Hematopoietic Differentiation Research Articles

AI-based image classification algorithms for Leukaemia diagnostics and hematologic cytomorphology: From single cells to molecular features

Due to the progress of image analysis and classification systems in recent years, algorithms have been developed that support morphologic examination of both single cells and tissue samples. These algorithms are typically developed using data-driven strategies, which require comprehensive, large-scale datasets. In the diagnostic workup of hematopoietic malignancies, cytomorphologic examination and differentiation represents a key first step. In recent years, the availability of large-scale, high-quality datasets of single leukocytes from peripheral blood and bone marrow has led to the development of diagnostic support algorithms for this modality. These methods not only allow a faster and more consistent classification of diagnostically relevant cell types, but also pave the way for integrated analysis of cytomorphologic and molecular findings.

Emerging DNA Methylome Targets in FLT3-ITD-Positive Acute Myeloid Leukemia: Combination Therapy with Clinically Approved FLT3 Inhibitors.

The internal tandem duplication (ITD) mutation of the FMS-like receptor tyrosine kinase 3 (FLT3-ITD) is the most common mutation observed in approximately 30% of acute myeloid leukemia (AML) patients. It represents poor prognosis due to continuous activation of downstream growth-promoting signaling pathways such as STAT5 and PI3K/AKT. Hence, FLT3 is considered an attractive druggable target; selective small FLT3 inhibitors (FLT3Is), such as midostaurin and quizartinib, have been clinically approved. However, patients possess generally poor remission rates and acquired resistance when FLT3I used alone. Various factors in patients could cause these adverse effects including altered epigenetic regulation, causing mainly abnormal gene expression patterns. Epigenetic modifications are required for hematopoietic stem cell (HSC) self-renewal and differentiation; however, critical driver mutations have been identified in genes controlling DNA methylation (such as DNMT3A, TET2, IDH1/2). These regulators cause leukemia pathogenesis and affect disease diagnosis and prognosis when they co-occur with FLT3-ITD mutation. Therefore, understanding the role of different epigenetic alterations in FLT3-ITD AML pathogenesis and how they modulate FLT3I's activity is important to rationalize combinational treatment approaches including FLT3Is and modulators of methylation regulators or pathways. Data from ongoing pre-clinical and clinical studies will further precisely define the potential use of epigenetic therapy together with FLT3Is especially after characterized patients' mutational status in terms of FLT3 and DNA methlome regulators.

OGT and OGA gene-edited human induced pluripotent stem cells for dissecting the functional roles of O-GlcNAcylation in hematopoiesis.

Hematopoiesis continues throughout life to produce all types of blood cells from hematopoietic stem cells (HSCs). Metabolic state is a known regulator of HSC self-renewal and differentiation, but whether and how metabolic sensor O-GlcNAcylation, which can be modulated via an inhibition of its cycling enzymes O-GlcNAcase (OGA) and O-GlcNAc transferase (OGT), contributes to hematopoiesis remains largely unknown. Herein, isogenic, single-cell clones of OGA-depleted (OGAi) and OGT-depleted (OGTi) human induced pluripotent stem cells (hiPSCs) were successfully generated from the master hiPSC line MUSIi012-A, which were reprogrammed from CD34+ hematopoietic stem/progenitor cells (HSPCs) containing epigenetic memory. The established OGAi and OGTi hiPSCs exhibiting an increase or decrease in cellular O-GlcNAcylation concomitant with their loss of OGA and OGT, respectively, appeared normal in phenotype and karyotype, and retained pluripotency, although they may favor differentiation toward certain germ lineages. Upon hematopoietic differentiation through mesoderm induction and endothelial-to-hematopoietic transition, we found that OGA inhibition accelerates hiPSC commitment toward HSPCs and that disruption of O-GlcNAc homeostasis affects their commitment toward erythroid lineage. The differentiated HSPCs from all groups were capable of giving rise to all hematopoietic progenitors, thus confirming their functional characteristics. Altogether, the established single-cell clones of OGTi and OGAi hiPSCs represent a valuable platform for further dissecting the roles of O-GlcNAcylation in blood cell development at various stages and lineages of blood cells. The incomplete knockout of OGA and OGT in these hiPSCs makes them susceptible to additional manipulation, i.e., by small molecules, allowing the molecular dynamics studies of O-GlcNAcylation.

