Department of Urologic Surgery, University of California, Davis, Davis, California.
UC Davis Comprehensive Cancer Center, University of California, Davis, Davis, California.
Mol Cancer Ther. 2019 Oct;18(10):1875-1886. doi: 10.1158/1535-7163.MCT-18-1322. Epub 2019 Jul 15.
The mechanisms resulting in resistance to next-generation antiandrogens in castration-resistant prostate cancer are incompletely understood. Numerous studies have determined that constitutively active androgen receptor (AR) signaling or full-length AR bypass mechanisms may contribute to the resistance. Previous studies established that AKR1C3 and AR-V7 play important roles in enzalutamide and abiraterone resistance. In the present study, we found that AKR1C3 increases AR-V7 expression in resistant prostate cancer cells through enhancing protein stability via activation of the ubiquitin-mediated proteasome pathway. AKR1C3 reprograms AR signaling in enzalutamide-resistant prostate cancer cells. In addition, bioinformatical analysis of indomethacin-treated resistant cells revealed that indomethacin significantly activates the unfolded protein response, p53, and apoptosis pathways, and suppresses cell-cycle, Myc, and AR/ARV7 pathways. Targeting AKR1C3 with indomethacin significantly decreases AR/AR-V7 protein expression and through activation of the ubiquitin-mediated proteasome pathway. Our results suggest that the AKR1C3/AR-V7 complex collaboratively confers resistance to AR-targeted therapies in advanced prostate cancer.
雄激素受体信号通路在前列腺癌的发生、发展中起着关键作用,雄激素受体(androgen receptor,AR)信号通路的激活是前列腺癌发生和发展的重要机制。去势抵抗性前列腺癌(castration-resistant prostate cancer,CRPC)是前列腺癌发展的终末阶段,也是前列腺癌患者死亡的主要原因。目前,CRPC 的治疗主要包括内分泌治疗、化疗、放疗等。AR 信号通路的激活是 CRPC 发生和发展的重要机制之一,因此,抑制 AR 信号通路的激活可以有效地治疗 CRPC。
恩杂鲁胺(enzalutamide)和阿比特龙(abiraterone)是两种新型的 AR 靶向药物,它们可以有效地抑制 AR 信号通路的激活,从而抑制前列腺癌细胞的生长和增殖。然而,随着治疗的进行,CRPC 患者会出现耐药性,导致治疗失败。因此,研究 AR 信号通路的耐药机制对于开发新的治疗策略具有重要意义。
AKR1C3 是一种细胞色素 P450 酶,它可以将雄激素转化为更具活性的代谢产物。先前的研究表明,AKR1C3 在前列腺癌中高表达,并且与前列腺癌的发生、发展和预后密切相关。AKR1C3 可以通过激活 AR 信号通路促进前列腺癌细胞的生长和增殖,从而促进前列腺癌的发生和发展。
AR-V7 是 AR 的一种剪接变体,它可以逃避恩杂鲁胺和阿比特龙的抑制作用,从而导致耐药性的产生。先前的研究表明,AR-V7 在 CRPC 中高表达,并且与前列腺癌的耐药性密切相关。AKR1C3 可以通过激活 AR 信号通路促进 AR-V7 的表达,从而导致耐药性的产生。
在本研究中,我们发现 AKR1C3 通过激活泛素-蛋白酶体途径增强蛋白稳定性,从而增加耐药性前列腺癌细胞中 AR-V7 的表达。AKR1C3 重编程恩杂鲁胺耐药性前列腺癌细胞中的 AR 信号。此外,生物信息学分析表明,吲哚美辛处理耐药细胞后,细胞未折叠蛋白反应、p53 和细胞凋亡途径被显著激活,细胞周期、Myc 和 AR/AR-V7 途径被显著抑制。通过激活泛素-蛋白酶体途径,吲哚美辛靶向 AKR1C3 可显著降低 AR/AR-V7 蛋白表达。我们的研究结果表明,AKR1C3/AR-V7 复合物协同赋予晚期前列腺癌对 AR 靶向治疗的耐药性。