Coignard, S. | bioRxiv Science

bioRxiv2023

BCR-ABL promotes hematopoietic stem and progenitor cell formation in embryonic stem cells

Generating Hematopoietic Stem Cells (HSCs) from Pluripotent Stem Cells (PSCs) has been a long-lasting quest in the field of hematopoiesis. Previous studies suggested that enforced expression of BCR-ABL, the unique oncogenic driver of Chronic Myelogeneous Leukemia (CML), in Embryonic Stem Cells (ESCs)-derived hematopoietic cells is sufficient to confer long-term in vivo repopulating potential. To precisely uncover the molecular events regulated by the Tyrosine-kinase activity of BCR-ABL1 (p210) during the course of hematopoietic differentiation, we engineered a Tet-ON inducible system to modulate its expression in murine ESC. We showed in unique site-directed knock-in ESC model, that BCR-ABL expression tightly regulated by doxycycline (dox) controls the formation and the maintenance of immature hematopoietic progenitors. Interestingly, these progenitors can be expanded in vitro for several passages in the presence of dox. Our analysis of cell surface markers and transcriptome compared to wild-type fetal and adult HSCs unraveled a similar molecular signature. LTC-IC assay confirmed their self-renewal capacities albeit with a differentiation bias towards erythroid and myeloid cells. Collectively, our novel Tet-ON system represents a unique in vitro model to shed lights on ESC-derived hematopoiesis, CML initiation and maintenance. KEY POINTSO_LIWe report a unique BCR-ABL-induced-embryonic stem cell -derived hematopoiesis model in murine embryonic stem cells C_LIO_LIThis BCR-ABL-induced self-renewal and differentiation model can be of major interest to uncover molecular events required for ESC-derived hematopoiesis C_LI

cancer biology↗

bioRxiv2022

miR-495-3p Sensitizes BCR::ABL1 Expressing Leukemic cells to Tyrosine Kinase Inhibitors by Targeting Multidrug Resistance 1 Gene including in T315I Mutated cells

Chronic myeloid leukemia (CML) is a clonal hematopoietic malignancy driven by the BCR::ABL1 fusion oncoprotein. The development of tyrosine kinase inhibitors (TKIs) has deeply increased long-term survival of CML patients. Nonetheless, one patient out of four will switch TKI off owing either to drug intolerance or resistance partly due to amplification or mutations of BCR::ABL1 oncogene and alteration of ATP-binding cassette (ABC) transporters. Increasing evidence suggests an involvement of the microRNA miR-495-3p in cancer-associated chemo-resistance through multidrug resistance 1 (MDR1) gene which encodes an ATP-dependent efflux pump. Our study aimed at investigating the potential role of miR-495-3p in CML TKI chemo-sensitivity and determining the underlying molecular circuitry involved. We first observed that miR-495-3p expression was lower in BCR::ABL1 expressing cellular models in vitro. Notably, loss-of-function experiments showed increased proliferation associated with a decreased number of non-dividing cells (G0/G1) and resistance to Imatinib. Conversely, our data showed that miR-495-3p overexpression hindered leukemic cell growth and TKI resistance even in Imatinib-resistant T315I-mutant cells as well as drug efflux activity through MDR1 regulation. To further investigate the role of miR-495-3p in CML patients, we found that predicted miR-495-3p targets were upregulated in patients in blast crisis involved in protein phosphorylation and associated with the worst prognosis. Taken together, our results demonstrate that down-regulation of miR-495-3p expression is important in the malignant phenotype of CML and TKI resistance mechanisms, which could be a useful biomarker and a potential therapeutic target to eradicate CML. MeSH termsO_LIATP Binding Cassette Transporter, Subfamily B C_LIO_LIATP Binding Cassette Transporter, Subfamily B, Member 1 / drug effects C_LIO_LIATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism* C_LIO_LIBlast Crisis / pathology C_LIO_LICell Line, Tumor C_LIO_LICell Proliferation / drug effects* C_LIO_LICell Survival / drug effects C_LIO_LIDrug Resistance C_LIO_LIGenes, MDR C_LIO_LIImatinib Mesylate C_LIO_LILeukemia, Myelogenous, Chronic, BCR-ABL Positive C_LIO_LIMicroRNAs / genetics C_LIO_LIMicroRNAs / physiology* C_LI HIGHLIGHTSO_LImiR-495-3p inhibits leukemic cell growth and is downregulated in BCR::ABL1 expressing cell lines C_LIO_LImiR-495-3p modulates response to TKI treatment including in UT7 cells expressing T315I C_LIO_LIOverexpression of miR-495-3p leads to a decrease of MDR1 and drug efflux activity C_LIO_LIBioinformatics analyses reveal that MiR-495-3p target genes are upregulated in blast crisis C_LI

cancer biology↗