Low Initial Cell Density Promotes the Differentiation and Maturation of Human Pluripotent Stem Cells into Erythrocytes.

Human pluripotent stem cell (hPSC)-derived red blood cells (RBCs) possess great potential for compensating shortages in transfusion medicine. For better RBC generation from hPSCs, we compared the cell seeding density in the embryoid body formation-based hPSC induction protocol. In the selection of low- and high-density inoculation conditions, we found that low-density culture performed better in the final RBC product with more cell output and increased average cellular hemoglobin content. An elaborate study using flow cytometry demonstrated that low inoculation density promoted endothelial-to-hematopoietic transition, followed by improved hematopoietic progenitor formation and erythrocyte generation. The improved transformation from glycolysis to mitochondrial oxidation and reduced apoptosis might be responsible for this effect. Hints from RNA sequencing suggested that molecules involved in microenvironment interaction and metabolic regulation might respond for the different developmental potential. The possible mediators between outer message and intracellular response could be the nutrition sensors FOXO, PRKAA1 (AMPK), and MTOR genes. It is possible that low inoculation density triggered metabolic regulation signals, promoted mitochondrial oxidation, and resulted in enhanced cell amplification and hematopoietic differentiation. The low cell culture density will improve RBC generation from hPSCs.

The ATF4-RPS19BP1 axis modulates ribosome biogenesis to promote erythropoiesis

AbstractHematopoietic differentiation is controlled by intrinsic regulators and the extrinsic hematopoietic niche. Activating transcription factor 4 (ATF4) plays a crucial role in the function of fetal and adult hematopoietic stem cell maintenance. However, the precise function of ATF4 in the bone marrow (BM) niche and the mechanism by which ATF4 regulates adult hematopoiesis remain largely unknown. Here, we used 4 cell-type-specific mouse Cre lines to achieve conditional knockout of Atf4 in Cdh5+ endothelial cells, Prx1+ BM stromal cells, Osx+ osteoprogenitor cells, and Mx1+ hematopoietic cells and uncovered the role of Atf4 in niche cells and hematopoiesis. Intriguingly, depletion of Atf4 in niche cells did not affect hematopoiesis; however, Atf4-deficient hematopoietic cells exhibited erythroid differentiation defects, leading to hypoplastic anemia. Mechanistically, ATF4 mediated direct regulation of Rps19bp1 transcription, which is, in turn, involved in 40 S ribosomal subunit assembly to coordinate ribosome biogenesis and promote erythropoiesis. Finally, we demonstrate that under conditions of 5-fluorouracil–induced stress, Atf4 depletion impedes the recovery of hematopoietic lineages, which requires efficient ribosome biogenesis. Taken together, our findings highlight the indispensable role of the ATF4-RPS19BP1 axis in the regulation of erythropoiesis.

Analysis of blood methylation quantitative trait loci in East Asians reveals ancestry-specific impacts on complex traits.

Methylation quantitative trait loci (mQTLs) are essential for understanding the role of DNA methylation changes in genetic predisposition, yet they have not been fully characterized in East Asians (EAs). Here we identified mQTLs in whole blood from 3,523 Chinese individuals and replicated them in additional 1,858 Chinese individuals from two cohorts. Over 9% of mQTLs displayed specificity to EAs, facilitating the fine-mapping of EA-specific genetic associations, as shown for variants associated with height. Trans-mQTL hotspots revealed biological pathways contributing to EA-specific genetic associations, including an ERG-mediated 233 trans-mCpG network, implicated in hematopoietic cell differentiation, which likely reflects binding efficiency modulation of the ERG protein complex. More than 90% of mQTLs were shared between different blood cell lineages, with a smaller fraction of lineage-specific mQTLs displaying preferential hypomethylation in the respective lineages. Our study provides new insights into the mQTL landscape across genetic ancestries and their downstream effects on cellular processes and diseases/traits.

The DMT1 isoform lacking the iron-response element regulates normal and malignant hematopoiesis via NOTCH pathway activation.

