Institute of Urology, Lanzhou University Second Hospital, Key Laboratory of Urological Diseases in Gansu Province, Gansu Nephro-Urological Clinical Center, Lanzhou, Gansu, 730030, China.
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
Free Radic Biol Med. 2023 Nov 1;208:587-601. doi: 10.1016/j.freeradbiomed.2023.09.017. Epub 2023 Sep 17.
Systemic therapy for muscle-invasive bladder cancer (BC) remains dominated by cisplatin-based chemotherapy. However, resistance to cisplatin therapy greatly limits long-term survival. Resistance to cisplatin-based chemotherapy still needs to be addressed. In this study, we established three cisplatin-resistant BC cell lines by multiple cisplatin pulse treatments. Interestingly, after exposure to cisplatin, all cisplatin-resistant cell lines showed lower reactive oxygen species (ROS) levels than the corresponding parental cell lines. Using proteomic analysis, we identified 35 proteins that were upregulated in cisplatin-resistant BC cells. By knocking down eleven of these genes, we found that after CAB39 knockdown, BC cisplatin-resistant cells were more sensitive to cisplatin. Overexpression of CAB39 had the opposite effect. Then, the knockdown of six genes downstream of CAB39 revealed that CAB39 promoted cisplatin resistance in BC through LKB1. Moreover, a key cause of cisplatin-induced cell death is damage to mitochondria and increased ROS levels. In our study, cisplatin-resistant cells exhibited higher autophagic flux and healthier mitochondrial status after cisplatin exposure. We demonstrated that the CAB39-LKB1-AMPK-LC3 pathway plays a critical role in enhancing autophagy to maintain the health of mitochondria and reduce ROS levels. In addition, the autophagy inhibitor chloroquine (CQ) can significantly enhance the killing effect of cisplatin on BC cells. Compared with gemcitabine plus cisplatin (GC), GC plus CQ significantly reduced tumor burden in vivo. In conclusion, our study shows that CAB39 counteracts the killing of cisplatin by enhancing the autophagy of BC cells to damaged mitochondria and other organelles to alleviate the damage of cells caused by harmful substances such as ROS.
肌层浸润性膀胱癌（BC）的全身治疗仍然以顺铂为基础的化疗为主。然而，对顺铂治疗的耐药性极大地限制了长期生存。仍然需要解决对顺铂为基础的化疗的耐药性。在这项研究中，我们通过多次顺铂脉冲处理建立了三个顺铂耐药的 BC 细胞系。有趣的是，在暴露于顺铂后，所有顺铂耐药的细胞系的活性氧（ROS）水平均低于相应的亲本细胞系。通过蛋白质组学分析，我们鉴定了在顺铂耐药 BC 细胞中上调的 35 种蛋白质。通过敲低其中的 11 种基因，我们发现 CAB39 敲低后，BC 顺铂耐药细胞对顺铂更敏感。CAB39 的过表达则有相反的效果。然后，敲低 CAB39 下游的六个基因表明，CAB39 通过 LKB1 促进 BC 中的顺铂耐药性。此外，顺铂诱导细胞死亡的一个关键原因是线粒体损伤和 ROS 水平升高。在我们的研究中，顺铂耐药细胞在暴露于顺铂后表现出更高的自噬通量和更健康的线粒体状态。我们证明，CAB39-LKB1-AMPK-LC3 途径在增强自噬以维持线粒体健康和降低 ROS 水平方面发挥着关键作用。此外，自噬抑制剂氯喹（CQ）可以显著增强顺铂对 BC 细胞的杀伤作用。与吉西他滨加顺铂（GC）相比，GC 加 CQ 显著降低了体内肿瘤负担。总之，我们的研究表明，CAB39 通过增强 BC 细胞对受损线粒体和其他细胞器的自噬作用来抵消顺铂的杀伤作用，从而减轻 ROS 等有害物质对细胞造成的损害。
