Ishov Alexander, Sarwar Sadia, Morozov Viacheslav, Newcomb Mallory, Guryanova Olga
University of Florida College of Medicine.
Res Sq. 2024 Apr 29:rs.3.rs-4238716. doi: 10.21203/rs.3.rs-4238716/v1.
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 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 FDA-approved 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 CDK4/6 kinases 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.
前列腺癌（PCa）是美国男性癌症相关死亡的第二大主要原因。激素治疗后复发的PCa，即去势抵抗性PCa（CRPC），通常会出现转移（mCRPC），这是死亡的主要原因。mCRPC患者可用的治疗方法很少，包括紫杉烷类药物多西他赛（DTX）和卡巴他赛（CBZ）。然而，耐药性的产生限制了它们的临床应用。从机制上讲，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成为一个有吸引力的治疗靶点。然而，由于特异性低和毒性问题，ABCB1抑制剂未能在临床上发挥作用。为了研究紫杉烷类药物的耐药性，我们制备了对CBZ耐药的C4-2B细胞（RC4-2B），并在细胞培养和三维前列腺球模型中记录了对CBZ和DTX的耐药性。RNA测序确定了RC4-2B中 的表达增加，这通过免疫印迹和免疫荧光分析得到证实。ABCB1特异性抑制剂艾拉司群逆转了RC4-2B细胞对CBZ和DTX的耐药性，证实了ABCB1介导的耐药机制。在使用美国食品药品监督管理局（FDA）批准的细胞毒性药物精选文库进行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）克服了耐药性，在亲本C4-2B和耐药的RC4-2B中表现出相似的细胞毒性。此外，这些化合物对多种对紫杉烷类药物耐药且ABCB1高表达的PC细胞具有细胞毒性，因此可用于克服PCa中对紫杉烷类药物的获得性耐药。最后，用小分子抑制剂（CDK4/6i）抑制CDK4/6激酶增强了CPT或Ara-C在亲本细胞和耐药细胞中的细胞毒性作用。总体而言，我们的研究结果表明，DNA损伤剂CPT和Ara-C单独或与CDK4/6i联合使用可作为CRPC患者的一种新治疗方案，包括那些对紫杉烷类药物耐药的患者。
