OASL promotes immune evasion in pancreatic ductal adenocarcinoma by enhancing autolysosome-mediated degradation of MHC-I

Xin Xing1,2*, Xia-Qing Li2*, Shi-Qi Yin2*, Hong-Tai Ma2*, Shu-Yu Xiao3, Aziguli Tulamaiti3, Yan Yang3, Shu-Heng Jiang3, Li-Peng Hu3, Zhi-Gang Zhang3, Yan-Miao Huo4, Dong-Xue Li3, Xiao-Mei Yang3, Xue-Li Zhang1,3

Abstract

Rationale: Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a global prevalence and poor prognosis, largely due to immune escape mechanisms. However, the potential reasons for the decreased infiltration of cytotoxic T lymphocytes (CTLs) in PDAC remain inadequately understood. In this study, we aimed to elucidate the molecular mechanisms contributing to the low-CTLs infiltration in patients with PDAC.

Methods: Bioinformatic analyses were used to identify key factors associated with low-CTLs infiltration in PDAC and the role of oligoadenylate synthetase-like (OASL) was mainly focused in our study. Immunohistochemistry (IHC) was used to assess the relationship between the expression of OASL and the prognosis of patients. Western blotting, Flow cytometry, Co-immunoprecipitation and Immunofluorescence were applied to elucidate the molecular mechanism by which OASL mediates immune escape in PDAC. The orthotopic PDAC models were constructed to evaluate the effects of OASL-knockdown on CD8+ T cells infiltration and tumor growth in vivo.

Results: OASL was found to be significantly upregulated in PDAC and negatively correlated with the major histocompatibility complex class I (MHC-I) expression, which is associated with worse patient prognosis. Notably, OASL-knockdown leads to a significant increase in CD8+ T cell infiltration and slows tumor growth in vivo. Mechanistic studies revealed that OASL -knockdown restored the total and surface MHC-I level through impairing neighbor of BRCA1 gene 1 (NBR1)-mediated autophagy-lysosomal degradation of MHC-I.

Conclusions: Targeting OASL enhances the immune response in PDAC, providing a novel therapeutic strategy to improve outcomes in PDAC patients.

文章详见：doi: 10.7150/thno.103494

在该研究中使用了圣尔生物一管式反转录试剂盒、SYBR Green qPCR Premix、BCA蛋白定量试剂盒等产品，用于RNA提取与实时荧光定量PCR实验和Western Blot实验。

RNA extraction and real-time quantitative polymerase chain reaction (RT-qPCR)

The first-strand cDNA was reverse-transcribed by the All-in-One First-Strand Synthesis Master Mix Reagent Kit (ShareBio, Shanghai, China). qRT-PCR was performed using SYBR green qPCR Premix (ShareBio, Shanghai, China)

Western blotting

Cell lysates were centrifuged at 4℃, 12000 rpm/min for 10 min, and the protein concentration was measured by a BCA kit (share-bio, SB-WB013).