Natural resistance-associated macrophage protein 2 (NRAMP 2; also known as DMT1 and encoded by SLC11A2) is mainly known for its iron transport activity. Recently, the DMT1 isoform lacking the iron-response element (nonIRE) was associated with aberrant NOTCH pathway activity. In this report, we investigated the function of DMT1 nonIRE in normal and malignant hematopoiesis. Knockdown of Dmt1 nonIRE in mice showed that it has non-canonical functions in hematopoietic stem cell differentiation: its knockdown suppressed development along the myeloid and lymphoid lineages, while promoting the production of platelets. These phenotypic effects on the hematopoietic system induced by Dmt1 nonIRE knockdown were linked to suppression of Notch/Myc pathway activity. Conversely, our data indicate a non-canonical function for DMT1 nonIRE overexpression in boosting NOTCH pathway activity in T-cell leukemia homeobox protein 1 (TLX1)-defective leukemia. This work sets the stage for future investigation using a multiple-hit T-cell acute lymphoblastic leukemia (T-ALL) model to further investigate the function of DMT1 nonIRE in T-ALL disease development and progression.

Abstract SY16-01: What IDH mouse models have taught us about hematological diseases, from leukemia to T cell lymphoma

Abstract SY16-01: What IDH mouse models have taught us about hematological diseases, from leukemia to T cell lymphoma

RIO-kinase 2 is essential for hematopoiesis.

Regulation of protein synthesis is a key factor in hematopoietic stem cell maintenance and differentiation. Rio-kinase 2 (RIOK2) is a ribosome biogenesis factor that has recently been described an important regulator of human blood cell development. Additionally, we have previously identified RIOK2 as a regulator of protein synthesis and a potential target for the treatment of acute myeloid leukemia (AML). However, its functional relevance in several organ systems, including normal hematopoiesis, is not well understood. Here, we investigate the consequences of RIOK2 loss on normal hematopoiesis using two different conditional knockout mouse models. Using competitive and non-competitive bone marrow transplantations, we demonstrate that RIOK2 is essential for the differentiation of hematopoietic stem and progenitor cells (HSPCs) as well as for the maintenance of fully differentiated blood cells in vivo as well as in vitro. Loss of RIOK2 leads to rapid death in full-body knockout mice as well as mice with RIOK2 loss specific to the hematopoietic system. Taken together, our results indicate that regulation of protein synthesis and ribosome biogenesis by RIOK2 is essential for the function of the hematopoietic system.

VEGFA, VEGFR1, VEGFR2 serum and cerebrospinal fluid concentration in patients with acute leukemia

Background. Vascular endothelial growth factor A (VEGFA) is one of the most important factors for regulation of hematopoietic stem cells differentiation. It is involved in leukemogenesis and central nervous system (CNS) damage in acute leukemia. According to the literature, the VEGFA production by blast cells is increased, but the values of serum concentration and the associations with CNS involvement are contradictory.Aim. evaluate the VEGFA, VEGFR1, VEGFR2 concentration in serum and cerebrospinal fluid of patient with different types of acute leukemia in disease onset and during treatment.Materials and methods. The concentration of VEGFA in serum and cerebrospinal fluid was studied in 74 primary patients with acute leukemia. The comparison group consisted of 67 healthy donors. VEGFR1, VEGFR2 were studied in serum and cerebrospinal fluid in 34 patients at the onset of the disease. The comparison group consisted of 10 healthy donors. For the analysis, an enzyme immunoassay was used on a semi-automatic Personal Lab analyzer (Adaltis) and Affymetrix eBioscience human VEGF-A Platinum ELISA reagents.Results. Serum VEGFA concentration was statistically significantly lower in acute leukemia patients than that of donors (median 149.78 and 432.19 pg/ml respectively; p <0.0001). Factor deficiency was significantly more pronounced in patients with blastemia (p <0.015). During antitumor therapy, there was a tendency to increase the amount of the factor in the blood serum. Serum concentration of soluble VEGFR2 was also lower in patients than that of donors (6949.9 and 8795.9 pg/ml respectively; p = 0.0026). For concentration of VEGFR1 such deviations were not found. The concentrations of VEGFR1 and VEGFR2 in serum were higher than in cerebrospinal fluid (p <0.0001), while VEGFR1 showed a positive correlation between serum and cerebrospinal fluid concentrations. the concentration of VEGFR1 in the cerebrospinal fluid was significantly lower in patients with B-lymphoblastic leukemia/lymphoma compared to other types of leukemia.Conclusion. the concentration of VEGFA in serum decreases in patients with blastemia, this may indicate a lack of secretion and excessive consumption of the factor by blast cells with a decrease in the proportion of leukocytes that normally secrete the factor. In the cerebrospinal fluid, the concentrations of VEGFR1 and VEGFR2 are lower than in serum, with the lowest values being found in patients with B-lymphoblastic leukemia/lymphoma, but no relationship with the development of CNS involvement was found.

