丹参酮调控HIF-1α/SDF-1/CXCR4轴干预骨髓微环境CML微小残留病灶的机制研究

Chronic Myeloid leukemia (CML) is a hematopoietic cell disease that is characterized by the existence of the Bcr-Abl fusion oncogene resulting from the reciprocal translocation. Imatinib mesylate (IM), a specific tyrosine kinase inhibitor of Bcr-Abl, achieves durable responses in most patients with newly diagnosed CML in the chronic phase. However, despite the success of IM in treating CML, the majority of patients continue to present with minimal residual disease (MRD) contained within the bone marrow (BM) microenvironment. The persistence minimal residual disease may be responsible for CML resistance and results in hematologic relapse. Thus, therapeutic strategies targeting MRD would increase the sensitivity of IM in CML cells.. .The bone marrow microenvironment is comprised of multiple sub-domains which vary in cellular composition and gradients of soluble factors and matrix composition. Experimental evidence indicates that bone marrow microenvironment confer a multi-drug resistance phenotype for minimal residual leukemia. In the context of CML, the BM is highly hypoxic, and that progression of the disease is associated with expansion of hypoxic niches and stabilization of the oncogenic hypoxia-inducible factor (HIF)-1α. HIF-1α also directly up-regulates the expression of stromal derived factor-1 (SDF-1) and its receptor CXCR4. While the interaction between CXCL12 and CXCR4 activates the intrinsic pathway of homing and engraftment in CML cells. Since the importance of BM microenvironment in drug resistance and minimal residual disease development, disruption of the crosstalk of CML cells with BM microenvironment would lead to their re-sensitization to therapeutic agents, and contribute the elimination of the MRD...Tanshinones, diterpene compounds from the root of Salvia miltiorrhiza Bunge, have exhibited significant activities in improving hypoxia-induced injury and HIF-1α inhibition. Our previous results demonstrated that Tanshinones could inhibit the expression of HIF-1α induced by hypoxia in CML cells, indicating potential applications in overcoming bone marrow microenvironment mediated imatinib resistance. The aim of this study was to determine the effect of Tanshinones on the minimal residual disease in BM microenvironment, and elucidate its specific mechanisms. We would measure the MRD levels and imatinib sensitivity after Tanshinones treatment, investigate the activities of HIF-1α/SDF-1/CXCR4 axis and O2 partial pressure in bone marrow microenvironment, evaluate the ability of CML adhesion and trafficking in vivo and in vitro. The combination of Tanshinones and imatinib might be beneficial to target MRD, providing a potential therapeutic strategy to override drug resistance in CML and suppress or eradicate residual disease. Furthermore, elucidating the role and mechanism of HIF-1α/SDF-1/CXCR4 axis in the response to chemo-therapeutic treatment may contribute to the development of novel agents targeting hypoxic bone marrow microenvironment in CML.

慢性粒细胞白血病(CML)患者获得完全缓解后，少量的CML细胞聚集于骨髓微环境中形成微小残留病灶(MRD)，是导致耐药和复发的根源。低氧骨髓微环境和高表达HIF-1α为MRD提供了天然庇护所，其下游效应分子SDF-1和CXCR4在MRD的形成和发展中发挥了重要调控功能，靶向HIF-1α/SDF-1/CXCR4轴的药物开发有助于体内MRD的清除，改善患者预后。结合前期研究结果，本课题以丹参酮为研究对象，系统研究其对CML骨髓微环境和MRD的作用，评价丹参酮联合伊马替尼的体内外药效，检测丹参酮对微环境中氧分压和HIF-1α表达的影响，明确丹参酮对CML粘附和趋化的调控功能，“多途径、多靶点”阐明丹参酮调控HIF-1α/SDF-1/CXCR4轴的分子机制。本研究将明确丹参酮对MRD的干预作用，为其后续的开发奠定基础，为改善缓解期患者的复发提供新的策略，有助于患者无病生存期的延长。

慢性粒细胞白血病(CML)患者获得完全缓解后，少量的CML细胞聚集于骨髓微环境中形成微.小残留病灶(MRD)，是导致耐药和复发的根源。低氧骨髓微环境为MRD提供了天然庇护所。本课题采用骨髓来源的大鼠MSC细胞、人HS-5细胞、人MSC细胞，研究骨髓基质细胞对CML耐药的影响，并对其机制进行了研究。结果表明，CML细胞与骨髓基质细胞共培养，可降低CML对伊马替尼的敏感性。深入研究发现，低氧条件下，骨髓基质细胞与CML细胞共培养的条件培养基具有诱导CML细胞耐药的功能。对该条件培养基进行分析，发现其中SDF-1、IL-6、IL-8等炎症因子高表达。通过外源性的加入IL-6R的中和抗体，发现阻断IL-6相关通路可逆转条件培养基介导的CML耐药。进一步研究丹参酮对CML骨髓微环境和CML耐药的作用。通过动物实验和细胞水平实验，证实丹参酮具有逆转骨髓基质细胞介导CML耐药的功能。丹参酮可以抑制骨髓基质细胞分泌NF-κB通路抑制IL-6的分泌，进而增加CML细胞对伊马替尼的敏感性。本研究明确了丹参酮对骨髓微环境的干预作用，为其后续的开发奠定基础，为改善缓解期患者的复发提供新的策略，有助于患者无病生存期的延长。