The Deubiquitinating Enzyme Inhibitor PR-619 Enhances the Cytotoxicity of Cisplatin via the Suppression of Anti-Apoptotic Bcl-2 Protein: In Vitro and In Vivo Study.

Kuan-Lin Kuo,Kuo-How Huang,Yu-Wei Chang,Shing-Hwa Liu,Wei-Chou Lin,Hong-Chiang Chang,Chen-Hsun Hsu,Shao-Ping Yang,Shih-Ming Liao,Chung-Sheng Shi,Po-Ming Chow

doi:10.3390/cells8101268

Kuan-Lin Kuo, Kuo-How Huang + Show 9 more

Open Access

https://doi.org/10.3390/cells8101268

Copy DOI

Abstract

After chemotherapy for the treatment of metastatic bladder urothelial carcinoma (UC), most patients inevitably encounter drug resistance and resultant treatment failure. Deubiquitinating enzymes (DUBs) remove ubiquitin from target proteins and play a critical role in maintaining protein homeostasis. This study investigated the antitumor effect of PR-619, a DUBs inhibitor, in combination with cisplatin, for bladder UC treatment. Our results showed that PR-619 effectively induced dose- and time-dependent cytotoxicity, apoptosis, and ER-stress related apoptosis in human UC (T24 and BFTC-905) cells. Additionally, co-treatment of PR-619 with cisplatin potentiated cisplatin-induced cytotoxicity in UC cells and was accompanied by the concurrent suppression of Bcl-2. We also proved that Bcl-2 overexpression is related to the chemo-resistant status in patients with metastatic UC by immunohistochemistry (IHC) staining. In a xenograft mice model, we confirmed that PR-619 enhanced the antitumor effect of cisplatin on cisplatin-naïve and cisplatin-resistant UCs. Our results demonstrated that PR-619 effectively enhanced the cisplatin-induced antitumor effect via concurrent suppression of the Bcl-2 level. These findings provide promising insight for developing a therapeutic strategy for UC treatment.

Highlights

Bladder urothelial carcinoma (UC) is the sixth most common cancer in the United States, with approximately 80,470 predicted new cases in 2019 according to the American Cancer Society [1].Despite radical cystectomy, approximately 50% of cases of high-grade and muscle-invasive bladder UC progress to metastatic diseases
We found that PR-619 induced cytotoxicity in low-grade RT-4 UC cells and cisplatin-resistant UC cells (T24/R) in a dose- and time-dependent manner (Figures S1 and S2)
Our results show that PR-619 induced polyubiquitination, B-cell lymphoma-2 (Bcl-2) downregulation,6 of concurrent PARP cleavage in a dose-dependent manner (Figure 2A,B)

Summary

Introduction

Bladder urothelial carcinoma (UC) is the sixth most common cancer in the United States, with approximately 80,470 predicted new cases in 2019 according to the American Cancer Society [1]. Approximately 50% of cases of high-grade and muscle-invasive bladder UC progress to metastatic diseases. The mainstay of metastatic bladder UC treatment is cisplatin-based chemotherapy [2]. Chemotherapy provides an approximately 50% response rate, with a. 20% five-year survival rate [3,4]. Most patients experience relapse and resultant mortality due to drug. Cells 2019, 8, 1268 resistance [1]. Searching for novel strategies to circumvent chemoresistance to improve the outcomes of metastatic bladder cancer is imperative

Methods

Results

Conclusion