Clofarabine Has a Superior Therapeutic Window as compared to Gemcitabine in Preclinical Bladder Cancer Models.

Current standard-of-care systemic therapy options for locally advanced and metastatic bladder cancer (BC), which are predominantly based on cisplatin-gemcitabine combinations, are limited by significant treatment failure rates and frailty-based patient ineligibility. We previously addressed the urgent clinical need for better-tolerated BC therapeutic strategies using a drug screening approach, which identified outstanding antineoplastic activity of clofarabine in preclinical models of BC. To further assess clofarabine as a potential BC therapy component, we conducted head-to-head comparisons of responses to clofarabine versus gemcitabine in preclinical in vitro and in vivo models of BC, complemented by in silico analyses.

Kinase-inactivated CDK6 preserves the long-term functionality of adult hematopoietic stem cells.

Hematopoietic stem cells (HSCs) are characterized by the ability to self-renew and to replenish the hematopoietic system. The cell-cycle kinase cyclin-dependent kinase 6 (CDK6) regulates transcription, whereby it has both kinase-dependent and kinase-independent functions. Herein, we describe the complex role of CDK6, balancing quiescence, proliferation, self-renewal, and differentiation in activated HSCs.

Recent contributions of single-cell and spatial profiling to the understanding of bladder cancer.

Purpose Of Review: Current risk stratification and treatment decision-making for bladder cancer informed by histopathology as well as molecular diagnostics face limitations. This review summarizes recent advancements in single-cell and spatial omics methodologies for understanding bladder cancer biology and their potential impact on development of novel therapeutic strategies.

Recent Findings: Single-cell RNA sequencing and spatial omics techniques offer unprecedented insights into various aspects of tumor microenvironment (TME), bladder cancer heterogeneity, cancer stemness, and cellular plasticity.

A lineage-specific STAT5BN642H mouse model to study NK-cell leukemia.

Patients with T- and natural killer (NK)-cell neoplasms frequently have somatic STAT5B gain-of-function mutations. The most frequent STAT5B mutation is STAT5BN642H, which is known to drive murine T-cell leukemia, although its role in NK-cell malignancies is unclear. Introduction of the STAT5BN642H mutation into human NK-cell lines enhances their potential to induce leukemia in mice.

SBNO2 is a critical mediator of STAT3-driven hematological malignancies.

Gain-of-function mutations in the signal transducer and activator of transcription 3 (STAT3) gene are recurrently identified in patients with large granular lymphocytic leukemia (LGLL) and in some cases of natural killer (NK)/T-cell and adult T-cell leukemia/lymphoma. To understand the consequences and molecular mechanisms contributing to disease development and oncogenic transformation, we developed murine hematopoietic stem and progenitor cell models that express mutated STAT3Y640F. These cells show accelerated proliferation and enhanced self-renewal potential.

Triple-negative breast cancer cells rely on kinase-independent functions of CDK8 to evade NK-cell-mediated tumor surveillance.

Triple-negative breast cancer (TNBC) is an aggressive malignant disease that is responsible for approximately 15% of breast cancers. The standard of care relies on surgery and chemotherapy but the prognosis is poor and there is an urgent need for new therapeutic strategies. Recent in silico studies have revealed an inverse correlation between recurrence-free survival and the level of cyclin-dependent kinase 8 (CDK8) in breast cancer patients.

A STAT5B-CD9 axis determines self-renewal in hematopoietic and leukemic stem cells.

The transcription factors signal transducer and activator of transcription 5A (STAT5A) and STAT5B are critical in hematopoiesis and leukemia. They are widely believed to have redundant functions, but we describe a unique role for STAT5B in driving the self-renewal of hematopoietic and leukemic stem cells (HSCs/LSCs). We find STAT5B to be specifically activated in HSCs and LSCs, where it induces many genes associated with quiescence and self-renewal, including the surface marker CD9.

T Cell-Intrinsic CDK6 Is Dispensable for Anti-Viral and Anti-Tumor Responses .

The cyclin-dependent kinase 6 (CDK6) regulates the transition through the G1-phase of the cell cycle, but also acts as a transcriptional regulator. As such CDK6 regulates cell survival or cytokine secretion together with STATs, AP-1 or NF-κB. In the hematopoietic system, CDK6 regulates T cell development and promotes leukemia and lymphoma.

A robust approach for the generation of functional hematopoietic progenitor cell lines to model leukemic transformation.

Studies of molecular mechanisms of hematopoiesis and leukemogenesis are hampered by the unavailability of progenitor cell lines that accurately mimic the situation in vivo. We now report a robust method to generate and maintain LSK (Lin-, Sca-1+, c-Kit+) cells, which closely resemble MPP1 cells. HPCLSKs reconstitute hematopoiesis in lethally irradiated recipient mice over >8 months.

A kinase-independent role for CDK8 in BCR-ABL1 leukemia.

Cyclin-dependent kinases (CDKs) are frequently deregulated in cancer and represent promising drug targets. We provide evidence that CDK8 has a key role in B-ALL. Loss of CDK8 in leukemia mouse models significantly enhances disease latency and prevents disease maintenance.

Twins with different personalities: STAT5B-but not STAT5A-has a key role in BCR/ABL-induced leukemia.

Deregulation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway is found in cancer with STAT5A/B controlling leukemic cell survival and disease progression. As mutations in STAT5B, but not STAT5A, have been frequently described in hematopoietic tumors, we used BCR/ABL as model systems to investigate the contribution of STAT5A or STAT5B for leukemogenesis. The absence of STAT5A decreased cell survival and colony formation.

CDK6 coordinates mutant MPN via NF-κB and apoptotic networks.

