biventricular-assessment-cardiac-function-pressure-volume-loops

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) ...

Queen's University

Recent studies suggest that lung cancer stem cells (CSCs) may play major roles in lung cancer. Therefore, identification of lung CSC drivers may provide promising targets for lung cancer. TAZ is a transcriptional co-activator and key downstream effector of the Hippo pathway, which plays critical roles in various biological processes. TAZ has been shown to be overexpressed in lung cancer and involved in tumorigenicity of lung epithelial cells. However, whether TAZ is a driver for lung CSCs and tumor formation in vivo is unknown. In addition, the molecular mechanism underlying TAZ-induced lung tumorigenesis remains to be determined. In this study, we provided evidence that constitutively active TAZ (TAZ-S89A) is a driver for lung tumorigenesis in vivo in mice and formation of lung CSC. Further RNA-seq and qRT-PCR analysis identified Aldh1a1, a well-established CSC marker, as critical TAZ downstream target and showed that TAZ induces Aldh1a1 transcription by activating its promoter activity through interaction with the transcription factor TEAD. Most significantly, inhibition of ALDH1A1 with its inhibitor A37 or CRISPR gene knockout in lung cancer cells suppressed lung tumorigenic and CSC phenotypes in vitro, and tumor formation in mice in vivo. In conclusion, this study identified TAZ as a novel inducer of lung CSCs and the first transcriptional activator of the stem cell marker ALDH1A1. Most significantly, we identified ALDH1A1 as a critical meditator of TAZ-induced tumorigenic and CSC phenotypes in lung cancer. Our studies provided preclinical data for targeting of TAZ-TEAD-ALDH1A1 signaling to inhibit CSC-induced lung tumorigenesis in the future.

TAZ induces lung cancer stem cell properties and tumorigenesis by up-regulating ALDH1A1.

Tet methylcytosine dioxygenase 2 (TET2) is one of the earliest and most frequently mutated genes in clonal hematopoiesis of indeterminate potential (CHIP) and myeloid cancers, including myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML). TET2 catalyzes the oxidation of 5-methylcytosine to 5-hydroxymethylcytosine, leading to DNA demethylation, and also affects transcription by recruiting histone modifiers. Inactivating TET2 mutations cause epigenetic dysregulation, clonal hematopoietic stem cell (HSC) dominance, and monocytic lineage skewing. Here, we found that Tet2 was the most highly expressed Tet enzyme in murine macrophage (MΦ) differentiation. Tet2 transcription was further induced by lipopolysaccharide (LPS), but not interleukin (IL)-4, stimulation, potentially in a nuclear factor κβ-dependent manner. Tet2 loss did not affect early LPS gene responses in vitro, but increased Il-1b, Il-6, and Arginase 1 (Arg1) mRNA expression at later stages of stimulation in bone-marrow-derived MΦs (BMMΦs). Tet2-deficient peritoneal MΦs, however, demonstrated profound, constitutive expression of LPS-induced genes associated with an inflammatory state in vivo. In contrast, Tet2 deficiency did not affect alternative MΦ gene expression significantly in response to IL-4. These results suggested impaired resolution of inflammation in the absence of Tet2 both in vitro and in vivo. For the first time, we also detected TET2 mutations in BMMΦs from MDS and CMML patients and assayed their effects on LPS responses, including their potential influence on human IL-6 expression. Our results show that Tet2 restrains inflammation in murine MΦs and mice, raising the possibility that loss of TET2 function in MΦs may alter the immune environment in the large elderly population with TET2-mutant CHIP and in TET2-mutant myeloid cancer patients.

Tet2 restrains inflammatory gene expression in macrophages.

The Hippo pathway component WW domain-containing transcription regulator 1 (TAZ) is a transcriptional coactivator and an oncogene in breast and lung cancer. Transcriptional targets of TAZ that modulate immune cell function in the tumor microenvironment are poorly understood. Here, we perform a comprehensive screen for immune-related genes regulated by TAZ and its paralog YAP using NanoString gene expression profiling. We identify the immune checkpoint molecule  as a target of Hippo signaling. The upstream kinases of the Hippo pathway, mammalian STE20-like kinase 1 and 2 (MST1/2), and large tumor suppressor 1 and 2 (LATS1/2), suppress PD-L1 expression while TAZ and YAP enhance PD-L1 levels in breast and lung cancer cell lines. PD-L1 expression in cancer cell lines is determined by TAZ activity and TAZ/YAP/TEAD increase  promoter activity. Critically, TAZ-induced PD-L1 upregulation in human cancer cells is sufficient to inhibit T-cell function. The relationship between TAZ and PD-L1 is not conserved in multiple mouse cell lines, likely due to differences between the human and mouse  promoters. To explore the extent of divergence in TAZ immune-related targets between human and mouse cells, we performed a second NanoString screen using mouse cell lines. We show that many targets of TAZ may be differentially regulated between these species. These findings highlight the role of Hippo signaling in modifying human/murine physiologic/pathologic immune responses and provide evidence implicating TAZ in human cancer immune evasion. Human-specific activation of PD-L1 by a novel Hippo signaling pathway in cancer immune evasion may have a significant impact on research in immunotherapy. .

