A highly potent small-molecule antagonist of exportin-1 selectively eliminates CD44+CD24- enriched breast cancer stem-like cells.

Breast cancer stem-like cells (BCSCs) have been suggested as the underlying cause of tumor recurrence, metastasis and drug resistance in triple-negative breast cancer (TNBC). Here, we report the discovery and biological evaluation of a highly potent small-molecule antagonist of exportin-1, LFS-1107. We ascertained that exportin-1 (also named as CRM1) is a main cellular target of LFS-1107 by nuclear export functional assay, bio-layer interferometry binding assay and C528S mutant cell line. We found that LFS-1107 significantly inhibited TNBC tumor cells at low-range nanomolar concentration and LFS-1107 can selectively eliminate CD44+CD24- enriched BCSCs. We demonstrated that LFS-1107 can induce the nuclear retention of Survivin and consequent strong suppression of STAT3 transactivation abilities and the expression of downstream stemness regulators. Administration of LFS-1107 can strongly inhibit tumor growth in mouse xenograft model and eradicate BCSCs in residual tumor tissues. Moreover, LFS-1107 can significantly ablate the patient-derived tumor organoids (PDTOs) of TNBC as compared to a few approved cancer drugs. Lastly, we revealed that LFS-1107 can enhance the killing effects of chemotherapy drugs and downregulate multidrug resistance related protein targets. These new findings provide preclinical evidence of defining LFS-1107 as a promising therapeutic agent to deplete BCSCs for the treatment of TNBC.

Targeted Intervention of NF2-YAP Signaling Axis in CD24-Overexpressing Cells Contributes to Encouraging Therapeutic Effects in TNBC.

Triple-negative breast cancer (TNBC) cells have not been usefully classified, and no targeted therapeutic plans are currently available, resulting in a high recurrence rate and metastasis potential. In this research, CD24high cells accounted for the vast majority of TNBC cells, and they were insensitive to Taxol but sensitive to ferroptosis agonists and effectively escaped phagocytosis by tumor-associated macrophages. Furthermore, the NF2-YAP signaling axis modulated the expression of ferroptosis suppressor protein 1 (FSP1) and CD24 in CD24high cells, with subsequent ferroptotic regulation and macrophage phagocytosis. In addition, a precision targeted therapy system was designed based on the pH level and glutathione response, and it can be effectively used to target CD24high cells to induce lysosomal escape and drug burst release through CO2 production, resulting in enhanced ferroptosis and macrophage phagocytosis through FSP1 and CD24 inhibition mediated by the NF2-YAP signaling axis. This system achieved dual antitumor effects, ultimately promoting cell death and thus inhibiting TNBC tumor growth, with some tumors even disappearing. The composite nanoprecision treatment system reported in this paper is a potential strategic tool for future use in the treatment of TNBC.

Tratamiento con EXO-CD24 para COVID-19 moderado/severo / EXO-CD24 treatment for moderate/severe COVID-19

ANTECEDENTES: Existe información periodística respecto a un nuevo tratamiento contra COVID-19 denominado EXO-CD24, que habría sido administrado en Israel a 30 participantes con COVID-19 moderado o severo, con una recuperación de 29 de ellos(1). El presente informe se realiza a solicitud de la Jefatura del INS, a fin de identificar si existen publicaciones científicas referentes a EXO-CD24. RESULTADOS: Los exosomas constituyen un tipo de vesícula extracelular que se origina a partir del sistema endosomal y tiene una estructura de membrana de bicapa lipídica. Su tamaño varía entre 30 y 150 nm de diámetro. Se le reconoce como un mecanismo de comunicación intercelular, transportando moléculas bioactivas como proteínas, lípidos, ARN, e incluso fragmentos de ADN entre células. Según sus diferentes orígenes celulares, los exosomas desempeñan funciones distintas en los procesos fisiológicos normales, como la respuesta inmune, la proliferación celular, la inflamación, el metabolismo y la función neuronal y en diferentes etapas de las enfermedades, incluido el cáncer. Se está investigando su potencial uso diagnóstico (biomarcadores) y como un sistema de administración terapéutica dadas las siguientes ventajas: 1) se consideran más seguros que la terapia celular porque son biocompatibles, no inmunogénicos y carecen del potencial de formación de tumores endógenos y émbolos. 2) Son fisiológicamente más estables que las células, porque sus proteínas de adhesión a múltiples membranas permiten una unión eficiente en los tejidos diana. 3) Gracias a su membrana resistente, los exosomas mantienen su integridad durante los procedimientos de congelación y descongelación, haciendo posible el almacenamiento a largo plazo sin degradación biológica. 4) Podrían modificarse potencialmente con varios tipos de cargas, incluido mRNA, microRNA y proteínas, adaptados al proceso de la enfermedad de interés(2,3). El EXO-CD24 es un producto de investigación biológico basado en exosomas portadores de CD24 que se está investigando como tratamiento de COVID-19. El fundamento de este tratamiento es que los exosomas que sobre expresan CD24, aislados y purificados a partir de células T-REx-293 diseñadas para expresar CD24 en niveles altos, pueden suprimir la tormenta de citocinas, ya que el CD24 ejerce control negativo de la proliferación homeostática de las células T. Este producto es desarrollado por Tel-Aviv Sourasky Medical Center(4). Estudios publicados: No se identificó ningún estudio publicado concerniente a EXO-CD24, al efectuar la búsqueda a través de la Plataforma Living Overview of the Evidence (L·OVE)1 de la Fundación Epistemonikos, con fecha 22 de febrero de 2021. CONCLUSIONES: EXO-CD24 es un producto de investigación biológico, basado en exosomas portadores de CD24, que se está investigando como tratamiento para COVID-19 moderado/severo en un ensayo clínico fase 1 en Israel, cuyo objetivo principal es evaluar su seguridad. No se identificó ninguna publicación científica respecto EXO-CD24. Por consiguiente, los resultados del referido ensayo clínico de fase 1 aún no han sido publicados ni registrados en ClinicalTrials.gov hasta la fecha.

