前列腺癌(PCa)是美国男性癌症相关死亡的第二大原因。激素治疗后复发的PCa,称为抗去势PCA(CRPC),经常表现为转移瘤(mCRPC),这是死亡的主要原因。用于mCRPC患者的少数可用疗法包括紫杉烷类多西他赛(DTX)和卡巴他赛(CBZ)。然而,耐药性的发展限制了其临床应用。机械上,耐药性是通过多药耐药(MDR)蛋白如MDR1/ABCB1的上调而产生的,这使得ABCB1成为有吸引力的治疗靶点.然而,由于低特异性和毒性问题,ABCB1抑制剂未能在临床上有用。为了研究紫杉烷的抗性,我们产生了CBZ抗性C4-2B细胞(RC4-2B),并在细胞培养和3D前列腺球环境中记录了对CBZ和DTX的抗性.RNAseq鉴定了ABCB1在RC4-2B中的表达增加,免疫印迹和免疫荧光分析证实了这一点。ABCB1特异性抑制剂elacridar逆转RC4-2B细胞中的CBZ和DTX抗性,证实ABCB1介导的抗性机制。在使用细胞毒性药物精选库的基于细胞的筛选中,我们发现DNA损伤化合物喜树碱(CPT)和阿糖胞苷(Ara-C)克服了抗性,如在亲本C4-2B和抗性RC4-2B中相似的细胞毒性所见。Further,这些化合物对具有高ABCB1表达的紫杉烷抗性的多种PC细胞具有细胞毒性,因此,可用于征服PCa中紫杉烷的获得性抗性。最后,用小分子抑制剂(CDK4/6i)抑制细胞周期蛋白依赖性激酶4/6(CDK4/6)可增强亲本和抗性细胞中CPT或Ara-C的细胞毒性作用。总的来说,我们的发现表明,DNA损伤剂CPT和Ara-C单独或与CDK4/6i联合可作为CRPC患者的新治疗方案,包括那些抗紫杉烷的。
Prostate cancer (PCa) is the second leading cause of cancer-related death in American men. PCa that relapses after hormonal therapies, referred to as castration resistant PCa (CRPC), often presents with metastases (mCRPC) that are the major cause of mortality. The few available therapies for mCRPC patients include taxanes docetaxel (DTX) and cabazitaxel (CBZ). However, development of resistance limits their clinical use. Mechanistically, resistance arises through upregulation of multidrug resistance (MDR) proteins such as MDR1/ABCB1, making ABCB1 an attractive therapeutic target. Yet, ABCB1 inhibitors failed to be clinically useful due to low specificity and toxicity issues. To study taxanes resistance, we produced CBZ resistant C4-2B cells (RC4-2B) and documented resistance to both CBZ and DTX in cell culture and in 3D prostaspheres settings. RNAseq identified increased expression of ABCB1 in RC4-2B, that was confirmed by immunoblotting and immunofluorescent analysis. ABCB1-specific inhibitor elacridar reversed CBZ and DTX resistance in RC4-2B cells, confirming ABCB1-mediated resistance mechanism. In a cell-based screen using a curated library of cytotoxic drugs, we found that DNA damaging compounds Camptothecin (CPT) and Cytarabine (Ara-C) overcame resistance as seen by similar cytotoxicity in parental C4-2B and resistant RC4-2B. Further, these compounds were cytotoxic to multiple PC cells resistant to taxanes with high ABCB1 expression and, therefore, can be used to conquer the acquired resistance to taxanes in PCa. Finally, inhibition of cyclin-dependent kinases 4/6 (CDK4/6) with small molecule inhibitors (CDK4/6i) potentiated cytotoxic effect of CPT or Ara-C in both parental and resistant cells. Overall, our findings indicate that DNA damaging agents CPT and Ara-C alone or in combination with CDK4/6i can be suggested as a new treatment regimen in CRPC patients, including those that are resistant to taxanes.