香茶菜中Isoforrestin A联合GSH合成抑制剂逆转伊马替尼耐药的作用及机制

Imatinib resistance is an important problem to be solved in the treatment of chronic myeloid leukemia. Rabdosia Species plants are traditional Chinese medicines with heat-clearing and toxin-resolving functions used for a long history. Isoforrestin A, an active compound screened from Isodon forrestii var. forrestii, showed anti-tumor effect with little side effects on xenograft models. These results have been published on the journal Cancer Research. Previous studies focused on solid tumors, so the effect of Isoforrestin A on leukemia was unclear, and its combination regimen was still unknown. In the following studies, the applicant found that Isoforrestin A significantly inhibited both imatinib-sensitive and imatinib-resistant chronic myeloid leukemia cells. GSH synthesis inhibitor BSO synergizes with Isoforrestin A to induce apoptosis in imatinib-resistant K562R cells. These results suggested that BSO combined with Isoforrestin A could overcome imatinib resistance. Therefore, we will further explore the functions and underlying mechanisms of Isoforrestin A combined with GSH synthesis inhibitor in overcoming imatinib resistance. This project is expected to explore new ideas for reversing imatinib resistance and to provide a theoretical support for the clinical transformation of Isoforrestin A.

伊马替尼耐药是慢性粒细胞白血病治疗中亟待解决的重要问题。香茶菜是我国药用历史悠久的清热解毒类中药。Isoforrestin A（IsoA）是申请人从香茶菜中筛选得到的一个具有抗肿瘤效应的活性单体，毒副作用小，该成果已在Cancer Research杂志发表。申请人前期研究聚焦在实体瘤，而IsoA在血液瘤的效果尚不明确，其联合用药方案也是未知领域。申请人在后续研究中发现，IsoA对伊马替尼敏感和耐药的慢性粒细胞白血病细胞均有显著抑制作用，GSH合成抑制剂BSO对IsoA具有增敏作用，提示二者联合用药具有协同逆转伊马替尼耐药的作用。因此，本项目拟在前期结果的基础上，深入探讨IsoA与GSH合成抑制剂联用在逆转伊马替尼耐药中的作用和机制。本项目预期研究成果将为逆转伊马替尼耐药提供新思路，也为IsoA的临床转化提供理论基础。

慢性粒细胞白血病（Chronic myeloid leukemia, CML）是一种恶性的骨髓及外骨髓异常增殖的造血干细胞性疾病。尽管分子靶向药伊马替尼（Imatinib, IM）极大地改善了CML的治疗效果，但耐药问题却如影随形。硫氧还蛋白(Thioredoxin 1, Trx1)是细胞中重要的抗氧化蛋白，与肿瘤密切相关，但其在CML尤其是IM耐药的作用尚不明确。本研究发现，Trx1在CML病人的表达显著高于正常对照，其在IM耐药株的表达显著高于敏感株。干扰Trx1表达可显著抑制CML细胞（包括敏感株和耐药株）生长、增殖和克隆形成，还能削弱CML细胞在小鼠体内的成瘤能力。其次，Trx1抑制剂Isoforrestin A对IM敏感和耐药的CML白血病细胞均有显著抑制作用，GSH合成抑制剂BSO对IsoA具有协同增敏作用。从机制上来说，IsoA和BSO联合使用可诱导CML内活性氧增加、还原性GSH降低，引起细胞内脂质过氧化，进而导致细胞铁死亡。通过筛选发现，IsoA和BSO联合使用主要通过诱导GSTA1、SAT1、CP、CDO1、KEAP1、USP7、ALDH1A等基因表达，抑制STEAP3、GPX4等，导致了CML细胞的铁死亡。最后，通过构建CML小鼠模型中，IsoA与BSO联合使用后，结果发现两者可有效抑制肿瘤生长，具有协同效应。本研究结果为CML的治疗及IM耐药提供了新的潜在靶点，并据此提供了新的组合用药策略，同时也为传统中药成分的转化研究提供了理论参考。