{"id":{"repo_id":"milano","oai_identifier":"oai:air.unimi.it:2434/1198291"},"canonical_url":"https://search.dev.ndltd.org/etd/milano/oai:air.unimi.it:2434/1198291","repository":{"repo_id":"milano","name":"Università degli Studi di Milano","base_url":"https://air.unimi.it/oai/request"},"display":{"title":"EXPLORING THE PRE-LEUKEMIC PHASE OF ACUTE PROMYELOCYTIC LEUKEMIA: INSIGHTS FROM STUDIES OF SINGLE CELL ¿OMICS¿","abstract":"Acute Promyelocytic Leukemia (APL) is a distinct subtype of Acute Myeloid Leukemia (AML) driven by the oncogenic fusion protein PML-RAR, which acts as an aberrant transcription factor and blocks myeloid maturation at the promyelocyte stage. In vivo, the expression of PML-RAR is necessary but not sufficient for full-blown leukemia: knock-in (KI) mouse models of APL undergo a prolonged pre-leukemic phase during which hematopoiesis appears normal. This stage provides a unique opportunity to investigate the earliest molecular and cellular alterations that precede the disease. To dissect early events, a transgenic PML-RAR model was used in combination with high-resolution single-cell technologies. Hematopoietic stem cells (HSCs), common myeloid progenitors (CMPs), and a residual and more differentiated lineage-negative Sca-1-c-Kit- (LSK-) subpopulation were profiled via bulk RNA-seq, single-cell RNA-seq (scRNA-Seq), and single-cell ATAC-seq (scATAC-Seq). The integrated analysis revealed that PML-RAR expression maintains largely unaltered the overall transcriptional program of pre-leukemic cells, while driving cell cycle and a selective expansion of specific cell subtypes, correlated with a reduction of chromatin accessibility at several genomic loci. Functional assays corroborated these findings. Transplantation experiments demonstrated that PML-RAR-expressing cells from the three hematopoietic compartments gave rise to transplantable leukemia, albeit with different efficiency. Of note, following lethal irradiation, these cells provide radioprotection and long-term repopulation in recipient mice, indicating that PML-RAR confers an advantage that becomes particularly evident in perturbed conditions. Comparison with published datasets further reinforced our observations. A transcriptional signature directly regulated by PML-RAR expression identified in human NB4 APL cells was detected in our analysis of single-cell data. Notably, the signature was confined to the expanded subpopulations, despite differences in species and experimental context. This supports the idea that expanded pre-leukemic progenitors represent the origin of transformation. Together, these results indicate that PML-RAR is able to initiate leukemogenesis through a dual program of chromatin repression and cell cycle dysregulation, selectively expanding progenitor subsets with leukemogenic potential. By integrating transcriptomic, epigenomic and functional data, this work provides a comprehensive map of the earliest oncogenic events of APL, highlighting candidate cell populations from which leukemia may rise. Also, these findings advance the understanding of pre-leukemic biology and suggest novel therapeutic strategies which may intercept disease at its earliest stages.","abstract_html":"Acute Promyelocytic Leukemia (APL) is a distinct subtype of Acute Myeloid Leukemia (AML) driven by the oncogenic fusion protein PML-RAR, which acts as an aberrant transcription factor and blocks myeloid maturation at the promyelocyte stage. In vivo, the expression of PML-RAR is necessary but not sufficient for full-blown leukemia: knock-in (KI) mouse models of APL undergo a prolonged pre-leukemic phase during which hematopoiesis appears normal. This stage provides a unique opportunity to investigate the earliest molecular and cellular alterations that precede the disease. To dissect early events, a transgenic PML-RAR model was used in combination with high-resolution single-cell technologies. Hematopoietic stem cells (HSCs), common myeloid progenitors (CMPs), and a residual and more differentiated lineage-negative Sca-1-c-Kit- (LSK-) subpopulation were profiled via bulk RNA-seq, single-cell RNA-seq (scRNA-Seq), and single-cell ATAC-seq (scATAC-Seq). The integrated analysis revealed that PML-RAR expression maintains largely unaltered the overall transcriptional program of pre-leukemic cells, while driving cell cycle and a selective expansion of specific cell subtypes, correlated