Tanreqing suppresses the proliferation and migration of non-small cell lung cancer cells by mediating the inactivation of the HIF1α signaling pathway via exosomal circ-WDR78

Circular RNAs (circRNAs) have emerged as regulators of cancer progression, including non-small cell lung cancer (NSCLC). Tanreqing (TRQ), a traditional Chinese medicine, is used clinically for respiratory diseases. RT-qPCR quantified circ-WDR78 expression in NSCLC cells. Cell growth, apoptosis, invasion, and migration were assessed by functional assays. RNA-binding protein immunoprecipitation (RIP), luciferase reporter, and RNA pull-down assays determined the competing endogenous RNA (ceRNA) network of circ-WDR78. The interaction between HIF1α and CD274 (PD-L1) promoter was analyzed by chromatin immunoprecipitation (ChIP). Circ-WDR78 expression was up-regulated in TRQ-treated NSCLC cells. Functionally, circ-WDR78 exhibited anti-tumor effects in these cells. Additionally, circ-WDR78 could also induce reactive oxygen species (ROS) accumulation by down-regulating HIF1α expression, promoting autophagy. Mechanistically, circ-WDR78 destabilizes HIF1α <i>via</i> the miR-1265/FBXW8 axis. TRQ-induced exosome secretion from NSCLC cells inhibits PD-L1 expression, preventing immune escape. We found that TRQ-treated NSCLC cells secrete exosomes to transmit circ-WDR78 to untreated NSCLC cells, inhibiting the malignancy of recipient tumor cells. In conclusion, TRQ inhibits NSCLC cell proliferation, invasion, and migration through exosomal circ-WDR78-mediated inactivation of the HIF1α signaling pathway, providing potential insight into TRQ injection for NSCLC treatment.

环状RNA（circular RNAs, circRNAs）已被证实可调控包括非小细胞肺癌（non-small cell lung cancer, NSCLC）在内的多种癌症的进展。痰热清（Tanreqing, TRQ）是一种临床常用于治疗呼吸系统疾病的传统中药。本研究通过实时定量聚合酶链反应（RT-qPCR）检测非小细胞肺癌细胞中circ-WDR78的表达水平，采用功能实验评估细胞增殖、凋亡、侵袭及迁移能力；通过RNA结合蛋白免疫沉淀（RNA-binding protein immunoprecipitation, RIP）、荧光素酶报告基因实验及RNA下拉实验，解析circ-WDR78的内源竞争RNA（competing endogenous RNA, ceRNA）调控网络；通过染色质免疫沉淀（chromatin immunoprecipitation, ChIP）分析缺氧诱导因子1α（HIF1α）与CD274（程序性死亡受体配体1, PD-L1）启动子的相互作用。实验结果显示，经TRQ处理的非小细胞肺癌细胞中circ-WDR78的表达显著上调；功能层面，circ-WDR78在这些细胞中发挥抗肿瘤效应。此外，circ-WDR78还可通过下调HIF1α的表达诱导活性氧（reactive oxygen species, ROS）积累，进而促进细胞自噬（autophagy）；机制上，circ-WDR78通过微小RNA-1265（miR-1265）/F-box/WD重复蛋白8（FBXW8）轴调控HIF1α的稳定性。TRQ诱导非小细胞肺癌细胞分泌的外泌体（exosome）可抑制PD-L1的表达，从而阻断肿瘤免疫逃逸（immune escape）；进一步研究发现，经TRQ处理的非小细胞肺癌细胞可通过分泌外泌体将circ-WDR78传递至未处理的非小细胞肺癌细胞，抑制受体肿瘤细胞的恶性表型。综上，TRQ可通过外泌体包裹的circ-WDR78介导的HIF1α信号通路失活，抑制非小细胞肺癌细胞的增殖、侵袭与迁移，为TRQ注射液用于非小细胞肺癌的临床治疗提供了潜在的理论依据。