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Sapozhnikova, V.

Publications and source records attributed to Sapozhnikova, V..

2 recordsLinked to original sources

Targetable BIRC5 dependency in therapy-resistant TP53 mutated acute myeloid leukemia

TP53 mutations across multiple cancers, including acute myeloid leukemia (AML), are associated with poor outcomes irrespective of treatment modality. However, druggable vulnerabilities beyond canonical p53 targets remain largely unexplored. We identify BIRC5 (encodes survivin), an inhibitor of the apoptosis protein (IAP) family, as a novel vulnerability in TP53 mutant AML using an unbiased, comprehensive multiomics approach -- whole-genome CRISPR knockout screen, bulk and single-cell RNA-seq, proteomics, and high-throughput drug screen. Mechanistically, BIRC5 deletion in AML restored caspase-9 and -3/7 activity and downregulated other IAPs, implicating BIRC5 as the central post-mitochondrial regulator for blocking apoptosis. p53 stabilization suppressed BIRC5 selectively in TP53 wild-type AML, explaining BIRC5 upregulation in TP53 mutant lines and AML primary tumors (n > 700). Longitudinal single-cell RNAseq (n = 22 pairs) revealed expansion of BIRC5high stem and progenitor leukemia clones in TP53 mutant AML patients post-VenAza therapy. Survivin and IAP inhibitors emerged as top combination partners with VenAza in TP53 mutant AML cells and showed potent in vivo leukemic blast inhibition in cell line and patient-derived xenograft models along with primary tumors. Beyond AML, BIRC5 was upregulated broadly across 17 of 25 TP53 mutant cancers in the TCGA cohort, and combination with survivin inhibitors overcame chemotherapy resistance in TP53 deficient triple negative breast and colorectal cancers. These findings define BIRC5 as a critical, targetable dependency and unveil survivin/IAP inhibition as a promising therapeutic axis to overcome p53-related resistance across both hematologic and solid malignancies. Key PointsO_LIBIRC5 upregulation is a novel dependency in TP53 mutant AML that mediates therapy resistance by evasion of apoptosis. C_LIO_LICombination with Survivin/IAP inhibitors overcomes venetoclax/azacitidine resistance in TP53 mutant AML. C_LI

cancer biology↗

A comprehensive motifs-based interactome of the C/EBPα transcription factor

The pioneering transcription factor C/EBP coordinates cell fate and cell differentiation. C/EBP represents an intrinsically disordered protein with multiple short linear motifs and extensive post-translational side chain modifications (PTM), reflecting its modularity and functional plasticity. Here, we combined arrayed peptide matrix screening (PRISMA) with biotin ligase proximity labeling proteomics (BioID) to generate a linear, isoform specific and PTM-dependent protein interaction map of C/EBP in myeloid cells. The C/EBP interactome comprises promiscuous and PTM-regulated interactions with protein machineries involved in gene expression, epigenetics, genome organization, DNA replication, RNA processing, and nuclear transport as the basis of functional C/EBP plasticity. Protein interaction hotspots were identified that coincide with homologous conserved regions of the C/EBP family and revealed interaction motifs that score as molecular recognition features (MoRF). PTMs alter the interaction spectrum of multi-valent C/EBP-motifs to configure a multimodal transcription factor hub that allows interaction with multiple co-regulatory components, including BAF/SWI-SNF or Mediator complexes. Combining PRISMA and BioID acts as a powerful strategy to systematically explore the interactomes of intrinsically disordered proteins and their PTM-regulated, multimodal capacity. Key pointsO_LIIntegration of proximity labeling and arrayed peptide screen proteomics refines the interactome of C/EBP isoforms C_LIO_LIHotspots of protein interactions in C/EBP mostly occur in conserved short linear motifs C_LIO_LIInteractions of the BAF/SWI-SNF complex with C/EBP are modulated by arginine methylation and isoform status C_LIO_LIThe integrated experimental strategy suits systematic interactome studies of intrinsically disordered proteins C_LI

molecular biology↗