Over 80% of patients with myeloproliferative neoplasms (MPNs) harbor the acquired somatic mutation. JAK inhibition is not curative and fails to induce a persistent response in most patients, illustrating the need for the development of novel therapeutic approaches. We describe a critical role for CDK6 in MPN evolution.

STAT5BN642H is a driver mutation for T cell neoplasia.

STAT5B is often mutated in hematopoietic malignancies. The most frequent STAT5B mutation, Asp642His (N642H), has been found in over 90 leukemia and lymphoma patients. Here, we used the Vav1 promoter to generate transgenic mouse models that expressed either human STAT5B or STAT5BN642H in the hematopoietic compartment.

SNEV(Prp19/PSO4) deficiency increases PUVA-induced senescence in mouse skin.

Senescent cells accumulate during ageing in various tissues and contribute to organismal ageing. However, factors that are involved in the induction of senescence in vivo are still not well understood. SNEV(P) (rp19/) (PSO) (4) is a multifaceted protein, known to be involved in DNA damage repair and senescence, albeit only in vitro.

Genetic alterations in glucocorticoid signaling pathway components are associated with adverse prognosis in children with relapsed ETV6/RUNX1-positive acute lymphoblastic leukemia.

The ETV6/RUNX1 gene fusion defines the largest genetic subgroup of childhood ALL with overall rapid treatment response. However, up to 15% of cases relapse. Because an impaired glucocorticoid pathway is implicated in disease recurrence we studied the impact of genetic alterations by SNP array analysis in 31 relapsed cases.

Predicting interactome network perturbations in human cancer: application to gene fusions in acute lymphoblastic leukemia.

Genomic variations such as point mutations and gene fusions are directly or indirectly associated with human diseases. They are recognized as diagnostic, prognostic markers and therapeutic targets. However, predicting the functional effect of these genetic alterations beyond affected genes and their products is challenging because diseased phenotypes are likely dependent of complex molecular interaction networks.

Small sizes and indolent evolutionary dynamics challenge the potential role of P2RY8-CRLF2-harboring clones as main relapse-driving force in childhood ALL.

The P2RY8-CRLF2 fusion defines a particular relapse-prone subset of childhood acute lymphoblastic leukemia (ALL) in Italian Association of Pediatric Hematology and Oncology Berlin-Frankfurt-Münster (AIEOP-BFM) 2000 protocols. To investigate whether and to what extent different clone sizes influence disease and relapse development, we quantified the genomic P2RY8-CRLF2 fusion product and correlated it with the corresponding CRLF2 expression levels in patients enrolled in the BFM-ALL 2000 protocol in Austria. Of 268 cases without recurrent chromosomal translocations and high hyperdiploidy, representing approximately 50% of all cases, 67 (25%) were P2RY8-CRLF2 positive.

CREBBP HAT domain mutations prevail in relapse cases of high hyperdiploid childhood acute lymphoblastic leukemia.

Despite their apparently good prognosis ∼15% of high hyperdiploid (HD) childhood acute lymphoblastic leukemia (ALL) cases relapse. To search for responsible risk factors we determined copy number aberrations as well as copy neutral loss of heterozygosity (LOH) in 13 matched diagnosis and relapse samples and added the data of the only three available cases from the literature. Deletions and copy neutral LOH in 3 and 2 of the 16 cases directed us to the histone-modifying CREB-binding protein (CREBBP) gene, whose functional impairment is implicated in drug resistance.

Silencing of ETV6/RUNX1 abrogates PI3K/AKT/mTOR signaling and impairs reconstitution of leukemia in xenografts.

The ETV6/RUNX1 (E/R) gene fusion is generated by the t(12;21) and found in approximately 25% of childhood B-cell precursor acute lymphoblastic leukemia. In contrast to the overwhelming evidence that E/R is critical for the initiation of leukemia, its relevance for the maintenance of overt disease is less clear. To investigate this issue, we suppressed the endogenous E/R fusion protein with lentivirally transduced short hairpin RNA in the leukemia cell lines REH and AT-2, and found a distinct reduction of proliferation and cell survival.

Distinct and redundant functions of histone deacetylases HDAC1 and HDAC2 in proliferation and tumorigenesis.

Histone deacetylases (HDACs) are negative regulators of gene expression and have been implicated in tumorigenesis and tumor progression. Therefore, HDACs are promising targets for anti-tumor drugs. However, the relevant isoforms of the 18 members encompassing HDAC family have not been identified.

ETV6/RUNX1-positive relapses evolve from an ancestral clone and frequently acquire deletions of genes implicated in glucocorticoid signaling.

Approximately 25% of childhood acute lymphoblastic leukemias carry the ETV6/RUNX1 fusion gene. Despite their excellent initial treatment response, up to 20% of patients relapse. To gain insight into the relapse mechanisms, we analyzed single nucleotide polymorphism arrays for DNA copy number aberrations (CNAs) in 18 matched diagnosis and relapse leukemias.

Conditional deletion of histone deacetylase 1 in T cells leads to enhanced airway inflammation and increased Th2 cytokine production.

Chromatin modifications, such as reversible histone acetylation, play a key role in the regulation of T cell development and function. However, the role of individual histone deacetylases (HDACs) in T cells is less well understood. In this article, we show by conditional gene targeting that T cell-specific loss of HDAC1 led to an increased inflammatory response in an in vivo allergic airway inflammation model.

The cyclin-dependent kinase inhibitor p21 is a crucial target for histone deacetylase 1 as a regulator of cellular proliferation.

Histone deacetylases (HDACs) are chromatin-modifying enzymes that are involved in the regulation of proliferation, differentiation and development. HDAC inhibitors induce cell cycle arrest, differentiation, or apoptosis in tumor cells and are therefore promising antitumor agents. Numerous genes were found to be deregulated upon HDAC inhibitor treatment; however, the relevant target enzymes are still unidentified.