Non-small cell lung cancer is the most common type of lung cancer, accounting for more than 80% of this tumor. Ubiquitin-specific protease (USP) 14 is one of the 100 deubiquitinating enzymes that is overexpressed in lung cancer and has been validated as a therapeutic target. The aim of this study is to determine whether the accumulation of ubiquitinated proteins results in endoplasmic reticulum (ER) stress-mediated autophagy. To inhibit USP-14, A549 lung cancer cells were treated with USP-14 siRNA and IU1-47 (20 μM). The protein level, mRNA expression, and cell cycle analysis were evaluated using Western blot, real-time PCR, and flow cytometry, respectively. We found that treating A549 cells with USP14 inhibitors significantly reduced the proliferation rate and induced cell cycle arrest at G2/M phase. We also found that USP14 inhibitors did not induce apoptosis but actually induced autophagy through accumulation of ubiquitinated proteins/ER stress/unfolded protein response (UPR) axis. Moreover, we have for the first time demonstrated that the USP14 inhibition induces ER stress–mediated autophagy in A549 cells by activation of c-Jun N-terminal kinase 1 (JNK1). In conclusion, the current investigation represents a new mechanism by which inhibition of USP14 triggers autophagy via ER stress–mediated UPR in A549 cells.

非小细胞肺癌是最常见的肺癌类型，占该类肿瘤的80%以上。泛素特异性蛋白酶 (USP) 14 是在肺癌中过度表达的 100 种去泛素化酶之一，已被验证为治疗靶点。本研究的目的是确定泛素化蛋白的积累是否会导致内质网 (ER) 应激介导的自噬。为了抑制 USP-14，用 USP-14 siRNA 和 IU1-47 (20 μM) 处理 A549 肺癌细胞。分别使用蛋白质印迹、实时PCR和流式细胞术评估蛋白质水平、mRNA表达和细胞周期分析。我们发现用 USP14 抑制剂处理 A549 细胞显着降低增殖率并诱导细胞周期停滞在 G2/M 期。我们还发现 USP14 抑制剂不会诱导细胞凋亡，但实际上通过泛素化蛋白/内质网应激/未折叠蛋白反应 (UPR) 轴的积累诱导自噬。此外，我们首次证明 USP14 抑制通过激活 c-Jun N 末端激酶 1 (JNK1) 诱导 A549 细胞中内质网应激介导的自噬。总之，当前的研究代表了一种新机制，通过抑制 USP14，可以通过 A549 细胞中内质网应激介导的 UPR 触发自噬。