Hypoxia promotes immune escape of pancreatic cancer cells by lncRNA NNT-AS1/METTL3-HuR-mediated ITGB1 m6A modification.

ABSTRACT

Pancreatic cancer (PC) cell immune escape is a crucial element in PC malignant development. Some previous studies have reported that LncRNA NNT-AS1 played a carcinogenic role in various tumors. However, the effect of lncRNA NNT-AS1 in PC cell immune escape remains unclear. To evaluate PC cell immune escape, PC cells were co-cultured with CD8+ T cells under a hypoxic condition. PC cell proliferation and migration were evaluated using the colony formation assay and transwell assay. CD8+ T cell proliferation and aoptosis were measured using the carboxy fluorescein diacetate succinimidyl ester (CFSE) assay and flow cytometry. The secretion of antitumor cytokines was assessed using enzyme-linked immunosorbent assay (ELISA). The molecular interactions were analyzed using chromatin immunoprecipitation (ChIP), RNA immunoprecipitation (RIP), or dual-luciferase reporter gene assays. A tumor xenograft model was established to evaluate the effects of lncRNA NNT-AS1 on PC in vivo. It was found that lncRNA NNT-AS1 was highly expressed in PC, and its silencing inhibited hypoxia-induced PC cell growth and immune escape in vivo and in vitro. Mechanically, HIF-1α transcriptionally activated NNT-AS1 expression and NNT-AS1 increased ITGB1 stability and expression in a METTL3-HuR dependent manner. ITGB1 overexpression reversed the inhibitory effects of NNT-AS1 knockdown on hypoxia-induced PC cell immune escape. In conclusion, Hypoxia promoted PC cell immune escape through lncRNA NNT-AS1/METTL3-HuR-mediated m6A modification to increase ITGB1 expression, which provided a theoretical foundation and a potential therapeutic target for PC.