with a reduction of chromatin accessibility at several genomic loci. Functional assays corroborated these findings. Transplantation experiments demonstrated that PML-RAR-expressing cells from the three hematopoietic compartments gave rise to transplantable leukemia, albeit with different efficiency. Of note, following lethal irradiation, these cells provide radioprotection and long-term repopulation in recipient mice, indicating that PML-RAR confers an advantage that becomes particularly evident in perturbed conditions. Comparison with published datasets further reinforced our observations. A transcriptional signature directly regulated by PML-RAR expression identified in human NB4 APL cells was detected in our analysis of single-cell data. Notably, the signature was confined to the expanded subpopulations, despite differences in species and experimental context. This supports the idea that expanded pre-leukemic progenitors represent the origin of transformation. Together, these results indicate that PML-RAR is able to initiate leukemogenesis through a dual program of chromatin repression and cell cycle dysregulation, selectively expanding progenitor subsets with leukemogenic potential. By integrating transcriptomic, epigenomic and functional data, this work provides a comprehensive map of the earliest oncogenic events of APL, highlighting candidate cell populations from which leukemia may rise. Also, these findings advance the understanding of pre-leukemic biology and suggest novel therapeutic strategies which may intercept disease at its earliest stages.","abstract_has_math":false,"creators":["VILLA, EMANUELA"],"institution":"Università degli Studi di Milano","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["tutor: S. Minucci ; phd coordinator: D. Pasini","E. Villa","MINUCCI, SAVERIO","PASINI, DIEGO"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-12-17","date_published":"2025-12-17","updated_at":"2026-07-27T20:18:56Z","subjects":["single-cell RNA-seq","single-cell ATAC-seq","PML-RARa","pre-leukemia","Settore MEDS-02/A - Patologia generale"],"languages":["eng"],"rights":["info:eu-repo/semantics/embargoedAccess","license:Creative commons","license uri:http://creativecommons.org/licenses/by-sa/4.0/"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2434/1198291","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["tutor: S. Minucci ; phd coordinator: D. Pasini","E. 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In vivo, the expression of PML-RAR is necessary but not sufficient for full-blown leukemia: knock-in (KI) mouse models of APL undergo a prolonged pre-leukemic phase during which hematopoiesis appears normal. This stage provides a unique opportunity to investigate the earliest molecular and cellular alterations that precede the disease. To dissect early events, a transgenic PML-RAR model was used in combination with high-resolution single-cell technologies. Hematopoietic stem cells (HSCs), common myeloid progenitors (CMPs), and a residual and more differentiated lineage-negative Sca-1-c-Kit- (LSK-) subpopulation were profiled via bulk RNA-seq, single-cell RNA-seq (scRNA-Seq), and single-cell ATAC-seq (scATAC-Seq). The integrated analysis revealed that PML-RAR expression maintains largely unaltered the overall transcriptional program of pre-leukemic cells, while driving cell cycle and a selective expansion of specific cell subtypes, correlated with a reduction of chromatin accessibility at several genomic loci. Functional assays corroborated these findings. Transplantation experiments demonstrated that PML-RAR-expressing cells from the three hematopoietic compartments gave rise to transplantable leukemia, albeit with different efficiency. Of note, following lethal irradiation, these cells provide radioprotection and long-term repopulation in recipient mice, indicating that PML-RAR confers an advantage that becomes particularly evident in perturbed conditions. Comparison with published datasets further reinforced our observations. A transcriptional signature directly regulated by PML-RAR expression identified in human NB4 APL cells was detected in our analysis of single-cell data. Notably, the signature was confined to the expanded subpopulations, despite differences in species and experimental context. This supports the idea that expanded pre-leukemic progenitors represent the origin of transformation. Together, these results indicate that PML-RAR is able to initiate leukemogenesis through a dual program of chromatin repression and cell cycle dysregulation, selectively expanding progenitor subsets with leukemogenic potential. By integrating transcriptomic, epigenomic and functional data, this work provides a comprehensive map of the earliest oncogenic events of APL, highlighting candidate cell populations from which leukemia may rise. Also, these findings advance the understanding of pre-leukemic biology and suggest novel therapeutic strategies which may intercept disease at its earliest stages."]