The RUNX1/ETO fusion protein is a chimeric transcription factor in acute myeloid leukemia (AML) created by chromosomal translocation t(8;21)(q22;q22). t(8;21) abnormality is associated with 12% of de novo AML cases and up to 40% in the AML subtype M2. Previously, we identified the small-molecule inhibitor 7.44, which interferes with NHR2 domain tetramerization of RUNX1/ETO, restores gene expression down-regulated by RUNX1/ETO, inhibits proliferation, and reduces RUNX1/ETO-related tumor growth in a mouse model. However, despite favorable properties, 7.44 is negatively charged at physiological pH and was predicted to have low to medium membrane permeability. Here, we identified M23, M27, and M10 as non-charged analogs of 7.44 using ligand-based virtual screening, in vivo hit identification, biophysical and in vivo hit validation, and integrative modeling and ADMET predictions. All three compounds interact with the NHR2 domain, have KD, app values of 39-114 µM in Microscale Thermophoresis experiments, and IC50 values of 33-77 µM as to cell viability in RUNX1/ETO-positive KASUMI cells, i.e., are ~ 5 to 10-fold more potent than 7.44. M23 is ~ 10-fold more potent than 7.44 in inhibiting cell proliferation of RUNX1/ETO-positive cells. Biological characterization of M23 in relevant RUNX1/ETO-positive -and negative cell lines indicates that M23 induces apoptosis and promotes differentiation in RUNX1/ETO-positive AML cells. M23 and M27 are negligibly protonated or in a ~ 1:1 ratio at physiological pH, while M10 has no (de-)protonatable group. The non-protonated species are predicted to be highly membrane-permeable, along with other favorable pharmacokinetic and toxicological properties. These compounds might serve as lead structures for compounds inhibiting RUNX1/ETO oncogenic function in t(8;21) AML.
© 2025. The Author(s).

Podocalyxin (PODXL), a cell surface sialomucin expressed in diverse types of normal and malignant cells, mediates cellular adhesion to extracellular matrix and cell-to-cell interaction. A previous study reported the expression of PODXL protein on monocytes undergoing macrophage differentiation, yet the expression of this molecule in other antigen presenting cells (APCs) and its function in the immune system still remain undetermined. In this study, we report that PODXL is expressed in human monocyte-derived immature dendritic cells at both the mRNA and protein levels. Following dendritric cells maturation using pro-inflammatory stimuli, PODXL expression level decreased substantially. Furthermore, we found that PODXL expression is positively regulated by IL-4 through MEK/ERK and JAK3/STAT6 signaling pathways. Our results revealed a polarized distribution of PODXL during the interaction of APCs with CD4+ T cells, partially colocalizing with F-actin. Notably, PODXL overexpression in APCs promoted their interaction with CD4+ T cells and CD8+ T cells and decreased the expression of MHC-I, MHC-II, and the costimulatory molecule CD86. In addition, PODXL reduced the translocation of CD4+ T-cell centrosome toward the APC-contact site. These findings suggest a regulatory role for PODXL expressed by APCs in immune responses, thus representing a potential target for therapeutic blockade in infection and cancer.
Copyright © 2022 Amo, Díez-García, Tamayo-Orbegozo, Maruri and Larrucea.

Staphylococcus aureus infections are a common concern world-wide due to the increasing number of bacterial strains with multiresistant properties to existing antibiotics, incrementing the need for novel molecules and therapy approaches for their treatment. This study evaluated the antibacterial and immunomodulatory activity of eight new peptides (AA, KS, NS, RN, AT, GF, KV and LK) as the basis for the search of new antibacterial and therapeutic agents for topic prevention and treatment against S. aureus infections. Here, there are characterized in silico eight new antimicrobial peptides. Their antibacterial activity against S. aureus and cytotoxic activity in mammalian cell lines were evaluated in vitro with the peptides individually and combined. Three of the peptides (GF, AT and AA) immunomodulatory activity was assessed in macrophages and under three scenarios: non-stimulation, Escherichia coli LPS stimulation and S. aureus lysate stimulation. Results showed that three peptides individually showed the best antibacterial activity against the S. aureus bacteria evaluated. The peptides presented immunomodulatory activity in THP-1 macrophages by displaying different profiles, increasing or decreasing four cytokines (IL-1β, TNF- α , IL-8 and CCL2 (MCP1)). This activity depended on the peptide concentration and the stimulation in which the macrophages were exposed to. Taken together, these results demonstrate the potential of these peptides to be used in further studies as novel antimicrobial molecules for the prevention and treatment of S. aureus infections.

