肿瘤细胞中YIPF2调控TNFRSF10B的分子机制

TRAIL receptors play critical role in the apoptosis induced by anti-cancer chemotherapeutic agents. It is known that TNFRSF10B is up-regulated by the transcriptional factor DDIT3 which is induced by ER stress. However, the mechanism underlying the plasma membrane trafficking of TNFRSF10B remains elusive. Our preliminary data show that YIPF2 is up-regulated in cancer cells after treatment with anti-cancer chemotherapeutic agents. Moreover, it has physical interaction with TNFRSF10B and enhances the trafficking of TNFRSF10B to the cell surface after treatment with anti-cancer drugs. In addition, YIPF2 can pull-down RAB8. And there are two putative XBP-1 binding sites in the YIPF2 promoter region. Therefore, we hypothesize that another transcriptional factor of ER stress XBP-1s promotes the expression of YIPF2 which recruits RAB8 to the membrane as a GDF. Consequently, YIPF2 and RAB8 accelerate the plasma membrane trafficking of TNFRSF10B and inhibit the ubiquitination and degradation of it, leading to apoptosis in cancer cells. Our goal is to identify the important factors involving in the regulation of TNFRSF10B at the post-translational level in apoptosis induced by the anti-cancer drugs. Eventually, this study will help us understand the apoptotic signaling in cancer cells and potentially facilitate anti-cancer drug discovery and development.

TRAIL受体在化疗药物诱导的肿瘤细胞凋亡过程中起着重要作用。化疗药物诱导的内质网应激通过DDIT3在转录水平上调TNFRSF10B表达，但TNFRSF10B在翻译后向质膜转运及维持稳定的机制尚不清楚。我们前期实验结果显示化疗药物诱导YIPF2水平上调，并与TNFRSF10B存在物理上的相互作用；YIPF2过表达可促进TNFRSF10B向质膜的转运，且RAB8可与YIPF2结合；YIPF2基因启动子区有两个潜在XBP-1结合位点。基于以上结果，提出假说：抗肿瘤药物诱导肿瘤细胞凋亡过程中，内质网应激激活的转录因子XBP-1s上调YIPF2表达，继而招募RAB8，增强TNFRSF10B向质膜转运，并抑制其泛素化和降解，促进TNFRSF10B诱导的细胞凋亡。我们的目的是探讨肿瘤细胞中TNFRSF10B在翻译后水平调控的分子机制，鉴定参与这一调控过程的重要蛋白，为研发抗肿瘤药物提供新思路。

非小细胞肺癌（Non-small cell lung cancer, NSCLC）是最常见的一种肺癌亚型，探讨其凋亡过程对治疗至关重要。TNF受体超家族成员TNFRSF10B的总体水平和细胞表面水平在化疗药物处理后都会增加，并且在这些药物诱导的细胞凋亡中起关键作用。然而，调控TNFRSF10B水平的确切分子机制仍不清楚。在本研究中，我们发现在非小细胞肺癌细胞中，化疗药物pemetrexed (PEM)处理后TNFRSF10B和一个囊泡转运调节蛋白YIPF2的水平都会增加。此外，过表达YIPF2增加了膜表面TNFRF10B的水平，敲低YIPF2抑制了TNFRSF10B的上调及其向质膜的循环。随后发现RAB8通过抑制细胞表面TNFRSF10B向质膜的转运降低其在细胞表面的水平。进一步，我们发现YIPF2、RAB8和TNFRSF10B蛋白之间存在物理上的相互作用。YIPF2可通过抑制TNFRSF10B与RAB8的相互作用，从而抑制RAB8对TNFRSF10B的回收和降解，最终维持TNFRSF10B在细胞表面的高水平，进而促进细胞凋亡。化疗药物激活内质网应激，导致XBP1S升高，从而上调YIPF2诱导细胞凋亡,YIPF2是XBP1S的靶蛋白。利用生物信息学数据库，我们发现YIPF2-TNFRSF10B轴与肺癌的恶性进展相关。综上所述，我们发现在非小细胞肺癌细胞中，化疗药物通过诱导内质网应激上调YIPF2表达，促进TNFRSF10B向质膜循环增多，从而促进化疗药物介导的细胞凋亡。我们的发现可能有助于了解肿瘤细胞凋亡诱导机制，鉴定非小细胞肺癌的潜在预后标志物，并提供有效的治疗策略。本项目资助下已发表5篇SCI论文，另有一篇在修回中，一篇在投稿准备中。本项目培养博士生4名、硕士研究生3名。