Optimization of seeding density of OP9 cells to improve hematopoietic differentiation efficiency

BackgroundOP9 mouse stromal cell line has been widely used to induce differentiation of human embryonic stem cells (hESCs) into hematopoietic stem/progenitor cells (HSPCs). However, the whole co-culture procedure usually needs 14–18 days, including preparing OP9 cells at least 4 days. Therefore, the inefficient differentiation system is not appreciated. We aimed to optimize the culture conditions to improve differentiation efficiency.MethodsIn the experimental group, we set six different densities of OP9 cells and just cultured them for 24 h before co-culture, and in the control group, OP9 cells were cultured for 4 days to reach an overgrown state before co-culture. Then we compared the hematopoietic differentiation efficiency among them.ResultsOP9 cells were randomly assigned into two groups. In the experimental group, six different plated numbers of OP9 cells were cultured for 1 day before co-culture with hESCs. In contrast, in the control group, OP9 cells were cultured for 4 days at a total number of 3.1 × 104 cells/cm2 in a 6-well plate to reach an overgrown state before co-culture. Hematopoietic differentiation was evaluated with CD34 immunostaining, and compared between these two groups. We could not influence the differentiation efficiency of OP9 cells with a total number of 10.4 × 104 cells/cm2 in a 6-well plate which was cultured just for 1 day, followed by co-culture with hESCs. It reached the same differentiation efficiency 5 days earlier than the control group.ConclusionThe peak of CD34 + cells appeared 2 days earlier compared to the control group. A total number of 1.0 × 106 cells in a 6-well plate for OP9 cells was appropriate to have high differentiation efficiency.

Abstract 7224: Investigation of the efficacy of duocarmycin SA in combination with FDA approved drugs in acute myeloid leukemia cells in vitro

Abstract Acute myeloid leukemia (AML) is a hematological malignancy that is characterized by the arrest of hematopoietic stem cell differentiation, clonal expansion of myeloid hematopoietic precursors and poor patient survival outcomes. Despite therapeutic advancements, the prognosis of AML patients remains poor and improving patient survival outcomes continues to be a challenge. Therefore, the objective of this study was to investigate the efficacy of Duocarmycin SA (DSA- an antitumor antibiotic that induces DNA alkylation) in combination with FDA approved drugs currently used in the treatment of AML. In this study, DSA was evaluated in combination with doxorubicin (an anthracycline that disrupts topoisomerase II mediated DNA repair) or etoposide (a topoisomerase II inhibitor used to treat relapsed/refractory AML) in human AML cells in vitro. We hypothesized that DSA in combination with doxorubicin or etoposide would exhibit synergistic effects by improving the efficacy of both doxorubicin and etoposide in AML cells. The human AML cell lines (Molm-14 and HL60) were used for all studies. The phenotype of the cells was confirmed by flow cytometry and the IC50 of the drugs were determined using the MTT assay. Our results showed that the AML cells were CD45+, CD33+, CD13+ and CD4+. The IC50 of DSA alone for Molm-14 cells and HL60 cells were 11.12 pM and 114.8 pM, respectively. DSA alone induced DNA double-stranded breaks, significantly decreased the production of colonies and significantly increased apoptosis in AML cells in a dose-dependent manner. The IC50 of doxorubicin alone and etoposide alone was 68.6 nM and 129.7 nM, respectively. DSA in combination with the FDA approved AML drugs showed increased cytotoxic efficacy by observable decreases in AML cell viability. In summary, 1) picomolar concentrations of DSA alone was sufficient to significantly reduce AML cell viability; 2) DSA in combination with doxorubicin or etoposide significantly reduced AML cell viability and reduced the IC50 concentration of doxorubicin and etoposide. Thus, highlighting the therapeutic potential of using DSA in combination with doxorubicin or etoposide as a drug combination strategy to improve AML patient survival outcomes by decreasing the concentration of drugs necessary to treat patients and reducing off-target toxicity. Citation Format: William A. Chen, Diego Aguilar, Leena So, Yasmeen Jawhar, Nhi Nguyen, Natalie Drew, Terry G. Williams, Carlos A. Casiano, Sinisa Dovat, Kristopher Boyle, Olivia L. Francis-Boyle. Investigation of the efficacy of duocarmycin SA in combination with FDA approved drugs in acute myeloid leukemia cells in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7224.