},{"key":"dc:title","label":"Title","values":["EXPLORING THE PRE-LEUKEMIC PHASE OF ACUTE PROMYELOCYTIC LEUKEMIA: INSIGHTS FROM STUDIES OF SINGLE CELL ¿OMICS¿"]}]}],"canonical_facts":{"dc:contributor":["tutor: S. Minucci ; phd coordinator: D. Pasini","E. Villa","MINUCCI, SAVERIO","PASINI, DIEGO"],"dc:creator":["VILLA, EMANUELA"],"dc:date":["2025-12-17"],"dc:description":["Acute Promyelocytic Leukemia (APL) is a distinct subtype of Acute Myeloid Leukemia (AML) driven by the oncogenic fusion protein PML-RAR, which acts as an aberrant transcription factor and blocks myeloid maturation at the promyelocyte stage. In vivo, the expression of PML-RAR is necessary but not sufficient for full-blown leukemia: knock-in (KI) mouse models of APL undergo a prolonged pre-leukemic phase during which hematopoiesis appears normal. This stage provides a unique opportunity to investigate the earliest molecular and cellular alterations that precede the disease. To dissect early events, a transgenic PML-RAR model was used in combination with high-resolution single-cell technologies. Hematopoietic stem cells (HSCs), common myeloid progenitors (CMPs), and a residual and more differentiated lineage-negative Sca-1-c-Kit- (LSK-) subpopulation were profiled via bulk RNA-seq, single-cell RNA-seq (scRNA-Seq), and single-cell ATAC-seq (scATAC-Seq). The integrated analysis revealed that PML-RAR expression maintains largely unaltered the overall transcriptional program of pre-leukemic cells, while driving cell cycle and a selective expansion of specific cell subtypes, correlated with a reduction of chromatin accessibility at several genomic loci. Functional assays corroborated these findings. Transplantation experiments demonstrated that PML-RAR-expressing cells from the three hematopoietic compartments gave rise to transplantable leukemia, albeit with different efficiency. Of note, following lethal irradiation, these cells provide radioprotection and long-term repopulation in recipient mice, indicating that PML-RAR confers an advantage that becomes particularly evident in perturbed conditions. Comparison with published datasets further reinforced our observations. A transcriptional signature directly regulated by PML-RAR expression identified in human NB4 APL cells was detected in our analysis of single-cell data. Notably, the signature was confined to the expanded subpopulations, despite differences in species and experimental context. This supports the idea that expanded pre-leukemic progenitors represent the origin of transformation. Together, these results indicate that PML-RAR is able to initiate leukemogenesis through a dual program of chromatin repression and cell cycle dysregulation, selectively expanding progenitor subsets with leukemogenic potential. By integrating transcriptomic, epigenomic and functional data, this work provides a comprehensive map of the earliest oncogenic events of APL, highlighting candidate cell populations from which leukemia may rise. Also, these findings advance the understanding of pre-leukemic biology and suggest novel therapeutic strategies which may intercept disease at its earliest stages."],"dc:identifier":["https://hdl.handle.net/2434/1198291"],"dc:language":["eng"],"dc:publisher":["Università degli Studi di Milano"],"dc:relation":["numberofpages:155"],"dc:rights":["info:eu-repo/semantics/embargoedAccess","license:Creative commons","license uri:http://creativecommons.org/licenses/by-sa/4.0/"],"dc:subject":["single-cell RNA-seq","single-cell ATAC-seq","PML-RARa","pre-leukemia","Settore MEDS-02/A - Patologia generale"],"dc:title":["EXPLORING THE PRE-LEUKEMIC PHASE OF ACUTE PROMYELOCYTIC LEUKEMIA: INSIGHTS FROM STUDIES OF SINGLE CELL ¿OMICS¿"],"dc:type":["info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-27T20:18:56Z"}