PO.ET05.01 · 实验与分子治疗
SF3B1抑制通过破坏ATRX剪接并诱导细胞周期阻滞抑制前列腺癌
SF3B1 inhibition suppresses prostate cancer by disrupting ATRX splicing and inducing cell cycle arrest
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
前列腺癌是美国男性最常见的恶性肿瘤，RNA剪接失调已成为前列腺癌进展的关键驱动因素。尽管选择性剪接通路基因在约4%的前列腺癌中发生突变，但核心剪接因子SF3B1的突变占据了不成比例的高比例（27.5%）。然而，SF3B1抑制是否以及如何抑制前列腺癌进展仍不清楚。在此，我们证明SF3B1抑制剂Pladienolide B在前列腺癌细胞系、细胞来源异种移植瘤和患者来源异种移植瘤中发挥强效的抗肿瘤活性。RNA-seq分析揭示了广泛的剪接改变，富集于调控细胞周期阻滞的通路，我们通过流式细胞术和活细胞成像加以验证。经双胸苷同步化后，Pladienolide B处理的DU145细胞表现出显著延长的S期，表明SF3B1抑制主要通过诱导细胞周期阻滞来抑制肿瘤生长。为阐明这种阻滞的分子基础，我们检查了各个剪接变化，并在ATRX中鉴定出一个关键事件：Pladienolide B处理后，ATRX在第25外显子之前保留了一个74-bp的隐性外显子。这种异常剪接破坏了维持基因组稳定性所需的ATRX-MeCP2相互作用——该相互作用通过抑制异染色质中R-loop的积累来发挥作用。有趣的是，我们进一步鉴定出CDK12是SF3B1此前未被认识的上游激酶。CDK12与SF3B1发生物理相互作用，其被THZ531抑制可降低SF3B1在T313位点的磷酸化、诱导细胞周期阻滞并抑制肿瘤生长。鉴于SF3B1抑制的治疗潜力，我们评估了其与当前前列腺癌治疗方案的联合策略。通过THZ531或Pladienolide B抑制SF3B1活性会导致对多西他赛（docetaxel，转移性疾病的一线疗法）产生耐药。值得注意的是，Pladienolide B与PARP抑制剂olaparib联合使用时表现出协同抗肿瘤效应。总之，我们的发现揭示了SF3B1抑制如何通过RNA剪接失调损害前列腺癌进展，并为将SF3B1靶向疗法整合入前列腺癌治疗提供了依据。
查看英文原文 English abstract
Prostate cancer is the most common malignancy in men in the United States, and dysregulated RNA splicing has emerged as a critical driver of prostate cancer progression. Although alternative splicing pathway genes are mutated in approximately 4% of prostate cancers, mutations in the core splicing factor SF3B1 represent a disproportionately high fraction (27.5%). However, whether and how SF3B1 inhibition suppresses prostate cancer progression remains unclear. Here, we demonstrate that the SF3B1 inhibitor Pladienolide B exerts robust antitumor activity in prostate cancer cell lines, cell-derived xenografts, and patient-derived xenografts. RNA-seq analysis revealed widespread splicing alterations enriched in pathways regulating cell-cycle arrest, which we validated using flow cytometry and live-cell imaging. Following double-thymidine synchronization, Pladienolide B-treated DU145 cells exhibited a markedly prolonged S phase, indicating that SF3B1 inhibition suppresses tumor growth primarily by inducing cell-cycle arrest. To elucidate the molecular basis of this arrest, we examined individual splicing changes and identified a key event in ATRX, which retained a 74-bp cryptic exon before exon 25 upon Pladienolide B treatment. This aberrant splicing disrupted the ATRX-MeCP2 interaction required for maintaining genome stability through repression of R-loop accumulation in heterochromatin. Interestingly, we further identified CDK12 as a previously unrecognized upstream kinase of SF3B1. CDK12 physically interacted with SF3B1, and its inhibition by THZ531 reduced SF3B1 phosphorylation at T313, induced cell-cycle arrest, and suppressed tumor growth. Given the therapeutic potential of SF3B1 inhibition, we evaluated combinatorial strategies with current prostate cancer treatments. Inhibition of SF3B1 activity by THZ531 or Pladienolide B conferred resistance to docetaxel, a first-line therapy for metastatic disease. Notably, Pladienolide B exhibited synergistic antitumor effects when combined with the PARP inhibitor olaparib. Collectively, our findings reveal how SF3B1 inhibition impairs prostate cancer progression through RNA splicing dysregulation, and they provide a rationale for integrating SF3B1-targeted therapies into prostate cancer treatment.
利益披露 Disclosure
L. Li, None..
W. Ding, None..
Z. Nie, None..
C. Jiang, None..
R. Zhao, None..
S. Xia, None..
B. Zhang, None.