Abstract 6407: Identification of novel chemotherapy-related CHIP variations in patients with high-grade serous ovarian cancer

Abstract Background: Hematopoietic lineage differentiation is subjected to genetic mutations that, due to fitness advantages, might give rise to clonally expanded populations. Clonal hematopoiesis of indeterminate potential (CHIP) is defined as the outgrowth of a single clone driven by acquired somatic mutations in hematopoietic stem cells (HSCs), in the absence of hematological abnormalities. Previous studies have shown the association of CH with aging and a higher risk of developing secondary hematologic malignancies in cancer patients treated with chemotherapy agents. It is therefore of great interest to study CH incidence prior to and post chemotherapy exposure and its association with the evolution of hematologic malignancies. We aimed to characterize CHIP variants of a highly selected group of patients with high-grade serous ovarian cancer (HGSC) who underwent neoadjuvant chemotherapy (NACT). Methods: Comprehensive ultra-high-depth whole exome sequencing, employing unique molecular barcode technologies, was performed using plasma-derived cell-free DNA (cfDNA) and matched white blood cells (WBC) DNA and tumor DNA from pre-NACT (n=10) and post-NACT (n=10) samples of patients with HGSC. CHIP variants were defined as heterozygous variants found in both the WBC and cfDNA samples from the same patients with variant allele frequency less than 5% in the WBC and higher than 0.5% in cfDNA samples. Results: Our analysis identified 93,088 variants, impacting 13,780 genes. Among them, 463 variants were already known and published, and 5,548 variants were common to the COSMIC genes signature. The number of CHIP variants significantly decreased after chemotherapy (p = 0.004). We then focused on CHIP variants enriched after chemotherapy and identified 77 that showed higher VAF in post-NACT cfDNA samples, which may be associated with the development of therapy-related acute myeloid leukemia/myelodysplastic syndrome (t-AML/MDS). Among them, interestingly, we found a missense mutation with protein change in CDK12 (chr17_39492765_G_T). We noticed that 38% of the CHIP variants found in cfDNA samples, were also found in matched tumor samples. Among these, another CDK12 missense mutation (chr17_39492768_A_T) showed higher VAF in post-NACT tumors. Conclusions: Our innovative approach detected a higher number of CHIP variants than currently characterized. Analysis of cfDNA from HGSC patients consistently demonstrated a reduction in CHIP mutations post-NACT. The subset of variants with increased VAF post-NACT may be associated with therapy-related t-AML/MDS. The detection of cfDNA CHIP variants in matched tumors highlights the potential predictive role of CHIP in t-AML/MDS development, emphasizing its consideration in therapeutic protocols. Citation Format: Sara Corvigno, Amma Asare, Jun Yao, Li Zhao, Nicole Fleming, Joseph Celestino, Richard A. Hajek, Ency A. Arboleda Goette, Ridge T. Rogers, Tri V. Nguyen, Raymond N. Montoya, Karen H. Lu, Amir A. Jazaeri, Shannon N. Westin, Anil K. Sood, Sanghoon Lee. Identification of novel chemotherapy-related CHIP variations in patients with high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6407.

Differentiation and Characterization of Osteoclasts from Human Induced Pluripotent Stem Cells.

This protocol details the propagation and passaging of human iPSCs and their differentiation into osteoclasts. First, iPSCs are dissociated into a single-cell suspension for further use in embryoid body induction. Following mesodermal induction, embryoid bodies undergo hematopoietic differentiation, producing a floating hematopoietic cell population. Subsequently, the harvested hematopoietic cells undergo a macrophage colony-stimulating factor maturation step and, finally, osteoclast differentiation. After osteoclast differentiation, osteoclasts are characterized by staining for TRAP in conjunction with a methyl green nuclear stain. Osteoclasts are observed as multinucleated, TRAP+ polykaryons. Their identification can be further supported by Cathepsin K staining. Bone and mineral resorption assays allow for functional characterization, confirming the identity of bona fide osteoclasts. This protocol demonstrates a robust and versatile method to differentiate human osteoclasts from iPSCs and allows for easy adoption in applications requiring large quantities of functional human osteoclasts. Applications in the areas of bone research, cancer research, tissue engineering, and endoprosthesis research could be envisioned.

