Institute of Urology, The Third Affiliated Hospital of Shenzhen University (Luohu Hospital Group), Shenzhen 518000, China; Shenzhen Following Precision Medical Research Institute, Luohu Hospital Group, Shenzhen 518000, China.
Institute of Urology, The Third Affiliated Hospital of Shenzhen University (Luohu Hospital Group), Shenzhen 518000, China; Shenzhen Following Precision Medical Research Institute, Luohu Hospital Group, Shenzhen 518000, China; Medical Laboratory, The Third Affiliated Hospital of Shenzhen University (Luohu Hospital Group), Shenzhen 518000, China.
Biochem Pharmacol. 2021 Aug;190:114588. doi: 10.1016/j.bcp.2021.114588. Epub 2021 May 4.
Bladder cancer is one of the most common malignancy in the urinary tract with high recurrence and drug resistance in clinics. Alternative treatments from existing drugs might be a promising strategy. Nitazoxanide (NTZ), an FDA-approved antiprotozoal drug, has got increasingly noticed because of its favorable safety profile and antitumor potential, yet the effects in bladder cancer and underlying mechanisms remain poorly understood. Herein, we find that NTZ induces mitochondrial damage and mitophagy initiation through PINK1-generated phospho-ubiquitin(pS65-Ub) and autophagy receptor-mediated pathway even in the absence of Atg5/Beclin1. Meanwhile, NTZ inhibits lysosomal degradation activity, leading to mitophagy flux impairment at late stage. Mitochondrial reactive oxygen species (ROS) production is critical in this process, as eliminating ROS with N-acetylcysteine (NAC) efficiently inhibits PINK1 signaling-mediated mitophagy initiation and alleviates lysosomal dysfunction. Co-treatment with NTZ and autophagy inhibitor Chloroquine (CQ) to aggravate mitophagy flux impairment promotes NTZ-induced apoptosis, while alleviation of mitophagy flux impairment with ROS scavenger reduces cell death. Moreover, we also discover a similar signaling response in the 3D bladder tumor spheroid after NTZ exposure. In vivo study reveals a significant inhibition of orthotopic bladder tumors with no obvious systemic toxicity. Together, our results uncover the anti-tumor activities of NTZ with the involvement of ROS-mediated mitophagy modulation at different stages and demonstrate it as a potential drug candidate for fighting against bladder tumors.
膀胱癌是最常见的泌尿系统恶性肿瘤之一，临床上具有高复发和耐药性。从现有药物中寻找替代治疗方法可能是一种有前途的策略。硝唑尼特（NTZ）是一种获得美国食品和药物管理局（FDA）批准的抗寄生虫药物，由于其良好的安全性和抗肿瘤潜力，越来越受到关注，但在膀胱癌中的作用及其潜在机制仍知之甚少。在此，我们发现 NTZ 通过 PINK1 产生的磷酸泛素（pS65-Ub）和自噬受体介导的途径诱导线粒体损伤和自噬起始，即使在没有 Atg5/Beclin1 的情况下也是如此。同时，NTZ 抑制溶酶体降解活性，导致晚期自噬体通量受损。线粒体活性氧（ROS）的产生在这个过程中是至关重要的，因为用 N-乙酰半胱氨酸（NAC）消除 ROS 可以有效地抑制 PINK1 信号介导的自噬起始，并缓解溶酶体功能障碍。用 NTZ 和自噬抑制剂氯喹（CQ）联合处理以加重自噬体通量受损会促进 NTZ 诱导的细胞凋亡，而用 ROS 清除剂缓解自噬体通量受损则会减少细胞死亡。此外，我们还在 NTZ 暴露后的 3D 膀胱癌球体中发现了类似的信号反应。体内研究显示，NTZ 对原位膀胱癌有显著的抑制作用，且无明显的全身毒性。总之，我们的研究结果揭示了 NTZ 的抗肿瘤活性，涉及 ROS 介导的不同阶段的自噬体调节，并证明其作为对抗膀胱癌的潜在药物候选物。
