Division of Molecular Pharmacology, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
Department of Patient-derived Cancer Model, Tochigi Cancer Center, 4-9-13 Yohnan, Utsunomiya, Tochigi, 320-0834, Japan.
Cell Death Dis. 2023 Feb 27;14(2):169. doi: 10.1038/s41419-023-05690-7.
Translocation-related sarcomas (TRSs) harbor an oncogenic fusion gene generated by chromosome translocation and account for approximately one-third of all sarcomas; however, effective targeted therapies have yet to be established. We previously reported that a pan-phosphatidylinositol 3-kinase (PI3K) inhibitor, ZSTK474, was effective for the treatment of sarcomas in a phase I clinical trial. We also demonstrated the efficacy of ZSTK474 in a preclinical model, particularly in cell lines from synovial sarcoma (SS), Ewing's sarcoma (ES) and alveolar rhabdomyosarcoma (ARMS), all of which harbor chromosomal translocations. ZSTK474 selectively induced apoptosis in all these sarcoma cell lines, although the precise mechanism underlying the induction of apoptosis remained unclear. In the present study, we aimed to determine the antitumor effect of PI3K inhibitors, particularly with regards to the induction of apoptosis, against various TRS subtypes using cell lines and patient-derived cells (PDCs). All of the cell lines derived from SS (six), ES (two) and ARMS (one) underwent apoptosis accompanied by the cleavage of poly-(ADP-ribose) polymerase (PARP) and the loss of mitochondrial membrane potential. We also observed apoptotic progression in PDCs from SS, ES and clear cell sarcoma (CCS). Transcriptional analyses revealed that PI3K inhibitors triggered the induction of PUMA and BIM and the knockdown of these genes by RNA interference efficiently suppressed apoptosis, suggesting their functional involvement in the progression of apoptosis. In contrast, TRS-derived cell lines/PDCs from alveolar soft part sarcoma (ASPS), CIC-DUX4 sarcoma and dermatofibrosarcoma protuberans failed to undergo apoptosis nor induce PUMA and BIM expression, as well as cell lines derived from non-TRSs and carcinomas. Thus, we conclude that PI3K inhibitors induce apoptosis in selective TRSs such as ES and SS via the induction of PUMA and BIM and the subsequent loss of mitochondrial membrane potential. This represents proof of concept for PI3K-targeted therapy, particularly such TRS patients.
易位相关性肉瘤 (TRS) 携带有致癌融合基因，这些基因是由染色体易位产生的，约占所有肉瘤的三分之一；然而，目前尚未建立有效的靶向治疗方法。我们之前报道过，一种全磷脂酰肌醇 3-激酶 (PI3K) 抑制剂 ZSTK474 在一项 I 期临床试验中对肉瘤的治疗有效。我们还在临床前模型中证明了 ZSTK474 的疗效，特别是在滑膜肉瘤 (SS)、尤因肉瘤 (ES) 和腺泡横纹肌肉瘤 (ARMS) 的细胞系中，这些肉瘤都存在染色体易位。ZSTK474 选择性地诱导所有这些肉瘤细胞系凋亡，尽管诱导凋亡的确切机制尚不清楚。在本研究中，我们旨在使用细胞系和患者来源的细胞 (PDC) 确定 PI3K 抑制剂，特别是诱导凋亡，对各种 TRS 亚型的抗肿瘤作用。所有源自 SS (6 个)、ES (2 个) 和 ARMS (1 个) 的细胞系均经历了凋亡，伴随着多聚 (ADP-核糖) 聚合酶 (PARP) 的切割和线粒体膜电位的丧失。我们还观察到 SS、ES 和透明细胞肉瘤 (CCS) 的 PDC 中凋亡的进展。转录分析显示，PI3K 抑制剂触发了 PUMA 和 BIM 的诱导，并且通过 RNA 干扰敲低这些基因有效地抑制了凋亡，这表明它们在凋亡进展中具有功能相关性。相比之下，源自腺泡软组织肉瘤 (ASPS)、CIC-DUX4 肉瘤和隆突性皮肤纤维肉瘤的 TRS 衍生的细胞系/PDC 未能发生凋亡，也未能诱导 PUMA 和 BIM 的表达，以及源自非 TRS 和癌的细胞系也未能诱导 PUMA 和 BIM 的表达。因此，我们得出结论，PI3K 抑制剂通过诱导 PUMA 和 BIM 以及随后线粒体膜电位的丧失，选择性地诱导 ES 和 SS 等 TRS 发生凋亡。这为 PI3K 靶向治疗，特别是此类 TRS 患者提供了概念验证。
