BRD4-targeted proteolysis targeting chimera (PROTAC) have exhibited promising in vitro and in vivo anticancer activity in a number of cancer models. However, the clinical development of current reported BRD4-PROTACs have stagnated, largely due to the safety risks caused by their poor degradation selectivity. In this study, we designed and synthesized a series of PROTACs based on our recently reported dual BET/PLK1 inhibitor WNY0824, which led to the discovery of an isoform-selective and potent BRD4-PROTAC 12a (WWL0245). WWL0245 exhibited excellent selective cytotoxicity in the BETi sensitive cancer cell lines, including AR-positive prostate cancer cell lines. It could also efficiently induce ubiquitin-proteasomal degradation of BRD4 in AR-positive prostate cancer cell lines, with sub-nanomolar half-maximal degrading concentration (DC₅₀) and maximum degradation (D_max) > 99%. Moreover, WWL0245 induced cell cycle arrest at the G0/G1 phase and apoptosis in AR-positive prostate cancer by downregulation of the protein levels of AR, PSA and c-Myc as well as transcriptionally suppressed AR-regulated genes. WWL0245 was thus expected to be developed as a promising drug candidate for AR-positive prostate cancer and a valuable tool compound to study the biological function of BRD4.

BRD4 靶向蛋白水解靶向嵌合体 (PROTAC) 在多种癌症模型中表现出良好的体外和体内抗癌活性。然而，目前报道的BRD4-PROTACs的临床开发已经停滞，很大程度上是由于其降解选择性差带来的安全风险。在本研究中，我们基于最近报道的双重 BET/PLK1 抑制剂WNY0824设计并合成了一系列 PROTAC，从而发现了异构体选择性且有效的 BRD4-PROTAC 12a ( WWL0245) 。 WWL0245在 BETi 敏感癌细胞系（包括 AR 阳性前列腺癌细胞系）中表现出优异的选择性细胞毒性。它还可以在 AR 阳性前列腺癌细胞系中有效诱导 BRD4 泛素蛋白酶体降解，半最大降解浓度 (DC ₅₀ ) 为亚纳摩尔级，最大降解浓度 (D _max ) > 99%。此外， WWL0245通过下调 AR、PSA 和 c-Myc 的蛋白水平以及转录抑制 AR 调节基因，诱导 AR 阳性前列腺癌的细胞周期停滞在 G0/G1 期和细胞凋亡。因此， WWL0245有望被开发为治疗AR阳性前列腺癌的有前途的候选药物和研究BRD4生物学功能的有价值的工具化合物。