Biology subjects

Koldobskiy, M. A.

Publications and source records attributed to Koldobskiy, M. A..

4 recordsLinked to original sources

bioRxiv2026

Combination epigenetic-targeted therapy increases the immunogenicity of poorly immunogenic sarcomas

Immunotherapy approaches have shown limited efficacy in pediatric sarcomas, partly because these tumors have low mutation burden and few neoantigens. We sought to increase the immunogenicity of low mutation sarcomas by inducing expression of epigenetically silenced genes using the hypomethylating agent decitabine and histone deacetylase inhibitor entinostat. Using a mutated Kras-driven murine sarcoma model KP Sarc, sequential treatment with decitabine and entinostat significantly increased expression of silenced genes, including cancer testis antigens, and enhanced antigen presentation, including MHC I expression, compared with either agent alone. Vaccination with irradiated, epigenetically treated KP Sarc cells in a GM-CSF-secreting whole-cell vaccine induced T cell immunity against a matched tumor challenge. The anti-tumor response was directed toward epigenetically upregulated antigens, was T cell dependent, was further potentiated by immune checkpoint inhibition, and conferred immunologic memory. We showed that epigenetically regulated antigens can be shared between tumors providing protective immunity against both epigenetically treated KP Sarc and a second murine sarcoma M-3-9M. Treatment of human sarcoma lines with decitabine and entinostat induced similar gene expression changes, including shared antigen targets, and increased MHC I expression. These findings demonstrate that epigenetically upregulated antigens can serve as effective tumor-specific targets and broaden immunotherapy strategies for low-mutation sarcomas.

immunology↗

bioRxiv2024

DNMT3AR882H Is Not Required for Disease Maintenance in Primary Human AML, but Is Associated With Increased Leukemia Stem Cell Frequency

Genetic mutations are being thoroughly mapped in human cancers, yet a fundamental question in cancer biology is whether such mutations are functionally required for cancer initiation, maintenance of established cancer, or both. Here, we study this question in the context of human acute myeloid leukemia (AML), where DNMT3AR882 missense mutations often arise early, in pre-leukemic clonal hematopoiesis, and corrupt the DNA methylation landscape to initiate leukemia. We developed CRISPR-based methods to directly correct DNMT3AR882 mutations in leukemic cells obtained from patients. Surprisingly, DNMT3AR882 mutations were largely dispensable for disease maintenance. Replacing DNMT3AR882 mutants with wild-type DNMT3A did not impair the ability of AML cells to engraft in vivo, and minimally altered DNA methylation. Taken together, DNMT3AR882 mutations are initially necessary for AML initiation, but are largely dispensable for disease maintenance. The notion that initiating oncogenes differ from those that maintain cancer has important implications for cancer evolution and therapy. STATEMENT OF SIGNIFICANCEUnderstanding which driver mutations are required for cancer initiation, maintenance, or both phases remains poorly understood. Here, we uncover that highly prevalent pre-leukemic DNMT3A mutations are only required during disease initiation, but become dispensable after leukemic transformation, uncovering the context-specific role of this driver mutation with important therapeutic implications.

cancer biology↗

bioRxiv2023

Convergence of aging- and rejuvenation-related epigenetic alterations on PRC2 targets

Rejuvenation of tissues in physiologically aging mice can be accomplished by long-term partial reprogramming via expression of reprogramming factors (Oct4, Sox2, Klf4 and c-Myc). To investigate the epigenetic determinants of partial reprogramming-mediated rejuvenation, we used whole genome bisulfite sequencing to carry out unbiased comprehensive profiling of DNA methylation changes in skin from mice subjected to partial reprogramming, as well as young and untreated old controls. We found a striking convergence of age- and rejuvenation-related epigenetic alterations on targets of the Polycomb repressive complex 2 (PRC2). These results are also supported by a likewise prominent enrichment of PRC2 targets in gene expression data, suggesting that PRC2 activity can modulate aging and mediate tissue rejuvenation.

genomics↗

bioRxiv2021

Engineering CAR-NK cells to secrete IL15 sustains their anti-AML functionality, but is associated with systemic toxicities

BackgroundThe prognosis of patients with recurrent/refractory acute myelogenous leukemia (AML) remains poor and cell-based immunotherapies hold promise to improve outcomes. NK cells can elicit an anti-leukemic response via a repertoire of activating receptors that bind AML surface ligands. NK cell adoptive transfer is safe but thus far has shown limited anti-AML efficacy. Here, we aimed to overcome this limitation by engineering NK cells to express chimeric antigen receptors (CARs) to boost their anti-AML activity, and interleukin-15 (IL15) to enhance their persistence. MethodsWe characterized in detail NK cell populations expressing a panel of AML (CD123)-specific CARs and/or IL15 in vitro and in AML xenograft models. ResultsCARs with 2B4.{zeta} or 4-1BB.{zeta} signaling domains demonstrated greater cell surface expression and endowed NK cells with improved anti-AML activity in vitro. Initial in vivo testing revealed that only 2B4.{zeta} CAR-NK cells had improved anti-AML activity in comparison to untransduced (UTD) and 4-1BB.{zeta} CAR-NK cells. However, the benefit was transient due to limited CAR-NK cell persistence. Transgenic expression of secretory (s)IL15 in 2B4.{zeta} CAR and UTD NK cells improved their effector function in the setting of chronic antigen simulation in vitro. Multiparameter flow analysis after chronic antigen exposure identified the expansion of unique NK cell subsets. 2B4.{zeta}/sIL15 CAR and sIL15 NK cells maintained an overall activated NK cell phenotype. This was confirmed by transcriptomic analysis, which revealed a highly proliferative and activated signature in these NK cell groups. In vivo, 2B4.{zeta}/sIL15 CAR-NK cells had potent anti-AML activity in one model, while 2B4.{zeta}/sIL15 CAR and sIL15 NK cells induced lethal toxicity in a second model. ConclusionTransgenic expression of CD123-CARs and sIL15 enabled NK cells to function in the setting of chronic antigen exposure but was associated with systemic toxicities. Thus, our study provides the impetus to explore inducible and controllable expression systems to provide cytokine signals to AML-specific CAR-NK cells before embarking on early phase clinical testing. O_FIG O_LINKSMALLFIG WIDTH=161 HEIGHT=200 SRC="FIGDIR/small/461509v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@4d09eaorg.highwire.dtl.DTLVardef@1c61411org.highwire.dtl.DTLVardef@14f8097org.highwire.dtl.DTLVardef@8375ac_HPS_FORMAT_FIGEXP M_FIG C_FIG In BriefSecretion of IL15 from anti-CD123.2B4.CD3{zeta} CAR-NK cells enhances their activation and killing potential against Acute Myelogenous Leukemia, but carries the risk of severe systemic toxicity.

immunology↗