor, were verified by tumor xenograft assays in vivo. Compared with normal prostate epithelial cells, prostate cancer cells revealed higher expressions of eIF5B and PD-L1 interference with eIF-5B expression can inhibit the proliferation, migration, invasion and PD-L1 expression of prostate cancer cells. Meanwhile, the cancer cell group with interference with eIF5B expression also demonstrated greater, apoptosis and higher vulnerability to PBMCs. CoIP assays showed that Wig1 could bind to eIF5B in prostate cancer cells, and its overexpression can inhibit the proliferation, migration, invasion and PD-L1 expression of cancer cells while promoting apoptosis. Moreover, interference with eIF5B expression can inhibit tumor growth, destroy tumor morphology, and suppress the proliferation of tumor cells. eIF5B can promote the expression of PD-L1 by interacting with Wig1. Besides, interference with eIF5B expression can inhibit the proliferation, migration, invasion and immunosuppressive response of prostate cancer cells. This study proposes a new target, eIF5B, for immunotherapy of prostate cancer.

中文翻译：

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eIF5B 通过与 Wig1 相互作用调节前列腺癌细胞中 PD-L1 的表达

真核翻译起始因子（eIF）是真核蛋白质合成过程中合成翻译起始复合物的关键因素。此外，eIFs对于调节肿瘤细胞的免疫功能尤其重要。然而，eIFs在前列腺癌中的作用机制还有待研究，这也正是本研究的目的。在这项研究中，研究了三组前列腺癌细胞。一组的 eIF5B 基因被敲除；另一组的 eIF5B 基因被敲除。另一组的程序性死亡 1 (PD-L1) 过度表达；最后一组的野生型 p53 诱导基因 1 (Wig1) 过表达。通过质粒转染进行癌细胞的遗传改变。通过实时定量PCR（qRT-PCR）检测PD-L1 mRNA的表达，通过Western blot法观察PD-L1和eIF5B蛋白的表达。使用细胞计数试剂盒（CCK-8）、流式细胞仪、Transwell和Transwell martrigel分别研究细胞增殖、凋亡、迁移和侵袭。观察外周血单核细胞（PBMC）对肿瘤细胞的影响，并通过免疫共沉淀（CoIP）测定揭示eIF5B和Wig1之间的相互作用。最后，通过体内肿瘤异种移植实验验证了干扰eIF5B表达对肿瘤生长、形态和免疫以及肿瘤中PD-L1表达的影响。与正常前列腺上皮细胞相比，前列腺癌细胞中eIF5B和PD-L1的表达较高，干扰eIF-5B的表达可以抑制前列腺癌细胞的增殖、迁移、侵袭和PD-L1的表达。同时，干扰eIF5B表达的癌细胞组也表现出更大的凋亡和对PBMC的更高的脆弱性。CoIP检测显示，Wig1可以与前列腺癌细胞中的eIF5B结合，其过表达可以抑制癌细胞的增殖、迁移、侵袭和PD-L1表达，同时促进细胞凋亡。此外，干扰eIF5B表达可以抑制肿瘤生长，破坏肿瘤形态，抑制肿瘤细胞增殖。eIF5B可以通过与Wig1相互作用促进PD-L1的表达。此外，干扰eIF5B表达可以抑制前列腺癌细胞的增殖、迁移、侵袭和免疫抑制反应。这项研究提出了前列腺癌免疫治疗的新靶点 eIF5B。