Role of CYP3A4 in Prostate Cancer

描述（由申请人提供）：去势抵抗性前列腺癌（CRPC）是无法治愈的，因为目前的抗CRPC治疗只能延长几个月的生命。细胞色素P450 3A4 （3A4）是一种代谢和灭活多种外源药物的酶，包括抗crpc药物阿比特龙和多西他赛。虽然这种代谢通常发生在肝脏，但初步数据显示，与正常前列腺细胞相比，前列腺癌（PCa）细胞中3A4 （mRNA和蛋白）的表达和活性升高。此外，膳食补充剂4- methylumbellliferone （MU）下调PCa细胞中3A4的表达；因此MU下调3A4活性，增强抗crpc药物的细胞毒性作用。有趣的是，由DNA多态性产生的3a4 -变体（3A41B）与PCa转移相关，并且具有高启动子活性。这个探索性项目旨在解决PCa生物学中一个未被充分研究的领域：3A4在PCa细胞中的表达升高是其对抗crpc药物敏感性降低的机制吗？此外，通过一种无毒的膳食补充剂，下调3A4在PCa细胞中的表达，是否会增强PCa细胞对抗CRPC药物的敏感性？3A4在PCa细胞中的作用将通过确定3A4水平的调节（过表达和沉默）和MU治疗是否改变PCa细胞对抗crpc药物的敏感性来研究。此外，在PCa细胞中表达的3A4是否会使抗crpc药物失活，MU是否会阻止这种失活？研究还将探讨MU下调3A4水平的机制；具体来说，MU是否增加了3A4 mRNA的降解或转录沉默3A4野生型和变体3A41B启动子。在异种移植模型中，我们将测试抗crpc药物单独使用或与MU联合使用对去势抵抗性前列腺肿瘤生长和进展的抑制效果。用于异种移植的PCa细胞将是那些3A4表达上调或下调的细胞。影响：本探索性项目旨在揭示PCa细胞中表达的3A4在调节PCa细胞对抗crpc药物反应中的作用。此外，与特异性靶向3A4表达的无毒膳食补充剂联合使用可增强PCa细胞对抗crpc药物的敏感性。如果成功，该项目具有临床转化的潜力，根据肿瘤中的3A4水平，可以添加3A4抑制剂来改善抗crpc治疗的反应。

DESCRIPTION (provided by applicant): Castration resistant prostate cancer (CRPC) is incurable as the current anti-CRPC treatments do not extend life beyond a few months. Cytochrome P450 3A4 (3A4) is an enzyme that metabolizes and inactivates a number of xenobiotics, including anti-CRPC drugs Abiraterone and Docetaxel. Although, such metabolism usually occurs in the liver, preliminary data show elevated expression of 3A4 (mRNA and protein) and activity in prostate cancer (PCa) cells, when compared to normal prostate cells. Further, a dietary supplement, 4-methylumbelliferone (MU) downregulates 3A4 expression in PCa cells; consequently MU downregulates 3A4 activity and enhances cytotoxic effects of anti-CRPC drugs. Interestingly, a 3A4-variant (3A41B) generated by DNA polymorphism correlates with PCa metastasis and has high promoter activity. This exploratory project is designed to address an understudied area in PCa biology: is elevated expression of 3A4 in PCa cells a mechanism for their reduced sensitivity to anti-CRPC agents? Further, does downregulation of 3A4 expression in PCa cells, by a non-toxic dietary supplement, enhance the sensitivity of PCa cells to anti- CRPC agents? The role of 3A4 in PCa cells will be examined by determining whether modulation of 3A4 levels (over expression and silencing) and MU treatment alters the sensitivity of PCa cells to anti-CRPC agents. Furthermore, does 3A4 expressed in PCa cells inactivate anti-CRPC drugs and whether MU prevents this inactivation? Studies will also investigate the mechanism by which MU downregulates 3A4 levels; specifically, whether MU increases the degradation of 3A4 mRNA or transcriptionally silences both 3A4 wild type and variant 3A41B promoters. Efficacy of anti-CRPC agents, either alone or in combination with MU will be tested to inhibit the growth and progression of castration-resistant prostate tumors in xenograft models. PCa cells used in the xenograft will be those in which 3A4 expression is either up- or down-regulated. Impact: This exploratory project should reveal the role of 3A4 expressed in PCa cells in modulating the response of PCa cells to anti-CRPC agents. Furthermore, does combination with a non-toxic dietary supplement that specifically targets 3A4 expression enhances the sensitivity of PCa cells to anti-CRPC agents. If successful, the project has potential for clinical translation, in which based on the 3A4 levels in tumors a 3A4 inhibitor could be added to improve response to anti-CRPC treatments.