miRNAs: A Promising Target in the Chemoresistance of Bladder Cancer

Zhonglin Cai,1,* Fa Zhang,2,* Weijie Chen,3,* Jianzhong Zhang,1 Hongjun Li1 1Department of Urology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, People’s Republic of China; 2Department of Urology, First Hospital of Lanzhou University, Lanzhou, Gansu, People’s Republic of China; 3Department of Urology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai Traditional Chinese Medicine University, Shanghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hongjun LiDepartment of Urology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, No. 1 Shuaifuyuan, Dongcheng District, Beijing 100730, People’s Republic of ChinaTel +86 139 0117 1724Email lihongjun@pumch.cnAbstract: Chemotherapy is an important cancer treatment method. Tumor chemotherapy resistance is one of the main factors leading to tumor progression. Like other malignancies, bladder cancer, especially muscle-invasive bladder cancer, is prone to chemotherapy resistance. Additionally, only approximately 50% of muscle-invasive bladder cancer responds to cisplatin-based chemotherapy. miRNAs are a class of small, endogenous, noncoding RNAs that regulate gene expression at the posttranscriptional level, which results in the inhibition of translation or the degradation of mRNA. In the study of miRNAs and cancer, including gastric cancer, prostate cancer, liver cancer, and colorectal cancer, it has been found that miRNAs can regulate the expression of genes related to tumor resistance, thereby promoting the progression of tumors. In bladder cancer, miRNAs are also closely related to chemotherapy resistance, suggesting that miRNAs can be a new therapeutic target for the chemotherapy resistance of bladder cancer. Therefore, understanding the mechanisms of miRNAs in the chemotherapy resistance of bladder cancer is an important foundation for restoring the chemotherapy sensitivity of bladder cancer and improving the efficacy of chemotherapy and patient survival. In this article, we review the role of miRNAs in the development of chemotherapy-resistant bladder cancer and the various resistance mechanisms that involve apoptosis, the cell cycle, epithelial-mesenchymal transition (EMT), and cancer stem cells (CSCs).Keywords: miRNAs, chemoresistant, bladder cancer, biomarkers, targeted therapy