Periodic Reporting for period 4 - PML-THERAPY (HARNESSING PML NUCLEAR BODIES FOR LEUKAEMIA THERAPY)
Periodo di rendicontazione: 2023-10-01 al 2024-06-30
Apart from surgery, cancers are currently treated with very diverse approaches (chemotherapy, hormonal therapy, targeted therapies, radiotherapies, immunotherapies) How exactly these therapies yield clinical benefit in patients has been a matter of some controversies. Basic science is thus essential to understand the molecular and cellular bases for therapy response, notably to optimize drug combinations. In a specific form of AML, acute promyelocytic leukaemia (APL), we previously unravelled (with ERC support) the molecular basis for response to arsenic therapy, demonstrating that the PML protein plays a key role. Physiologically, PML behaves as an oxidative stress sensor and contributes to redox homeostasis. PML organizes nuclear bodies (NBs), domains that recruit multiple client proteins to facilitate their post-translational modifications (PTM), particularly conjugation of SUMOs. This controls multiple downstream pathways such as P53, but also cell cycle progression or interferon signalling (IFN). In APL, NB-disruption blunts P53-driven senescence, contributing to oncogenesis and therapy resistance. Therapy-induced NB-restoration is required for efficient APL clearance. More broadly, PML expression and/or NB-formation are lost upon many viral infections or during cancer development.
We are interested in the mechanistic basis of therapy response of acute myeloid leukaemia (AML). In the context of the current ERC grant, we want to explore the possibility that PML may play a role in AML responses to other therapies. Unravelling novel molecular mechanisms associated with therapy response will foster novel therapeutic approaches, notably drug combinations, that have immediate societal impact. Our aim is to mechanistically dissect PML signalling in vivo and therapeutically restore it in malignancies where it is inactivated. We first propose a broad exploration of PML in mice to identify basal and stress-induced PML PTM and identify the repertoire of proteins sumoylated in a PML- dependent manner. We will generate a series of PML knock-in mutant mice and analyse their P53-regulated redox homeostasis. We will mechanistically explore PML-driven senescence in leukaemia models where we have evidence for basal or therapy-responsive NB-modulation: acute myeloid leukaemia expressing NPMc or IFN-sensitive JAK2-driven leukaemia. We will screen chemical libraries for drugs modulating PML expression and/or NB biogenesis. Finally, we will integrate our findings to elaborate innovative therapeutic strategies based on restoration of the PML/P53 checkpoint in leukaemia with unmet medical needs.
Over the course of the complete grant, we have provided unambiguous evidence that PML indeed plays a key role in therapeutic response in multiple forms of acute leukaemia. In particular, in JAK2-driven myeloproliferative neoplasms, we demonstrated that the know therapeutic effects of IFN are boosted by arsenic, in a PML-dependent manner. Similarly, in NPM1c-driven AMLs, we found that Actinomycin D, an approved anti-cancer drug, has clinical activity through induction of ROS that target PML. Mechanistically, we identified the arsenic-binding site of PML, a solvent-exposed cysteine residue that appears to be the ROS-sensing site. Finally, we demonstrated that conventional AML chemotherapy requires PML presence for a full efficacy. Fine structure-function analyses have been performed and point to specific molecular mechanisms.
Overall, our work has positioned PML as a central hub of stress response, notably for the response to cancer therapies. PML is already targetable by arsenic, but newer PML-targeting agents may be discovered in the future. More broadly, our studies bring novel vision to the molecular and cellular mechanisms contributing to the clinical activity of conventional AML chemotherapies.
We are interested in the mechanistic basis of therapy response of acute myeloid leukaemia (AML). In the context of the current ERC grant, we want to explore the possibility that PML may play a role in AML responses to other therapies. Unravelling novel molecular mechanisms associated with therapy response will foster novel therapeutic approaches, notably drug combinations, that have immediate societal impact. Our aim is to mechanistically dissect PML signalling in vivo and therapeutically restore it in malignancies where it is inactivated. We first propose a broad exploration of PML in mice to identify basal and stress-induced PML PTM and identify the repertoire of proteins sumoylated in a PML- dependent manner. We will generate a series of PML knock-in mutant mice and analyse their P53-regulated redox homeostasis. We will mechanistically explore PML-driven senescence in leukaemia models where we have evidence for basal or therapy-responsive NB-modulation: acute myeloid leukaemia expressing NPMc or IFN-sensitive JAK2-driven leukaemia. We will screen chemical libraries for drugs modulating PML expression and/or NB biogenesis. Finally, we will integrate our findings to elaborate innovative therapeutic strategies based on restoration of the PML/P53 checkpoint in leukaemia with unmet medical needs.
