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Item Alkynyl nicotinamides show antileukemic activity in drug-resistant acute myeloid leukemia(The American Society for Clinical Investigation, 2024-06-17) Ramdas, Baskar; Dayal, Neetu; Pandey, Ruchi; Larocque, Elizabeth; Kanumuri, Rahul; Pasupuleti, Santhosh Kumar; Liu, Sheng; Kanellopoulou, Chrysi; Chu, Elizabeth Fei Yin; Mohallem, Rodrigo; Virani, Saniya; Chopra, Gaurav; Aryal, Uma K.; Lapidus, Rena; Wan, Jun; Emadi, Ashkan; Haneline, Laura S.; Holtsberg, Frederick W.; Aman, M. Javad; Sintim, Herman O.; Kapur, Reuben; Pediatrics, School of MedicineActivating mutations of FLT3 contribute to deregulated hematopoietic stem and progenitor cell (HSC/Ps) growth and survival in patients with acute myeloid leukemia (AML), leading to poor overall survival. AML patients treated with investigational drugs targeting mutant FLT3, including Quizartinib and Crenolanib, develop resistance to these drugs. Development of resistance is largely due to acquisition of cooccurring mutations and activation of additional survival pathways, as well as emergence of additional FLT3 mutations. Despite the high prevalence of FLT3 mutations and their clinical significance in AML, there are few targeted therapeutic options available. We have identified 2 novel nicotinamide-based FLT3 inhibitors (HSN608 and HSN748) that target FLT3 mutations at subnanomolar concentrations and are potently effective against drug-resistant secondary mutations of FLT3. These compounds show antileukemic activity against FLT3ITD in drug-resistant AML, relapsed/refractory AML, and in AML bearing a combination of epigenetic mutations of TET2 along with FLT3ITD. We demonstrate that HSN748 outperformed the FDA-approved FLT3 inhibitor Gilteritinib in terms of inhibitory activity against FLT3ITD in vivo.Item B cell–activating factor modulates the factor VIII immune response in hemophilia A(American Society for Clinical Investigation, 2021-04-15) Doshi, Bhavya S.; Rana, Jyoti; Castaman, Giancarlo; Shaheen, Mostafa A.; Kaczmarek, Radoslaw; Butterfield, John S.S.; Meeks, Shannon L.; Leissinger, Cindy; Biswas, Moanaro; Arruda, Valder R.; Pediatrics, School of MedicineInhibitors of factor VIII (FVIII) remain the most challenging complication of FVIII protein replacement therapy in hemophilia A (HA). Understanding the mechanisms that guide FVIII-specific B cell development could help identify therapeutic targets. The B cell–activating factor (BAFF) cytokine family is a key regulator of B cell differentiation in normal homeostasis and immune disorders. Thus, we used patient samples and mouse models to investigate the potential role of BAFF in modulating FVIII inhibitors. BAFF levels were elevated in pediatric and adult HA inhibitor patients and decreased to levels similar to those of noninhibitor controls after successful immune tolerance induction (ITI). Moreover, elevations in BAFF levels were seen in patients who failed to achieve FVIII tolerance with anti-CD20 antibody–mediated B cell depletion. In naive HA mice, prophylactic anti-BAFF antibody therapy prior to FVIII immunization prevented inhibitor formation and this tolerance was maintained despite FVIII exposure after immune reconstitution. In preimmunized HA mice, combination therapy with anti-CD20 and anti-BAFF antibodies dramatically reduced FVIII inhibitors via inhibition of FVIII-specific plasma cells. Our data suggest that BAFF may regulate the generation and maintenance of FVIII inhibitors and/or anti-FVIII B cells. Finally, anti-CD20/anti-BAFF combination therapy may be clinically useful for ITI.Item Barriers to mental health service use among hematopoietic SCT survivors(Springer, 2010) Mosher, C.E.; Duhamel, K.N.; Rini, C.M.; Li, Y.; Isola, L.; Labay, L.; Rowley, S.; Papadopoulos, E.; Moskowitz, C.; Scigliano, E.; Grosskreutz, C.; Redd, W.H.This study examined barriers to mental health service use and the demographic, medical and psychosocial correlates of these barriers among hematopoietic SCT (HSCT) survivors. A sample of 253 HSCT survivors who were 1 to 3 years posttransplant completed measures of demographic, physical, psychological and social characteristics as well as a newly modified measure of barriers to mental health service use. Only 50% of distressed HSCT survivors had received mental health services. An exploratory factor analysis of the barriers to