去泛素化酶PR-619可反轉對順鉑具抗藥性的尿路上皮癌細胞之抗藥性

許富順、郭冠麟¹、黃國皓¹

台北市立聯合醫院陽明院區 泌尿科；¹台大醫院 泌尿部

PR-619, an inhibitor of deubiquitylating enzymes, reverses drug resistance in cisplatin-resistant urothelial carcinoma cells via suppression of c-myc

Fu-Shun Hsu, Kuan-Lin Kuo¹, Kuo-How Huang¹

Department of Urology, Yangming Branch, Taipei City Hospital, Taipei, Taiwan;

Department of Urology, National Taiwan University Hospital, Taipei, Taiwan¹

Purpose:

As a pan-DUB inhibitor, PR-619 has a broad specificity that inhibits multiple DUBs and has been reported to be effective in the treatment of some cancers. Ｗe conducted in vitro and in vivo experiments to investigate the efficacy of PR-619 in inhibiting human cisplatin-sensitive and cisplatin-resistant UC cells.

Materials and Methods:

Cisplatin-resistant UC cells (T24/R) were derived from the original parental T24 cell line through continuous exposure to the half-maximal inhibitory concentration (IC50) of cisplatin for 72 h. Cytotoxicity and apoptosis were assessed using fluorescence-activated cell sorting, flow cytometry, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium assay. Immunohistochemical staining of USP21 demonstrated that deubiquitination is related to chemoresistance status in metastatic UC patients and may be a target to overcome chemoresistance.

Results:

Cisplatin-resistant UC cells exhibited upregulated levels of the antiapoptotic factor c-myc, and siRNA-mediated c-myc knockdown resensitized cisplatin-induced cytotoxicty. PR-619 enhanced the cytotoxic and apoptotic effects of cisplatin in cisplatin-resistant T24/R cells. The alleviation of cisplatin chemoresistance was associated with concurrent suppression of c-myc in T24/R cells. Moreover, the xenograft nude mouse model confirmed that PR-619 enhanced the antitumor effects of cisplatin. Therefore, the addition of PR-619 may circumvent chemoresistance by downregulating c-myc. These findings provide promising insights for the development of therapeutic strategies to circumvent chemoresistance in UCs by combining chemotherapeutic agents with deubiquitination inhibitor (PR-619) or by targeting the c-myc pathway.

Conclusions:

Our results indicated that the combination of cisplatin and PR-619 was synergistic, as the addition of PR-619 significantly improved the efficacy of cisplatin. The in vivo result indicates that the therapeutic efficacy was significantly improved by the combined treatment compared to that of cisplatin alone.