Abstract 2778: Influence of the differentiation strategy on the phenotypic and genotypic features of iPSC derived NK cells

Abstract The iPSC-derived NK (iNK) cells offer new perspectives to produce large-scale of homogeneous immunotherapeutic cellular products and open the way towards manufacturing off-the-shelf cancer immunotherapies. Numerous strategies and protocols of differentiation of iPSCs toward NK lineage have been published in the last decade. Nevertheless, the embryological development of the NK cells and the impact of the differentiation strategy on the activity of the NK cells are still not clearly understood. Furthermore, very few studies have compared different NK differentiation strategies from iPSC. this study, we compared two previously reported protocols for NK cell generation from the same iPSC line, one feeder-based and the other feeder-free. In the first protocol, 3D hematopoietic differentiation was followed by lymphoid differentiation, using an OP9 DLL4 expressing feeder cell line. The second protocol employed a clinical-grade approach, utilizing the “spin embryoid body” method to generate primitive hematopoietic progenitors. Subsequently, these progenitors were differentiated towards the NK lineage in a feeder-free environment. Hematopoietic progenitors produced by these protocols have distinct phenotypes, suggesting variations in their maturity levels. Furthermore, the protocols have different kinetics of differentiation revealed by CD56 and CD7 phenotypes. Although, both protocols were able to efficiently generate functional and mature NK cells, characterized by the expression of activating and maturity ligands but with a distinct transcriptomic profile. iNK cells generated using feeders exhibit a more pronounced inflammatory profile with the expression of hallmark NFKB and STAT3 signaling pathways. In contrast, feeder-free iNK cells have a more proliferative profile as evidenced by increased expression of cell cycle factors such as E2F or Myc. Feeder-based iNK cells exhibit increased expression of transcription factors involved in NK cell differentiation, such as GATA2, STAT1, and IRF1. These transcriptional variances are reinforced by superior functionality observed in feeder-based NK cells compared to feeder-free NK cells, evidenced by increased degranulation (p-value < 0.0001) and cytotoxicity (p-value = 0.0004) at a 1:2 (effector-to-target) ratio against the K562 cell line. Our findings indicate that, despite the advantages of the feeder-free strategy, the feeder-based protocol remains more efficient and produces iPSC-derived NK cells with an enhanced cytotoxic profile in vitro. Our comprehensive transcriptional analysis offers significant insights into the biological and functional properties of iNK cells. This information has the potential to oncover novel mechanisms for NK differentiation strategies from iPSCs. Citation Format: Matthias Huyghe, Christophe Desterke, Jusuf Imeri, Nathan Belliard, Ali G. Turhan, Annelise Bennaceur Griscelli, Frank Griscelli. Influence of the differentiation strategy on the phenotypic and genotypic features of iPSC derived NK cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2778.

Abstract 294: The HOXB7 protein promotes breast cancer cell growth through activation of the CCL5/CCR5 pathway in the crosstalk of adipocyte

Abstract Homeobox genes are regulatory genes that encode nuclear proteins acting as transcription factors during normal development and differentiation. One such gene, HOXB7, plays a role in various developmental processes, including hematopoietic differentiation, lymphoid development, and mammary gland development. However, the role of HOX genes in breast cancer development remains largely unexplored. Our previous studies revealed that HOXB7 expression was significantly elevated in primary cancer and distant metastasis. HOXB7 overexpression promoted cell proliferation in SKBR3 breast cancer cells, leading to robustly vascularized xenografts in immunodeficient mice. Furthermore, HOXB7 enhanced tumor growth through TGF beta signaling and recruitment of macrophages, indicating the role of HOXB7 in the crosstalk of stromal components. We found evidence that HOXB7 overexpression in ER+ breast cancer cells promotes tumor cell growth through increased expression and signaling of CCL5/CCR5 in crosstalk with adipocytes. By screening secreted factors in adipocytes induced by TCM of MCF-7-HOXB7 cells, it was also found that CCL5 is highly expressed in HOXB7-overexpressing MCF-7 cells. The CCR5 inhibitor, maraviroc, sensitized MCF-7-HOXB7 cells compared to control cells. These findings suggest that blocking the interaction between CCL5 and CCR5 signaling significantly inhibits ER+ breast cancer with HOXB7 overexpression. We aim to further investigate if HOXB7 overexpression in ER+ breast cancer cells promotes tumor cell growth through increased expression and signaling of CCL5/CCR5 in crosstalk with adipocytes and the role of CCL5 in breast cancer cell growth and migration. Citation Format: Ahone Gina Akume, Kideok Jin. The HOXB7 protein promotes breast cancer cell growth through activation of the CCL5/CCR5 pathway in the crosstalk of adipocyte [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 294.

