Yu Xiaobing, Munoz-Sagredo Leonel, Streule Karolin, Muschong Patricia, Bayer Elisabeth, Walter Romina J, Gutjahr Julia C, Greil Richard, Concha Miguel L, Müller-Tidow Carsten, Hartmann Tanja N, Orian-Rousseau Véronique
Karlsruhe Institute of Technology, Institute of Biological and Chemical Systems-Functional Molecular Systems, Karlsruhe, Germany.
Department of Medicine, Hematology, Oncology and Rheumatology, Heidelberg University, Heidelberg, Germany.
Blood. 2021 Sep 23;138(12):1067-1080. doi: 10.1182/blood.2020006343.
Acute myeloid leukemia (AML) has a poor prognosis under the current standard of care. In recent years, venetoclax, a BCL-2 inhibitor, was approved to treat patients who are ineligible for intensive induction chemotherapy. However, complete remission rates with venetoclax-based therapies are hampered by minimal residual disease (MRD) in a proportion of patients, leading to relapse. MRD is a result of leukemic stem cells being retained in bone marrow protective environments; activation of the CXCL12-CXCR4 pathway was shown to be relevant to this process. An important role is also played by cell adhesion molecules such as CD44, which has been shown to be crucial for the development of AML. Here we show that CD44 is involved in CXCL12 promotion of resistance to venetoclax-induced apoptosis in human AML cell lines and AML patient samples, which could be abrogated by CD44 knock down, knockout, or blocking with an anti-CD44 antibody. Split-Venus bimolecular fluorescence complementation showed that CD44 and CXCR4 physically associate at the cell membrane upon CXCL12 induction. In the venetoclax-resistant OCI-AML3 cell line, CXCL12 promoted an increase in the proportion of cells expressing high levels of embryonic stem cell core transcription factors (ESC-TFs: Sox2, Oct4, Nanog) abrogated by CD44 knockdown. This ESC-TF-expressing subpopulation which could be selected by venetoclax treatment, exhibited a basally enhanced resistance to apoptosis and expressed higher levels of CD44. Finally, we developed a novel AML xenograft model in zebrafish, which showed that CD44 knockout sensitizes OCI-AML3 cells to venetoclax treatment in vivo. Our study shows that CD44 is a potential molecular target for sensitizing AML cells to venetoclax-based therapies.
在当前的治疗标准下，急性髓系白血病（AML）的预后较差。近年来，BCL-2抑制剂维奈托克被批准用于治疗不符合强化诱导化疗条件的患者。然而，一部分患者的微小残留病（MRD）阻碍了基于维奈托克的治疗方案的完全缓解率，导致疾病复发。MRD是白血病干细胞保留在骨髓保护环境中的结果；CXCL12-CXCR4通路的激活与这一过程相关。细胞黏附分子如CD44也发挥着重要作用，已证明其对AML的发展至关重要。在此，我们表明CD44参与了CXCL12促进人AML细胞系和AML患者样本对维奈托克诱导的凋亡的抗性，这种抗性可通过敲低、敲除CD44或用抗CD44抗体阻断来消除。分裂型维纳斯双分子荧光互补显示，在CXCL12诱导下，CD44与CXCR4在细胞膜上发生物理缔合。在对维奈托克耐药的OCI-AML3细胞系中，CXCL12促进了表达高水平胚胎干细胞核心转录因子（ESC-TFs：Sox2、Oct4、Nanog）的细胞比例增加，敲低CD44可消除这种增加。这种可通过维奈托克治疗选择出来的表达ESC-TF的亚群表现出对凋亡的基础抗性增强，且CD44表达水平更高。最后，我们在斑马鱼中建立了一种新型AML异种移植模型，该模型显示敲除CD44可使OCI-AML3细胞在体内对维奈托克治疗敏感。我们的研究表明，CD44是使AML细胞对基于维奈托克的治疗敏感的潜在分子靶点。