Treatment with soluble CD24 attenuates COVID-19-associated systemic immunopathology.

BACKGROUND: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) through direct lysis of infected lung epithelial cells, which releases damage-associated molecular patterns and induces a pro-inflammatory cytokine milieu causing systemic inflammation. Anti-viral and anti-inflammatory agents have shown limited therapeutic efficacy. Soluble CD24 (CD24Fc) blunts the broad inflammatory response induced by damage-associated molecular patterns via binding to extracellular high mobility group box 1 and heat shock proteins, as well as regulating the downstream Siglec10-Src homology 2 domain-containing phosphatase 1 pathway. A recent randomized phase III trial evaluating CD24Fc for patients with severe COVID-19 (SAC-COVID; NCT04317040) demonstrated encouraging clinical efficacy. METHODS: Using a systems analytical approach, we studied peripheral blood samples obtained from patients enrolled at a single institution in the SAC-COVID trial to discern the impact of CD24Fc treatment on immune homeostasis. We performed high dimensional spectral flow cytometry and measured the levels of a broad array of cytokines and chemokines to discern the impact of CD24Fc treatment on immune homeostasis in patients with COVID-19. RESULTS: Twenty-two patients were enrolled, and the clinical characteristics from the CD24Fc vs. placebo groups were matched. Using high-content spectral flow cytometry and network-level analysis, we found that patients with severe COVID-19 had systemic hyper-activation of multiple cellular compartments, including CD8+ T cells, CD4+ T cells, and CD56+ natural killer cells. Treatment with CD24Fc blunted this systemic inflammation, inducing a return to homeostasis in NK and T cells without compromising the anti-Spike protein antibody response. CD24Fc significantly attenuated the systemic cytokine response and diminished the cytokine coexpression and network connectivity linked with COVID-19 severity and pathogenesis. CONCLUSIONS: Our data demonstrate that CD24Fc rapidly down-modulates systemic inflammation and restores immune homeostasis in SARS-CoV-2-infected individuals, supporting further development of CD24Fc as a novel therapeutic against severe COVID-19.

DNA Aptamers for the Malignant Transformation Marker CD24.

Cluster of differentiation 24 (CD24) is a cell surface glycoprotein, which is largely present on hematopoietic cells and many types of solid tumor cells. CD24 is known to be involved in a wide range of downstream signaling pathways and neural development, yet the underlying mechanisms are poorly understood. Moreover, its production correlates with poor cancer prognosis, and targeting of CD24 with different antibodies has been shown to inhibit disease progression. Nucleic acid aptamers are oligonucleotides that are selected from random DNA or RNA libraries for high affinity and specific binding to a certain target. Thus, they can be used as an alternative to antibodies. To gain an insight on CD24 role and its interaction partners, we performed several SELEX (systematic evolution of ligands by exponential enrichment) experiments to select CD24-specfiic DNA aptamers. We found that the cell-SELEX approach was the most useful and that using HT-29 cell line presenting CD24 along with CD24 knockdown HT-29 cells has selected six aptamers. For the selected aptamers, we determined dissociation constants in the nanomolar range (18-709 nM) using flow cytometry. These aptamers can be applied as diagnostic tools to track cancer progression and bear a potential for therapeutic use for inhibiting signaling pathways that promote the metastatic process.