Abstract 141: A human induced pluripotent stem cell model of KMT2A rearranged leukemia

Abstract Acute lymphoblastic leukemia in infants (iALL) is a high-risk subtype of childhood leukemia with poor survival outcomes despite intensive therapies. Rearrangement of KMT2A (KMT2A-r) occurs in 70% of cases and is associated with refractoriness to therapy, early relapse, and rapid leukemia progression. KMT2A-r generates a driver fusion oncogene, most commonly KMT2A::AFF1 in iALL, which leads to epigenetic dysregulation of target gene transcription. iALL with KMT2A::AFF1 is an unusual cancer in that other somatic mutations are uncommon, there are no known genetic risk factors, and phenotypic switch from lymphoid to myeloid, mixed, or undifferentiated phenotype is common during treatment and particularly resistant to therapies. The cell of origin is thought to be a very early hematopoietic precursor, with transcriptomic studies of iALL blasts showing similarities to hematopoietic stem and progenitor cells (HSPCs), multipotent progenitors and early lymphoid progenitors (ELPs). Unfortunately, research into this rare but devastating disease has been hindered by a lack of appropriate, representative models. Interestingly, KMT2A-r originates in HSPCs in utero and the age of onset of iALL is a strong prognostic factor, with age younger than six months associated with the highest risk of relapse. However, little is known regarding how KMT2A-r subverts early hematopoiesis or drives the severe disease phenotype. In an effort to understand the role of the developmental state of the cell of origin in iALL, we have created a highly controlled induced pluripotent stem (iPS) cell model system of KMT2A::AFF1 leukemia. Specifically, we engineered human iPS cell lines with doxycycline regulatable expression of KMT2A::AFF1 fusion and we are employing CRISPR gene editing technology to introduce clinically identified variants of interest. Utilizing directed differentiation, we have produced functional HSPCs from iPS cells. Notably, this model recapitulates hematopoietic ontogeny, with the ability to control iALL induction at specific developmental stages. Following doxycycline treatment, we demonstrate that the cells express KMT2A::AFF1 fusion transcripts. We are utilizing single cell genomics to investigate transcriptomic changes during hematopoietic differentiation of our KMT2A::AFF1 iPS cells. We will compare these results to published data sets of single cell RNA sequencing data from healthy fetal HSPCs and to our existing iALL and pediatric KMT2A-r ALL single cell sequencing data sets. Our iPS cell based iALL model system provides the opportunity to investigate a range of critical and outstanding questions of iALL disease initiation, progression, and treatment. Citation Format: Erin Guest, Meagan Vacek, Jacqelyn Nemechek, Irina Pushel, Bradley T. Thornton, Molly Leyda, Midhat S. Farooqi, John M. Perry, Jay L. Vivian. A human induced pluripotent stem cell model of KMT2A rearranged leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 141.

Clinical and prognostic significance of baseline microRNA 223 in acute ischemic stroke

BackgroundAcute ischemic stroke (AIS) is the second leading cause of disability and death worldwide. Micro-RNA (miRNA)-223 was first identified as a regulator of hematopoietic lineage differentiation. Later, its diverse roles were discovered in a wide spectrum of pathological conditions. The present study aimed to assess the clinical and prognostic significance of miR-223 in patients with acute ischemic stroke (AIS). The study included 93 patients with AIS diagnosed on the basis of clinical and radiological findings. In addition, there were 50 healthy subjects who served as controls. Patients were classified into two categories: Those with favorable functional outcome (modified Rankin Scale (mRS): 0–2) and others with unfavorable functional outcome (mRS: 3–6) at 6 months post-stroke.ResultsThe present prospective longitudinal study included 93 patients with AIS. They included 60 males (64.5%) and 33 females (35.5%) with an age of 64.5 ± 12.4 years. At the end of 6-month follow up, 44 patients (47.3%) had favorable outcome while the remainder 49 patients (52.7%) had unfavorable outcome. Patients with favorable outcome had significantly lower baseline miR-223 levels [median (IQR): 4.4 (2.0–6.3) versus 8.4 (4.5–14.9), p < 0.001], lower HbA1c levels (5.6 ± 1.0 versus 6.2 ± 1.2, p = 0.006) and lower C-reactive protein (CRP) levels [median (IQR): 8.9 (5.1–26.7) versus 15.2 (6.2–39.3) mg/dL, p = 0.02]. Multivariate binary logistic regression analysis recognized high baseline miR-223 [OR (95% CI) 1.13 (1.06–1.24), p = 0.011], infarct size [OR (95% CI) 2.58 (1.66–4.77), p = 0.001] and National Institutes of Health Stroke Scale (NIHSS) [OR (95% CI) 2.11 (1.74–3.09), p = 0.004] as significant predictors of unfavorable outcome in the studied patients.ConclusionsElevated baseline miR-223 levels are associated with high NIHSS and larger infarct size at baseline and can effectively predict patients’ outcome at 6-months post-stroke.