mental health service use scale yielded four factors: scheduling barriers, knowledge barriers, emotional barriers and illness-related barriers. Patients with higher social constraints (perceived problems discussing the illness experience with significant others) reported higher levels of all four types of barriers. General distress and transplant-related posttraumatic stress symptoms were positively associated with emotional, knowledge and illness-related barriers to mental health service use, whereas physical and functional well-being were inversely associated with these barriers. Having more knowledge barriers and more emotional barriers predicted a lower likelihood of receiving mental health services, as did lower levels of education and general distress. Results suggest that a significant number of HSCT survivors may benefit from education about mental health services that is tailored to individual barriers.Item Combined heterozygosity of FLT3 ITD, TET2, and DNMT3A results in aggressive leukemia(The American Society for Clinical Investigation, 2022-09-08) Ramdas, Baskar; Reddy, Palam Lakshmi; Mali, Raghuveer Singh; Pasupuleti, Santhosh Kumar; Zhang, Ji; Kelley, Mark R.; Paczesny, Sophie; Zhang, Chi; Kapur, Reuben; Pediatrics, School of MedicineHeterozygous mutations in FLT3ITD, TET2, and DNMT3A are associated with hematologic malignancies in humans. In patients, cooccurrence of mutations in FLT3ITD combined with TET2 (TF) or FLT3ITD combined with DNMT3A (DF) are frequent. However, in some rare complex acute myeloid leukemia (AML), all 3 mutations cooccur - i.e., FLT3ITD, TET2, and DNMT3A (TFD). Whether the presence of these mutations in combination result in quantitative or qualitative differences in disease manifestation has not been investigated. We generated mice expressing heterozygous Flt3ITD and concomitant for either heterozygous loss of Tet2 (TF) or Dnmt3a (DF) or both (TFD). TF and DF mice did not induce disease early on, in spite of similar changes in gene expression; during the same time frame, an aggressive form of transplantable leukemia was observed in TFD mice, which was mostly associated with quantitative but not qualitative differences in gene expression relative to TF or DF mice. The gene expression signature of TFD mice showed remarkable similarity to the human TFD gene signature at the single-cell RNA level. Importantly, TFD-driven AML responded to a combination of drugs that target Flt3ITD, inflammation, and methylation in a mouse model, as well as in a PDX model of AML bearing 3 mutations.Item DEK Protein as a Potential Radio-protective Agent for Hematopoietic Stem Cells (HSCs) and Hematopoietic Progenitor Cells (HPCs) in Mice(2018-07-26) Sharma, Itee; Broxmeyer, Hal E.; Edward, Srour F.; Dent, Alexander; Orschell, ChristieStudies performed by our lab have investigated the potential radioprotective effect of rDEK protein. Although roles played by DEK in cell differentiation, DNA repair, DNA binding, chromatin regulating and different malignancies have been investigated previously in different cell types, the prospect of DEK being used as a potential radioprotective agent for HSCs has not yet been explored. In this study, using primary cells isolated from bone marrow of C57BL/6 mice in vitro, our data indicated that rDEK has the ability to act as potential radioprotector of HSC. Moreover, a significant decrease in percentages of caspase-3 and caspase-9 protease enzymes was observed after irradiation in presence of rDEK. Taken, together the data suggests that DEK imparts its effect as a potential radioprotective agent, via inhibiting the caspase-dependent intrinsic apoptosis pathway. We found no evidence that DEK could act as a radiomitigator but this was not tested in primary cells as well as in animals.Item FANCA maintains genomic stability through regulating BUBR1 acetylation(2017-08) Abdul Sater, Zahi Abass; Nalepa, Grzegorz; Clapp, Wade; Goebl, Mark; Wek, RonaldFanconi Anemia (FA), a chromosomal instability syndrome, is characterized by bone marrow failure, genetic malformations, and predisposition to malignancies like acute myeloid leukemia (AML) and solid tumors. FA is caused by germline bi-allelic mutations in one of 21 known FA pathway genes and somatic mutations in FA genes are also found in a variety of sporadic cancers. Recently, numerous reports have discovered that the protective function