Key Laboratory of Study and Discovery of Small Targeted Molecules of Hunan Province, Department of Pharmacy, School of Medicine, Hunan Normal University, Changsha, 410013, China; Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Yantai University, Yantai, 264005, China.
Department of Oncology, The Affiliated Zhuzhou Hospital of Xiangya School of Medicine, Central South University, Zhuzhou, 412007, China; Obstetrics and Gynecology Department, Xiangya Hospital, Central South University, Changsha, 410008, China; Departments of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, China.
Int J Biol Sci. 2022 Jan 24;18(4):1555-1568. doi: 10.7150/ijbs.62947. eCollection 2022.
Poly (ADP-ribose) polymerase inhibitors (PARPi) have showed clinical benefit as maintenance therapy in advanced ovarian cancer by impairing the homologous recombination (HR) pathway. Pyruvate kinase M2 (PKM2), the significant cancer metabolic biomarker, integrates with DNA damage to directly promote HR. We aimed to investigate the role and molecular mechanism of PKM2 downregulation on sensitization of ovarian cancer cells to PARPi. Inhibitory effects in vitro were assessed by cell viability, clone formation, transwell assay, and flow cytometry. Downregulation of PKM2 by siRNA or small molecular inhibitor shikonin (Sk) enhanced anti-tumour activity of olaparib (Ola) in ovarian cancer cells. Silencing PKM2 or Sk synergized with Ola and reduced cell growth, colony formation and migration, and induced apoptosis. Western blot and immunofluorescence demonstrated that inhibition of PKM2 amplified Ola-induced γH2AX and phospho-ATM (p-ATM) activation and interfered with BRCA1 accumulation in the nucleus. A xenograft animal model demonstrated in vivo antitumor combination effect of Sk and Ola. Furthermore, Western blot and immunofluorenscent analyses of tissue samples revealed that treatment of Sk increased DNA damage, reduced expression of BRCA1 and PKM2. Therefore, this study identified that PKM2 downregulation is a novel therapeutic strategy to enhance Ola effectiveness in treating ovarian cancer.
聚（ADP-核糖）聚合酶抑制剂（PARPi）通过损害同源重组（HR）途径，在晚期卵巢癌的维持治疗中显示出临床益处。丙酮酸激酶 M2（PKM2），一种重要的癌症代谢生物标志物，与 DNA 损伤整合，直接促进 HR。我们旨在研究下调 PKM2 对卵巢癌细胞对 PARPi 敏感性的作用和分子机制。通过细胞活力、克隆形成、transwell 测定和流式细胞术评估体外抑制作用。通过 siRNA 或小分子抑制剂紫草素（Sk）下调 PKM2 增强了奥拉帕利（Ola）在卵巢癌细胞中的抗肿瘤活性。沉默 PKM2 或 Sk 与 Ola 协同作用，降低细胞生长、集落形成和迁移，并诱导细胞凋亡。Western blot 和免疫荧光显示，抑制 PKM2 增强了 Ola 诱导的 γH2AX 和磷酸化 ATM（p-ATM）激活，并干扰了 BRCA1 在核内的积累。异种移植动物模型证明了 Sk 和 Ola 的体内抗肿瘤联合作用。此外，组织样本的 Western blot 和免疫荧光分析显示，Sk 处理增加了 DNA 损伤，降低了 BRCA1 和 PKM2 的表达。因此，本研究确定下调 PKM2 是增强 Ola 治疗卵巢癌有效性的一种新的治疗策略。
