Filik Yüksel, Bauer Karin, Hadzijusufovic Emir, Haider Patrick, Greiner Georg, Witzeneder Nadine, Hoermann Gregor, Hohensinner Philipp J, Gleixner Karoline V, Wojta Johann, Sperr Wolfgang R, Valent Peter
Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna Vienna, Austria.
Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna Vienna, Austria.
Am J Cancer Res. 2021 Dec 15;11(12):6042-6059. eCollection 2021.
Recent data suggest that the disease-associated microenvironment, known as the leukemic stem cell (LSC) niche, is substantially involved in drug resistance of LSC in BCR-ABL1 chronic myeloid leukemia (CML). Attacking the LSC niche in CML may thus be an effective approach to overcome drug resistance. We have recently shown that osteoblasts are a major site of niche-mediated LSC resistance against second- and third-generation tyrosine kinase inhibitors (TKI) in CML. In the present study, we screened for drugs that are capable of suppressing the growth and viability of osteoblasts and/or other niche cells and can thereby overcome TKI resistance of CML LSC. Proliferation was analyzed by determining H-thymidine uptake in niche-related cells, and apoptosis was measured by Annexin-V/DAPI-staining and flow cytometry. We found that the dual PI3 kinase (PI3K) and mTOR inhibitor BEZ235 and the selective pan-PI3K inhibitor copanlisib suppress proliferation of primary osteoblasts (BEZ235 IC: 0.05 μM; copanlisib IC: 0.05 μM), the osteoblast cell line CAL-72 (BEZ235 IC: 0.5 μM; copanlisib IC: 1 μM), primary umbilical vein-derived endothelial cells (BEZ235 IC: 0.5 μM; copanlisib IC: 0.5 μM), and the vascular endothelial cell line HMEC-1 (BEZ235 IC: 1 μM; copanlisib IC: 1 μM), whereas no comparable effects were seen with the mTOR inhibitor rapamycin. Furthermore, we show that BEZ235 and copanlisib cooperate with nilotinib and ponatinib in suppressing proliferation and survival of osteoblasts and endothelial cells. Finally, BEZ235 and copanlisib were found to overcome osteoblast-mediated resistance against nilotinib and ponatinib in K562 cells, KU812 cells and primary CD34/CD38 CML LSC. Together, targeting osteoblastic niche cells through PI3K inhibition may be a new effective approach to overcome niche-induced TKI resistance in CML. Whether this approach can be translated into clinical application and can counteract drug resistance of LSC in patients with CML remains to be determined in clinical trials.
近期数据表明，被称为白血病干细胞（LSC）微环境的疾病相关微环境在BCR-ABL1慢性髓性白血病（CML）中LSC的耐药性方面发挥着重要作用。因此，攻击CML中的LSC微环境可能是克服耐药性的有效方法。我们最近表明，成骨细胞是CML中微环境介导的LSC对第二代和第三代酪氨酸激酶抑制剂（TKI）产生耐药性的主要部位。在本研究中，我们筛选了能够抑制成骨细胞和/或其他微环境细胞生长和活力从而克服CML LSC的TKI耐药性的药物。通过测定与微环境相关细胞中3H-胸腺嘧啶摄取来分析增殖情况，并通过膜联蛋白-V/DNA结合染料染色和流式细胞术测量细胞凋亡。我们发现双PI3激酶（PI3K）和mTOR抑制剂BEZ235以及选择性泛PI3K抑制剂库潘尼西布可抑制原代成骨细胞（BEZ235半数抑制浓度：0.05μM；库潘尼西布半数抑制浓度：0.05μM）、成骨细胞系CAL-72（BEZ235半数抑制浓度：0.5μM；库潘尼西布半数抑制浓度：1μM）、原代脐静脉来源的内皮细胞（BEZ235半数抑制浓度：0.5μM；库潘尼西布半数抑制浓度：0.5μM）以及血管内皮细胞系HMEC-1（BEZ235半数抑制浓度：1μM；库潘尼西布半数抑制浓度：1μM）的增殖，而mTOR抑制剂雷帕霉素未见类似效果。此外，我们表明BEZ235和库潘尼西布与尼洛替尼和波纳替尼协同抑制成骨细胞和内皮细胞的增殖与存活。最后，发现BEZ235和库潘尼西布可克服成骨细胞介导的K562细胞、KU812细胞和原代CD34/CD38 CML LSC对尼洛替尼和波纳替尼的耐药性。总之，通过抑制PI3K靶向成骨细胞微环境细胞可能是克服CML中微环境诱导的TKI耐药性的一种新的有效方法。这种方法能否转化为临床应用并对抗CML患者中LSC的耐药性仍有待在临床试验中确定。
