Biology subjects

Kulozik, A. E.

Publications and source records attributed to Kulozik, A. E..

3 recordsLinked to original sources

bioRxiv2024

Role of Stem-Like Cells in Chemotherapy Resistance and Relapse in pediatric T Cell Acute Lymphoblastic Leukemia

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia predominantly affecting adolescents and young adults. T-ALL relapses are characterized by chemotherapy resistance, cellular heterogeneity and dismal outcome. To gain a deeper understanding of the cellular heterogeneity and mechanisms driving relapse, we conducted single-cell full-length RNA sequencing of 13 matched pediatric T-ALL patient-derived xenografts (PDX) samples obtained at initial diagnosis and relapse, generating the to date most comprehensive longitudinal single cell study in paired T-ALL samples, along with 5 non-relapsing PDX samples collected at initial diagnosis. This dataset identifies considerable transcriptomic diversity among individual T-ALL cell populations. Notably however, 11 of the 18 patients exhibit a small T-ALL cell subpopulation with a shared set of gene regulatory networks characterized by a common set of active regulons, expression patterns and splice isoforms. This profile involves the upregulation of a stem-like cell signature with enrichment of cell adhesion, and inhibition of the cell cycle and metabolic activity. Comprehensive investigations of these networks identify transcripts enforcing drug resistance through NF-{kappa}B expression and TGF-{beta} signaling and of anti-apoptotic T cell signaling. Longitudinal monitoring of these stem-like cells demonstrates this subpopulation to account for only a small proportion of leukemia cells initially with a substantial expansion at relapse suggesting resistance to first line therapy. Chemotherapy resistance is functionally corroborated through in vitro and in vivo drug testing. We thus report the discovery of inherently treatment-resistant stem-like T-ALL cell populations underscoring the potential for devising future therapeutic strategies aimed at targeting stemness pathways in pediatric T-ALL. Key PointsO_LISingle-cell full-length RNA sequencing reveals dormant, treatment-resistant cells expanding upon T cell acute lymphoblastic leukemia relapse. C_LIO_LIStem-like T-ALL cells exhibit a shared gene regulatory network conferring chemotherapy resistance and relapse. C_LI

cancer biology↗

bioRxiv2021

Haplotype-aware single-cell multiomics uncovers functional effects of somatic structural variation

Somatic structural variants (SVs) are widespread in cancer genomes, however, their impact on tumorigenesis and intra-tumour heterogeneity is incompletely understood, since methods to functionally characterize the broad spectrum of SVs arising in cancerous single-cells are lacking. We present a computational method, scNOVA, that couples SV discovery with nucleosome occupancy analysis by haplotype-resolved single-cell sequencing, to systematically uncover SV effects on cis-regulatory elements and gene activity. Application to leukemias and cell lines uncovered SV outcomes at several loci, including dysregulated cancer-related pathways and mono-allelic oncogene expression near SV breakpoints. At the intra-patient level, we identified different yet overlapping subclonal SVs that converge on aberrant Wnt signaling. We also deconvoluted the effects of catastrophic chromosomal rearrangements resulting in oncogenic transcription factor dysregulation. scNOVA directly links SVs to their functional consequences, opening the door for single-cell multiomics of SVs in heterogeneous cell populations.

genomics↗

bioRxiv2020

Pharmacological inhibition of nonsense-mediated RNA decay augments HLA class I-mediated presentation of neoepitopes in MSI CRC

Microsatellite-unstable (MSI) colorectal cancer is characterized by the accumulation of somatic insertion/deletion (InDel) mutations potentially generating tumor-specific, frameshifted protein sequences. Such mutations typically generate premature translation termination codons targeting the affected mRNAs to degradation by nonsense-mediated RNA decay (NMD), limiting the synthesis and HLA class I-mediated presentation of tumor-specific InDel neoepitopes. We reasoned that the NMD inhibitor 5-azacytidine (5AZA) could serve to increase the expression of NMD-sensitive neoepitopes and analyzed the immunopeptidome of MSI HCT-116 cells using a proteogenomic approach. After immunoprecipitation of HLA:peptide complexes, we identified more than 10,000 HLA class I-presented peptides by LC-MS/MS including five InDel neoepitopes. The InDel neoepitopes were verified on the genomic, transcriptomic, and peptidomic level. Treatment with 5AZA increased the expression of the corresponding frameshift- and premature termination codon-bearing mRNAs and enhanced the presentation of peptides originating from known NMD targets and one of the identified InDel neoepitopes. By analyzing an array of MSI colorectal cancer cell lines and patient samples, we found the underlying frameshift mutation to be highly recurrent and immunization with the corresponding neoepitope induced strong CD8+ T cell responses in an HLA-A*02:01 transgenic mouse model. Our data directly show that peptides originating from frameshifted open reading frames due to InDel mutations in mismatch repair-deficient cells are presented on the cell surface via HLA class I. Moreover, we demonstrate the utility of NMD inhibitor-enhanced HLA class I-mediated presentation of InDel neoepitopes as well as their immunogenicity, uncovering the clinical potential of NMD inhibition in anti-cancer immunotherapy strategies. One Sentence SummaryImmunopeptidomics identified increased HLA class I-mediated presentation of immunogenic, frameshift-derived neoepitopes following NMD inhibition.

cancer biology↗