RESUMO
Despite decades of research, standard therapies remain ineffective for most leukemias, pushing toward an essential unmet need for targeted drug screens. Moreover, preclinical drug testing is an important consideration for success of clinical trials without affecting non-transformed stem cells. Using the transgenic chronic myeloid leukemia (CML) mouse model, we determine that leukemic stem cells (LSCs) are transcriptionally heterogenous with a preexistent drug-insensitive signature. To test targeting of potentially important pathways, we establish ex vivo expanded LSCs that have long-term engraftment and give rise to multilineage hematopoiesis. Expanded LSCs share transcriptomic signatures with primary LSCs including enrichment in Wnt, JAK-STAT, MAPK, mTOR and transforming growth factor ß signaling pathways. Drug testing on expanded LSCs show that transforming growth factor ß and Wnt inhibitors had significant effects on the viability of LSCs, but not leukemia-exposed healthy HSCs. This platform allows testing of multiple drugs at the same time to identify vulnerabilities of LSCs.
Assuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva , Transcriptoma , Camundongos , Animais , Células-Tronco Neoplásicas/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Fator de Crescimento Transformador beta/metabolismoRESUMO
Hematopoietic stem cell transplantation (HSCT) is a frequent therapeutic approach to restore hematopoiesis in patients with hematologic diseases. Patients receive a hematopoietic stem cell (HSC)-enriched donor cell infusion also containing immune cells, which may have a beneficial effect by eliminating residual neoplastic cells. However, the effect that donor innate immune cells may have on the donor HSCs has not been deeply explored. Here, we evaluate the influence of donor natural killer (NK) cells on HSC fate, concluded that NK cells negatively affect HSC frequency and function, and identified interferon-gamma (IFNγ) as a potential mediator. Interestingly, improved HSC fitness was achieved by NK cell depletion from murine and human donor infusions or by blocking IFNγ activity. Thus, our data suggest that suppression of inflammatory signals generated by donor innate immune cells can enhance engraftment and hematopoietic reconstitution during HSCT, which is particularly critical when limited HSC numbers are available and the risk of engraftment failure is high.
Assuntos
Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/imunologia , Interferon gama/imunologia , Células Matadoras Naturais/imunologia , Doadores de Tecidos , Animais , Proteínas Estimuladoras de Ligação a CCAAT/genética , Proteínas Estimuladoras de Ligação a CCAAT/imunologia , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Células Cultivadas , Técnicas de Cocultura , Perfilação da Expressão Gênica/métodos , Sobrevivência de Enxerto/genética , Sobrevivência de Enxerto/imunologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Interferon gama/genética , Interferon gama/metabolismo , Células Matadoras Naturais/metabolismo , Depleção Linfocítica/métodos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Camundongos TransgênicosRESUMO
Hematopoietic stem cells (HSCs) are capable of entering the cell cycle to replenish the blood system in response to inflammatory cues; however, excessive proliferation in response to chronic inflammation can lead to either HSC attrition or expansion. The mechanism(s) that limit HSC proliferation and expansion triggered by inflammatory signals are poorly defined. Here, we show that long-term HSCs (HSCLT) rapidly repress protein synthesis and cell cycle genes following treatment with the proinflammatory cytokine interleukin (IL)-1. This gene program is associated with activation of the transcription factor PU.1 and direct PU.1 binding at repressed target genes. Notably, PU.1 is required to repress cell cycle and protein synthesis genes, and IL-1 exposure triggers aberrant protein synthesis and cell cycle activity in PU.1-deficient HSCs. These features are associated with expansion of phenotypic PU.1-deficient HSCs. Thus, we identify a PU.1-dependent mechanism triggered by innate immune stimulation that limits HSC proliferation and pool size. These findings provide insight into how HSCs maintain homeostasis during inflammatory stress.