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S. Geyh et al.
the first time that activated TGFβ signaling contributes significantly to ineffective hematopoiesis in MDS and AML via functional inhibition of MSC.
Envisaging targeted stromal therapies, it is of particular interest that we could pharmacologically revert the sup- pressive effects of TGFβ1 on healthy MSC in vitro using SD-208. This small molecule pyridopyrimidine inhibitor of TGFβ receptor I abrogates the signaling downstream of TGFβ receptor I, independently of the specific ligand. SD- 208 has been shown to stimulate hematopoiesis in a mouse model of bone marrow failure as well as when MDS HSPC were cultured in vitro.23 In agreement with these findings, SD-208 was also able to restore the osteogenic differentiation capacity and, with a clear trend, the hematopoietic support capacity of MDS- and AML- derived MSC in our analysis. Targeting TGFβ signaling to improve hematopoiesis is the aim of two ligand-trapping approaches with luspatercept and sotatercept, currently under clinical investigation in MDS.40,41 Of particular inter- est, the effects of the latter are not mediated via CD34+ HSPC but rather via the stromal compartment,41 thus fur- ther supporting the role of TGFβ-mediated stromal inhibi- tion in MDS and AML. At this point it remains unclear whether TGFβ1-mediated functional inhibition of MSC in MDS and AML is a cell-intrinsic mechanism or is extrinsi- cally mediated by other TGFβ1-producing cells within the bone marrow microenvironment. While Chen et al. recently detected overexpression of TGFβ1 in FACS-sort- ed unexpanded MSC of patients exclusively with low-risk MDS, we did not find overexpression of TGFβ1 in culture- expanded MSC derived from patients with early or advanced MDS or AML (data not shown). On the other hand, we did find mRNA overexpression of TGFβ1 in CD34+ HSPC of patients with MDS or AML by perform- ing quantitative PCR as well as by analyzing data from
173 AML samples in comparison to 967 samples from 28 different healthy tissues included in The Cancer Genome Atlas database (Online Supplementary Figures S13 and S14). This suggests that TGFβ1 released from CD34+ HSPC may contribute, at least in part, to the inhibition of MSC in MDS and AML. In further support of an extrinsic mecha- nism, it was recently shown that myeloid-derived sup- pressor cells also overproduce TGFβ1 and thereby sup- press hematopoiesis in MDS.42 Overall, these data imply that different cells may be involved as sources of TGFβ1 and TGFβ1-related inhibition of hematopoiesis in MDS and AML. Indeed, since there may even be variations between early and advanced MDS as well as between MDS and AML this issue needs to be addressed in future studies.
In conclusion, our RNA sequencing analysis revealed a specific molecular signature of MDS- and AML-derived MSC which reflected and explained these cells’ structural and functional deficits. By subsequent functional testing we confirmed that TGFβ1 is a relevant trigger for the molecular alterations and functional inhibition of MSC in MDS and AML. Our results also further support targeting of this signal pathway as a promising treatment approach.
Acknowledgments
This work was supported by a grant from the Deutsche Forschungsgemeinschaft (SCHR 1470/1-1), the Research Committee of the Medical Faculty, Heinrich-Heine-University, Duesseldorf, Germany and the Leukämie Lymphom Liga e. V., Duesseldorf, Germany to TS.
We would like to thank Dennis Sohn from the Laboratory of Molecular Radio-oncology, Clinic and Polyclinic for Radiation Therapy and Radio-oncology for technical assistance regarding LTC-IC assays.
References
1. Shastri A, Will B, Steidl U, Verma A. Stem and progenitor cell alterations in myelodys- plastic syndromes. Blood. 2017;129(12): 1586-1594.
2. Thomas D, Majeti R. Biology and relevance of human acute myeloid leukemia stem cells. Blood. 2017;129(12):1577-1585.
3. Medyouf H. The microenvironment in human myeloid malignancies: emerging concepts and therapeutic implications. Blood. 2017;129(12):1617-1626.
4. Schroeder T, Geyh S, Germing U, Haas R. Mesenchymal stromal cells in myeloid malignancies. Blood Res. 2016;51(4):225- 232.
5. Kode A, Manavalan JS, Mosialou I, et al. Leukaemogenesis induced by an activating beta-catenin mutation in osteoblasts. Nature. 2014;506(7487):240-244.
6. RaaijmakersMH,MukherjeeS,GuoS,etal. Bone progenitor dysfunction induces myelodysplasia and secondary leukaemia. Nature. 2010;464(7290):852-857.
7. Frisch BJ, Ashton JM, Xing L, et al. Functional inhibition of osteoblastic cells in an in vivo mouse model of myeloid leukemia. Blood. 2012;119(2):540-550.
8. Hanoun M, Zhang D, Mizoguchi T, et al. Acute myelogenous leukemia-induced sym- pathetic neuropathy promotes malignancy in an altered hematopoietic stem cell niche. Cell Stem Cell. 2014;15(3):365-375.
9. Schepers K, Pietras EM, Reynaud D, et al. Myeloproliferative neoplasia remodels the endosteal bone marrow niche into a self- reinforcing leukemic niche. Cell Stem Cell. 2013;13(3):285-299.
10. Chen S, Zambetti NA, Bindels EM, et al. Massive parallel RNA sequencing of highly purified mesenchymal elements in low-risk MDS reveals tissue-context-dependent acti- vation of inflammatory programs. Leukemia. 2016;30(9):1938-1942.
11. Ferrer RA, Wobus M, List C, et al. Mesenchymal stromal cells from patients with myelodyplastic syndrome display dis- tinct functional alterations that are modulat- ed by lenalidomide. Haematologica. 2013;98(11):1677-1685.
12. Geyh S, Oz S, Cadeddu RP, et al. Insufficient stromal support in MDS results from molec- ular and functional deficits of mesenchymal stromal cells. Leukemia. 2013;27(9):1841- 1851.
13. Geyh S, Rodriguez-Paredes M, Jager P, et al. Functional inhibition of mesenchymal stro- mal cells in acute myeloid leukemia.
Leukemia. 2016;30(3):683-691.
14. Medyouf H, Mossner M, Jann JC, et al.
Myelodysplastic cells in patients reprogram mesenchymal stromal cells to establish a transplantable stem cell niche disease unit. Cell Stem Cell. 2014;14(6):824-837.
15. von der Heide EK, Neumann M, Vosberg S, et al. Molecular alterations in bone marrow mesenchymal stromal cells derived from acute myeloid leukemia patients. Leukemia. 2017;31(5):1069-1078.
16. Schroeder T, Czibere A, Zohren F, et al. Meningioma 1 gene is differentially expressed in CD34 positive cells from bone marrow of patients with myelodysplastic syndromes with the highest expression in refractory anemia with excess of blasts and secondary acute myeloid leukemia. Leuk Lymphoma. 2009;50(6):1043-1046.
17. Kim D, Pertea G, Trapnell C, et al. TopHat2: accurate alignment of transcriptomes in the presence of insertions, deletions and gene fusions. Genome Biol. 2013;14(4):R36.
18. Love MI, Huber W, Anders S. Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2. Genome Biol. 2014;15(12):550.
19. Trapnell C, Hendrickson DG, Sauvageau M, et al. Differential analysis of gene regulation at transcript resolution with RNA-seq. Nat
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