of the FA pathway extends beyond its canonical role in regulation of DNA repair in interphase. In particular, the FA pathway has been shown to function in essential mitotic processes including spindle assembly checkpoint (SAC), cytokinesis, and centrosome maintenance. Understanding of the mechanistic origins of genomic instability leading to carcinogenesis and bone marrow failure has important scientific and clinical implications. To this end, using a micronucleus assay, we showed that both interphase DNA damage and mitotic errors contribute to genomic instability in FA ex vivo and in vivo. Functional studies of primary FA patient cells coupled with super-resolution microscopy revealed that FANCA is important for centrosome dependent spindle assembly supporting the protective role of FA pathway in mitotic processes. Furthermore, we dissected the interactions between the FA pathway and cellular kinase networks by employing a synthetic lethality sh-RNA screen targeting all human kinases. We mapped kinases that were synthetically lethal upon loss of FANCA, particularly those involved in highly conserved signal transduction pathways governing proliferation and cell cycle homeostasis. We mechanistically show that loss of FANCA, the most abundant FA subtype, results in in premature degradation of the mitotic kinase BUBR1 and faster mitotic exit. We further demonstrate that FANCA is important for PCAF-dependent acetylation of BUBR1 to prevent its premature degradation. Our results deepen our understanding of the molecular functions of the FA pathway in mitosis and uncover a mechanistic connection between FANCA and SAC phosphosignaling networks. These findings support the notion that further weakening the SAC through targeting kinases like BUBR1 in FA-deficient cancers may prove to be a rational therapeutic strategy.Item Hyperglycemia cooperates with Tet2 heterozygosity to induce leukemia driven by proinflammatory cytokine–induced lncRNA Morrbid(American Society for Clinical Investigation, 2021-01-04) Cai, Zhigang; Lu, Xiaoyu; Zhang, Chi; Nelanuthala, Sai; Aguilera, Fabiola; Hadley, Abigail; Ramdas, Baskar; Fang, Fang; Nephew, Kenneth; Kotzin, Jonathan J.; Williams, Adam; Henao-Mejia, Jorge; Haneline, Laura; Kapur, Reuben; Microbiology and Immunology, School of MedicineDiabetes mellitus (DM) is a risk factor for cancer. The role of DM-induced hyperglycemic (HG) stress in blood cancer is poorly understood. Epidemiologic studies show that individuals with DM are more likely to have a higher rate of mutations in genes found in pre-leukemic hematopoietic stem and progenitor cells (pre-LHSPCs) including TET2. TET2-mutant pre-LHSPCs require additional hits to evolve into full-blown leukemia and/or an aggressive myeloproliferative neoplasm (MPN). Intrinsic mutations have been shown to cooperate with Tet2 to promote leukemic transformation. However, the extrinsic factors are poorly understood. Using a mouse model carrying Tet2 haploinsufficiency to mimic the human pre-LHSPC condition and HG stress, in the form of an Ins2Akita/+ mutation, which induces hyperglycemia and type 1 DM, we show that the compound mutant mice developed a lethal form of MPN and/or acute myeloid leukemia (AML). RNA-Seq revealed that this was due in part to upregulation of proinflammatory pathways, thereby generating a feed-forward loop, including expression of the antiapoptotic, long noncoding RNA (lncRNA) Morrbid. Loss of Morrbid in the compound mutants rescued the lethality and mitigated MPN/AML. We describe a mouse model for age-dependent MPN/AML and suggest that hyperglycemia acts as an environmental driver for myeloid neoplasms, which could be prevented by reducing expression levels of the inflammation-related lncRNA Morrbid.Item Loss of epigenetic regulator TET2 and oncogenic KIT regulate myeloid cell transformation via PI3K pathway(American Society for Clinical Investigation, 2018-02-22) Palam, Lakshmi Reddy; Mali, Raghuveer Singh; Ramdas, Baskar; Srivatsan, Sridhar Nonavinkere; Visconte, Valeria; Tiu, Ramon V.; Vanhaesebroeck, Bart; Roers, Axel; Gerbaulet, Alexander; Xu, Mingjiang; Janga, Sarath Chandra; Takemoto, Clifford M.; Paczesny, Sophie; Kapur, Reuben; Pediatrics, School of MedicineMutations in KIT and TET2 are associated with myeloid malignancies. We show that loss of TET2-induced PI3K activation and -increased proliferation is rescued by