PHF19 before and post induction treatment possess favorable potency of reflecting treatment response to protease inhibitors, event-free survival, and overall survival in multiple myeloma patients

ABSTRACT Objective Plant homeodomain finger protein 19 (PHF19) regulates hematopoietic stem cell differentiation and promotes multiple myeloma (MM) progression. This study intended to explore the potency of PHF19 at baseline and post induction treatment in estimating treatment response to protease inhibitors and survival in MM patients. Methods This retrospective study screened 69 MM patients who received protease inhibitors with bone marrow (BM) samples available at both baseline and post induction treatment. Twenty healthy BM donors were included as healthy controls (HCs). PHF19 in plasma cells from BM was quantified by reverse transcription-quantitative polymerase chain reaction. Results PHF19 at baseline and post induction treatment in MM patients were increased than in HCs. In MM patients, PHF19 was declined post induction treatment. Elevated PHF19 at baseline and post induction treatment were correlated with renal impairment, beta-2-microglobulin ≥5.5 mg/L, t (4; 14), higher international staging system (ISS) stage, and higher revised ISS (R-ISS) stage. Concerning treatment response, PHF19 at baseline and post induction treatment were negatively associated with complete response and overall response rate. Notably, abnormal PHF19 (above 95% quantile value of PHF19 in HCs) at baseline and post induction treatment were linked with shortened event-free survival (EFS) and overall survival (OS). After adjustment, abnormal PHF19 post induction treatment was independently related to shortened EFS (hazard ratio = 2.474) and OS (hazard ratio = 3.124). Conclusion PHF19 is aberrantly high and declines post induction therapy, which simultaneously reflects unfavorable treatment response to protease inhibitors as well as shorter EFS and OS in MM patients.

Autoantibodies-Abzymes with Phosphatase Activity in Experimental Autoimmune Encephalomyelitis Mice.

The exact mechanisms of MS (multiple sclerosis) evolution are still unknown. However, the development of EAE (experimental autoimmune encephalomyelitis simulating human MS) in C57BL/6 mice occurs due to the violation of bone marrow hematopoietic stem cell differentiation profiles, leading to the production of toxic for human autoantibody splitting MBP (myelin basic protein), MOG (mouse oligodendrocyte glycoprotein), five histones, DNA, and RNA. Here, we first analyzed the changes in the relative phosphatase activity of IgGs from C57BL/6 mice blood over time, corresponding to three stages of EAE: onset, acute, and remission. Antibodies have been shown to catalyze the hydrolysis of p-nitrophenyl phosphate at several optimal pH values, mainly in the range of 6.5-7.0 and 8.5-9.5. During the spontaneous development of EAE, the most optimal value is pH 6.5. At 50 days after the birth of mice, the phosphatase activity of IgGs at pH 8.8 is 1.6-fold higher than at pH 6.5. During spontaneous development of EAE from 50 to 100 days, an increase in phosphatase activity is observed at pH 6.5 but a decrease at pH 8.8. After mice were immunized with DNA-histone complex by 20 and 60 days, phosphatase activity increased respectively by 65.3 and 109.5 fold (pH 6.5) and 128.4 and 233.6 fold (pH 8.8). Treatment of mice with MOG at the acute phase of EAE development (20 days) leads to a maximal increase in the phosphatase activity of 117.6 fold (pH 6.5) and 494.7 fold (pH 8.8). The acceleration of EAE development after mice treatment with MOG and DNA-histone complex results in increased production of lymphocytes synthesizing antibodies with phosphatase activity. All data show that IgG phosphatase activity could be essential in EAE pathogenesis.