The interactions of hematopoietic stem and progenitor cells (HSPCs) with extracellular matrix (ECM) components and cells from the bone marrow (BM) microenvironment control their homeostasis. Regenerative BM conditions can induce expression of the ECM protein transforming growth factor beta-induced gene H3 (TGFBI or BIGH3) in murine HSPCs. In this study, we examined how increased or reduced TGFBI expression in human HSPCs and BM mesenchymal stromal cells (MSCs) affects HSPC maintenance, differentiation, and migration. HSPCs that overexpressed TGFBI showed accelerated megakaryopoiesis, whereas granulocyte differentiation and proliferation of granulocyte, erythrocyte, and monocyte cultures were reduced. In addition, both upregulation and downregulation of TGFBI expression impaired HSPC colony-forming capacity of HSPCs. Interestingly, the colony-forming capacity of HSPCs with reduced TGFBI levels was increased after long-term co-culture with MSCs, as measured by long-term culture-colony forming cell (LTC-CFC) formation. Moreover, TGFBI downregulation in HSPCs resulted in increased cobblestone area-forming cell (CAFC) frequency, a measure for hematopoietic stem cell (HSC) capacity. Concordantly, TGFBI upregulation in HSPCs resulted in a decrease of CAFC and LTC-CFC frequency. These results indicate that reduced TGFBI levels in HSPCs enhanced HSC maintenance, but only in the presence of MSCs. In addition, reduced levels of TGFBI in MSCs affected MSC/HSPC interaction, as observed by an increased migration of HSPCs under the stromal layer. In conclusion, tight regulation of TGFBI expression in the BM niche is essential for balanced HSPC proliferation and differentiation.

Background: Central obesity (CO) is an inflammatory disease. Because immune cells and adipocytes are catecholamines(CA)-producing cells, we studied the expression of adrenoceptors (AR) in peripheral blood mononuclear cells (PBMCs) hypothesizing a distinct adrenergic pattern in inflammatory obesity. Methods: AR expression was assessed in blood donors categorized by waist circumference (WC) (CO: WC≥0.80 m in women and ≥0.94 m in men). Following a pilot study for all AR subtypes, we measured β2AR expression in fifty-seven individuals and correlated this result with anthropometric, metabolic and inflammatory parameters. A ratio (R) between AR mRNA of CO and non-CO<0.5 was considered under and >2.0 over expression. Results: The pilot study revealed no differences between groups, except for β2AR mRNA. CO individuals showed underexpression of β2AR relatively to those without CO (R=0.08; p=0.009). β2AR expression inversely correlated with triacylglycerol (r=-0.271; p=0.041), very low-density lipoprotein-cholesterol (r=-0.313; p=0.018) and leptin (r=-0.392; p=0.012) and positively with high-density lipoprotein-cholesterol (r=0.310: p=0.045) plasma levels. Multiple logistic regression analysis showed a protective effect of β2AR expression (≥2x10-6) [odds ratio (OR) 0.177 with respective confidence interval of 95% (95% CI) (0.040- 0.796)] for the occurrence of CO. A higher association was found for women as compared to men (Ξ9:1) [OR 8.972 (95% CI) (1.679-47.949)]. Conclusion: PBMCs β2AR, underexpressed in centrally obese, are associated with a better metabolic profile and showed a protective role for the development of CO. The discovery of β2AR as a new molecular marker of obesity subphenotypes in PBMCs might contribute to clarify the adrenergic immunomodulation of inflammatory obesity.