ORCID Profile
0000-0001-9262-7529
Current Organisation
University of Veterinary Medicine Vienna
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Publisher: EMBO
Date: 07-11-2022
Abstract: Leukemic cutaneous T‐cell lymphomas (L‐CTCL) are lymphoproliferative disorders of skin‐homing mature T‐cells causing severe symptoms and high mortality through chronic inflammation, tissue destruction, and serious infections. Despite numerous genomic sequencing efforts, recurrent driver mutations have not been identified, but chromosomal losses and gains are frequent and dominant. We integrated genomic landscape analyses with innovative pharmacologic interference studies to identify key vulnerable nodes in L‐CTCL. We detected copy number gains of loci containing the STAT3/5 oncogenes in 74% ( n = 17/23) of L‐CTCL, which correlated with the increased clonal T‐cell count in the blood. Dual inhibition of STAT3/5 using small‐molecule degraders and multi‐kinase blockers abolished L‐CTCL cell growth in vitro and ex vivo , whereby PAK kinase inhibition was specifically selective for L‐CTCL patient cells carrying STAT3/5 gains. Importantly, the PAK inhibitor FRAx597 demonstrated encouraging anti‐leukemic activity in vivo by inhibiting tumor growth and disease dissemination in intradermally xenografted mice. We conclude that STAT3/5 and PAK kinase interaction represents a new therapeutic node to be further explored in L‐CTCL.
Publisher: Springer Science and Business Media LLC
Date: 07-06-2019
DOI: 10.1038/S41467-019-10422-7
Abstract: Hyper-activated STAT5B variants are high value oncology targets for pharmacologic intervention. STAT5B N642H , a frequently-occurring oncogenic driver mutation, promotes aggressive T-cell leukemia/lymphoma in patient carriers, although the molecular origins remain unclear. Herein, we emphasize the aggressive nature of STAT5B N642H in driving T-cell neoplasia upon hematopoietic expression in transgenic mice, revealing evidence of multiple T-cell subset organ infiltration. Notably, we demonstrate STAT5B N642H -driven transformation of γδ T-cells in in vivo syngeneic transplant models, comparable to STAT5B N642H patient γδ T-cell entities. Importantly, we present human STAT5B and STAT5B N642H crystal structures, which propose alternative mutation-mediated SH2 domain conformations. Our biophysical data suggests STAT5B N642H can adopt a hyper-activated and hyper-inactivated state with resistance to dephosphorylation. MD simulations support sustained interchain cross-domain interactions in STAT5B N642H , conferring kinetic stability to the mutant anti-parallel dimer. This study provides a molecular explanation for the STAT5B N642H activating potential, and insights into pre-clinical models for targeted intervention of hyper-activated STAT5B.
Publisher: Informa UK Limited
Date: 24-11-2017
Publisher: Ferrata Storti Foundation (Haematologica)
Date: 30-09-2019
Publisher: MDPI AG
Date: 27-02-2019
DOI: 10.3390/IJMS20051028
Abstract: O-GlcNAcylation is a post-translational modification that influences tyrosine phosphorylation in healthy and malignant cells. O-GlcNAc is a product of the hexosamine biosynthetic pathway, a side pathway of glucose metabolism. It is essential for cell survival and proper gene regulation, mirroring the metabolic status of a cell. STAT3 and STAT5 proteins are essential transcription factors that can act in a mutational context-dependent manner as oncogenes or tumor suppressors. They regulate gene expression for vital processes such as cell differentiation, survival, or growth, and are also critically involved in metabolic control. The role of STAT3/5 proteins in metabolic processes is partly independent of their transcriptional regulatory role, but is still poorly understood. Interestingly, STAT3 and STAT5 are modified by O-GlcNAc in response to the metabolic status of the cell. Here, we discuss and summarize evidence of O-GlcNAcylation-regulating STAT function, focusing in particular on hyperactive STAT5A transplant studies in the hematopoietic system. We emphasize that a single O-GlcNAc modification is essential to promote development of neoplastic cell growth through enhancing STAT5A tyrosine phosphorylation. Inhibition of O-GlcNAcylation of STAT5A on threonine 92 lowers tyrosine phosphorylation of oncogenic STAT5A and ablates malignant transformation. We conclude on strategies for new therapeutic options to block O-GlcNAcylation in combination with tyrosine kinase inhibitors to target neoplastic cancer cell growth and survival.
Publisher: MDPI AG
Date: 03-12-2019
Abstract: Signal transducer and activator of transcription (STAT)3 and STAT5 are important transcription factors that are able to mediate or even drive cancer progression through hyperactivation or gain-of-function mutations. Mutated STAT3 is mainly associated with large granular lymphocytic T-cell leukemia, whereas mutated STAT5B is associated with T-cell prolymphocytic leukemia, T-cell acute lymphoblastic leukemia and γδ T-cell-derived lymphomas. Hyperactive STAT3 and STAT5 are also implicated in various hematopoietic and solid malignancies, such as chronic and acute myeloid leukemia, melanoma or prostate cancer. Classical understanding of STAT functions is linked to their phosphorylated parallel dimer conformation, in which they induce gene transcription. However, the functions of STAT proteins are not limited to their phosphorylated dimerization form. In this review, we discuss the functions and the roles of unphosphorylated STAT3/5 in the context of chromatin remodeling, as well as the impact of STAT5 oligomerization on differential gene expression in hematopoietic neoplasms. The central involvement of STAT3/5 in cancer has made these molecules attractive targets for small-molecule drug development, but currently there are no direct STAT3/5 inhibitors of clinical grade available. We summarize the development of inhibitors against the SH2 domains of STAT3/5 and discuss their applicability as cancer therapeutics.
Publisher: MDPI AG
Date: 08-11-2019
Abstract: Src Homology 2 (SH2) domains arose within metazoan signaling pathways and are involved in protein regulation of multiple pleiotropic cascades. In signal transducer and activator of transcription (STAT) proteins, SH2 domain interactions are critical for molecular activation and nuclear accumulation of phosphorylated STAT dimers to drive transcription. Sequencing analysis of patient s les has revealed the SH2 domain as a hotspot in the mutational landscape of STAT proteins although the functional impact for the vast majority of these mutations remains poorly characterized. Despite several well resolved structures for SH2 domain-containing proteins, structural data regarding the distinctive STAT-type SH2 domain is limited. Here, we review the unique features of STAT-type SH2 domains in the context of all currently reported STAT3 and STAT5 SH2 domain clinical mutations. The genetic volatility of specific regions in the SH2 domain can result in either activating or deactivating mutations at the same site in the domain, underscoring the delicate evolutionary balance of wild type STAT structural motifs in maintaining precise levels of cellular activity. Understanding the molecular and biophysical impact of these disease-associated mutations can uncover convergent mechanisms of action for mutations localized within the STAT SH2 domain to facilitate the development of targeted therapeutic interventions.
No related grants have been discovered for Anna Orlova.