LncPRF通过上调胰腺癌自身PD-1表达促进其转移的机制研究

It was reported that melanoma cell-intrinsic PD-1 promotes tumor growth in a non-immunedependent manner. However, the regulatory mechanism of tumor cell-intrinsic PD-1 expression and the effect of cell-intrinsic PD-1 on pancreatic cancer metastasis are still unclear. Our original results showed that ① cell-intrinsic PD-1 promotes PD-L1 induced-migration mediated by the activation of AKT and ERK pathway in pancreatic cancer cells. ② LncPRF is mainly expressed in the nucleus of pancreatic cancer cells, and the silence of LncPRF leads to down-regulation of Pax-5; ③ silencing the expression of Pax-5 suppressed the expression of PD-1. It is well-known that PD-1 inhibit immune cell activation through the recruitment of key molecules SHP2 in immune cells. On the contrary, ④ we found that SHP2 promote PD-L1 induced metastasis and the following activation of AKT/ERK pathway in pancreatic cancer cells. In this project, we aim to prove our hypothesis that LncPRF promote pancreatic cancer cells-intrinsic PD-1 expression by the upregulation of Pax-5, and PD-1 promote the metastasis by binding with SHP2 followed by the activation of AKT/ERK pathway in pancreatic cancer. This study would elucidate the role of tumor-intrinsic PD-1 in pancreatic cancer metastasis, and is benefit for the screening of adaptive patients for PD-1 targeting treatment.

文献报告，肿瘤细胞内源性PD-1可以非免疫依赖方式促进黑色素瘤生长。然而，肿瘤细胞自身PD-1的表达调控机制及其对转移的影响和机制尚不清楚。我们的原创性研究证明：①胰腺癌细胞自身表达PD-1，在PD-L1作用下，可激活AKT/ERK通路，促进胰腺癌转移；②LncPRF在细胞核中优势表达，沉默LncPRF后，Pax-5表达下调；③沉默Pax-5后，PD-1表达受抑。现已明确，免疫细胞中PD-1通过募集关键分子SHP2抑制免疫细胞活化。与此相反，我们的研究发现，④在胰腺癌细胞中SHP2促进了PD-L1诱导的胰腺癌细胞转移及AKT/ERK通路活化。本研究的目的是证明，在胰腺癌细胞中，LncPRF通过上调Pax-5转录，促进PD-1表达；PD-1与SHP2结合，激活AKT/ERK通路促进胰腺癌转移。本研究将为解明肿瘤细胞PD-1在肿瘤转移中的作用，更精确筛选靶向PD-1治疗的有效人群提供科学。

近年来对胰腺导管腺癌中的一些研究报道，包括lncRNA在内，对大多数功能性RNA在其中的功能都尚未阐释清楚。本项目基于前期发现胰腺导管腺癌细胞自身表达PD-1，沉默LncPRF后PD-1表达受抑，进一步研究证实了敲减LncPRF在体外及体内抑制胰腺癌细胞生长，敲减LncPRF使肿瘤相关经典通路的多个蛋白表达下降，其中纤连蛋白1（fibronectin 1，FN1）是细胞外基质（Extracellular matrix，ECM）相关蛋白，会通过ITGA/ITGB介导下游信号通路。回补FN1显著恢复了敲减lncPRF后的细胞增殖、凋亡和细胞迁移水平。提示敲减lncPRF通过降低FN1水平抑制胰腺癌细胞生长，同时抑制PD-1表达。本项目发现PD-1的下游蛋白SHP1靶向降低p-STAT3（Ser727）水平，抑制胰腺癌细胞增殖及迁移，同时抑制凋亡，提示SHP1在胰腺癌中作用机制复杂。通过我们的研究为胰腺癌中涉及SHP1的治疗提供了部分依据。通过对LncPRF在胰腺癌中的作用及机制研究，为胰腺癌治疗提供潜在干预靶点，具有重要的临床和科学价值。