Over the course of the complete grant, we have provided unambiguous evidence that PML indeed plays a key role in therapeutic response in multiple forms of acute leukaemia. In particular, in JAK2-driven myeloproliferative neoplasms, we demonstrated that the know therapeutic effects of IFN are boosted by arsenic, in a PML-dependent manner. Similarly, in NPM1c-driven AMLs, we found that Actinomycin D, an approved anti-cancer drug, has clinical activity through induction of ROS that target PML. Mechanistically, we identified the arsenic-binding site of PML, a solvent-exposed cysteine residue that appears to be the ROS-sensing site. Finally, we demonstrated that conventional AML chemotherapy requires PML presence for a full efficacy. Fine structure-function analyses have been performed and point to specific molecular mechanisms.
Overall, our work has positioned PML as a central hub of stress response, notably for the response to cancer therapies. PML is already targetable by arsenic, but newer PML-targeting agents may be discovered in the future. More broadly, our studies bring novel vision to the molecular and cellular mechanisms contributing to the clinical activity of conventional AML chemotherapies.
We provided evidence that PML plays a key role in therapeutic response in several forms of acute leukaemia, with different forms of therapies. For example, in JAK2-driven myeloproliferative neoplasms, the therapeutic effects of IFN are boosted by arsenic, in a PML-dependent manner, while in NPM1c-driven AMLs, Actinomycin D has clinical activity through induction of ROS and targeting of PML.
Mechanistically, we identified the arsenic-binding site of PML, a solvent-exposed cysteine residue that appears to be the ROS-sensing site, highjacked by arsenic during APL therapy. Finally, we demonstrated that conventional AML chemotherapy requires PML presence for a full efficacy. A set of knock-in alleles of PML targeting critical residues of its functional domains were obtained in mice. These were used to generate a set of AML models, so as to decipher the roles of specific PML domains in therapy response. A comprehensive structure/function analysis was performed and raises some interesting new insights into the determinants of the clinical activities of conventional chemotherapies. Mechanistically, they provide an unexpected parallel with APL therapy, stressing the importance of PML in pathogenesis and therapy response of very different types of AMLs.
Addressing the molecular mechanisms through which PML may influence the response to anticancer drugs, we established the role of PML in controlling stress-induced SUMO2 conjugation, which is followed by proteasome mediated degradation. Proteomic studies have identified a number of novel SUMO protein targets regulated by PML and oxidative stress. These could be key effectors of senescence.
Overall, the studies performed in the last 6 years have shed a new light on the roles of PML in modulating therapeutic sensitivity of leukaemia in vivo. They also provided insights into the control of sumoylation by oxidative stress. These findings were reported in a number of well-attended scientific conferences, as well as some communication dedicated to the lay public. These two published studies have significant clinical impact, as they provide a basis for therapeutic trials assessing the efficacy of ActD+Venetoclax associations in NPM1c-AML patients. They also make a strong case for combined IFN/ATO trials in MPN.
Mechanistically, we identified the arsenic-binding site of PML, a solvent-exposed cysteine residue that appears to be the ROS-sensing site, highjacked by arsenic during APL therapy. Finally, we demonstrated that conventional AML chemotherapy requires PML presence for a full efficacy. A set of knock-in alleles of PML targeting critical residues of its functional domains were obtained in mice. These were used to generate a set of AML models, so as to decipher the roles of specific PML domains in therapy response. A comprehensive structure/function analysis was performed and raises some interesting new insights into the determinants of the clinical activities of conventional chemotherapies. Mechanistically, they provide an unexpected parallel with APL therapy, stressing the importance of PML in pathogenesis and therapy response of very different types of AMLs.
Addressing the molecular mechanisms through which PML may influence the response to anticancer drugs, we established the role of PML in controlling stress-induced SUMO2 conjugation, which is followed by proteasome mediated degradation. Proteomic studies have identified a number of novel SUMO protein targets regulated by PML and oxidative stress. These could be key effectors of senescence.
Overall, the studies performed in the last 6 years have shed a new light on the roles of PML in modulating therapeutic sensitivity of leukaemia in vivo. They also provided insights into the control of sumoylation by oxidative stress. These findings were reported in a number of well-attended scientific conferences, as well as some communication dedicated to the lay public. These two published studies have significant clinical impact, as they provide a basis for therapeutic trials assessing the efficacy of ActD+Venetoclax associations in NPM1c-AML patients. They also make a strong case for combined IFN/ATO trials in MPN.
At the current stage of the project, our studies imply a much broader role for PML in therapy response than anticipated. This justifies the emphasis put on PML biology, as it may yield novel therapeutic approaches. Our studies have immediate therapeutic impact and discussions are ongoing with clinical groups to implement the new concepts drawn from our work into innovative clinical trials. They also raise novel hypotheses as to the role of oxidative stress in conventional chemotherapy.