targeting the p110α/δ subunits of PI3K. RNA-Seq revealed a hyperactive c-Myc signature in Tet2-/- cells, which is normalized by inhibiting PI3K signaling. Loss of TET2 impairs the maturation of myeloid lineage-derived mast cells by dysregulating the expression of Mitf and Cebpa, which is restored by low-dose ascorbic acid and 5-azacytidine. Utilizing a mouse model in which the loss of TET2 precedes the expression of oncogenic Kit, similar to the human disease, results in the development of a non-mast cell lineage neoplasm (AHNMD), which is responsive to PI3K inhibition. Thus, therapeutic approaches involving hypomethylating agents, ascorbic acid, and isoform-specific PI3K inhibitors are likely to be useful for treating patients with TET2 and KIT mutations.Item Mice expressing KrasG12D in hematopoietic multipotent progenitor cells develop neonatal myeloid leukemia(American Society for Clinical Investigation, 2017-10-02) Tarnawsky, Stefan P.; Kobayashi, Michihiro; Chan, Rebecca J.; Yoder, Mervin C.; Biochemistry and Molecular Biology, School of MedicineJuvenile myelomonocytic leukemia (JMML) is a pediatric myeloproliferative neoplasm that bears distinct characteristics associated with abnormal fetal development. JMML has been extensively modeled in mice expressing the oncogenic KrasG12D mutation. However, these models have struggled to recapitulate the defining features of JMML due to in utero lethality, nonhematopoietic expression, and the pervasive emergence of T cell acute lymphoblastic leukemia. Here, we have developed a model of JMML using mice that express KrasG12D in multipotent progenitor cells (Flt3Cre+ KrasG12D mice). These mice express KrasG12D in utero, are born at normal Mendelian ratios, develop hepatosplenomegaly, anemia, and thrombocytopenia, and succumb to a rapidly progressing and fully penetrant neonatal myeloid disease. Mutant mice have altered hematopoietic stem and progenitor cell populations in the BM and spleen that are hypersensitive to granulocyte macrophage-CSF due to hyperactive RAS/ERK signaling. Biased differentiation in these progenitors results in an expansion of neutrophils and DCs and a concomitant decrease in T lymphocytes. Flt3Cre+ KrasG12D fetal liver hematopoietic progenitors give rise to a myeloid disease upon transplantation. In summary, we describe a KrasG12D mouse model that reproducibly develops JMML-like disease. This model will prove useful for preclinical drug studies and for elucidating the developmental origins of pediatric neoplasms.Item Mitigating oxygen stress enhances aged mouse hematopoietic stem cell numbers and function(American Society for Clinical Investigation, 2021-01-04) Capitano, Maegan L.; Mohamad, Safa F.; Cooper, Scott; Guo, Bin; Huang, Xinxin; Gunawan, Andrea M.; Sampson, Carol; Ropa, James; Srour, Edward F.; Orschell, Christie M.; Broxmeyer, Hal E.; Microbiology and Immunology, School of MedicineBone marrow (BM) hematopoietic stem cells (HSCs) become dysfunctional during aging (i.e., they are increased in number but have an overall reduction in long-term repopulation potential and increased myeloid differentiation) compared with young HSCs, suggesting limited use of old donor BM cells for hematopoietic cell transplantation (HCT). BM cells reside in an in vivo hypoxic environment yet are evaluated after collection and processing in ambient air. We detected an increase in the number of both young and aged mouse BM HSCs collected and processed in 3% O2 compared with the number of young BM HSCs collected and processed in ambient air (~21% O2). Aged BM collected and processed under hypoxic conditions demonstrated enhanced engraftment capability during competitive transplantation analysis and contained more functional HSCs as determined by limiting dilution analysis. Importantly, the myeloid-to-lymphoid differentiation ratio of aged BM collected in 3% O2 was similar to that detected in young BM collected in ambient air or hypoxic conditions, consistent with the increased number of common lymphoid progenitors following collection under hypoxia. Enhanced functional activity and differentiation of old BM collected and processed in hypoxia correlated with reduced “stress” associated with ambient air BM collection and suggests that aged BM may be better and more efficiently used for HCT if collected and processed under hypoxia so that it is never exposed to ambient air O2.