The Hippo Pathway Component TAZ Promotes Immune Evasion in Human Cancer through PD-L1.

Aging hematopoietic stem cells acquire mutations that sometimes impart a selective advantage. Next-generation DNA sequencing (NGS) can be used to detect expanded peripheral blood progeny of a mutant clone, usually carrying just one cancer-driver mutation, most often in the epigenetic regulator genes, DNMT3A or TET2. This phenomenon is known as clonal hematopoiesis (CH), age-related CH (ARCH) when considering its association with age, and CH of indeterminate potential (CHIP) when the variant allele fraction (VAF) is at least 2% in peripheral leukocytes. CHIP is present in at least 10-15% of adults older than 65 years and is a risk factor for hematological neoplasms and diseases exacerbated by mutant, hyper-inflammatory, monocytes/macrophages, such as atherosclerotic cardiovascular disease. Therefore, the detection of CHIP has important clinical consequences. Herein, we present a protocol for the generation of targeted, amplicon-based, NGS libraries for ion semiconductor sequencing and CHIP detection, using Ion Torrent platforms.

Targeted, Amplicon-Based, Next-Generation Sequencing to Detect Age-Related Clonal Hematopoiesis.

The mechanisms by which patients with RUNX1 familial platelet disorder with propensity to myeloid malignancies (FPDMM) develop myeloid malignancies (MM) are not fully understood. We report the results of targeted next-generation sequencing on three patients with RUNX1 FPDMM who developed acute myeloid leukaemia or myelodysplastic syndromes (AML/MDS). DNA samples were collected from bone marrow, peripheral blood and buccal swabs at different time points. One patient had clonal haematopoiesis, represented by an SRSF2 p.P95R variant, prior to his AML diagnosis, when he developed an additional NRAS p.G12D variant. His sister presented to us with MDS, with a TET2 p.S471fs and identical NRAS p.G12D variant. The third patient, from another family, had an additional RUNX1 p.R204X and an NFE2 p.Q139fs variant at AML diagnosis. This constitutes the first report of NFE2 variants in AML without extramedullary disease and NRAS variants in AML/MDS in the setting of FPDMM. A systematic review of the literature including our findings distinguishes two genetic landscapes at AML transformation from FPDMM characterized by either the presence or absence of somatic abnormalities in RUNX1 with or without variants in genes usually associated with MM. Whether clonal haematopoiesis precedes transformation only in patients without somatic abnormalities in RUNX1 needs further confirmation.

Longitudinal sequencing of RUNX1 familial platelet disorder: new insights into genetic mechanisms of transformation to myeloid malignancies.

Comorbid and inflammatory characteristics of genetic subtypes of clonal hematopoiesis.

 Pulmonary arterial hypertension (PAH) is a lethal vasculopathy. Hereditary cases are associated with germline mutations in  and 16 other genes. However, these mutations occur in under 25% of idiopathic PAH patients (IPAH) and are rare in PAH associated with connective tissue diseases (APAH). Preclinical studies suggest epigenetic dysregulation, including altered DNA methylation, promotes PAH. Somatic mutations of Tet-methylcytosine-dioxygenase-2 (), a key enzyme in DNA demethylation, occur in cardiovascular disease and are associated with clonal hematopoiesis, inflammation and adverse vascular remodeling. The role of  in PAH is unknown.  To test for a role of , we utilized a cohort of 2572 cases from the PAH Biobank. Within this cohort, gene-specific rare variant association tests were performed using 1832 unrelated European PAH patients and 7509 non-Finnish European gnomAD subjects as controls. In an independent cohort of 140 patients, we quantified  expression in peripheral blood mononuclear cells. To assess causality, we investigated hemodynamic and histologic evidence of PAH in hematopoietic -knockout mice.  We observed an increased burden of rare, predicted deleterious, germline variants in  in PAH patients of European ancestry (9/1832) compared to controls (6/7509; relative risk=6, p=0.00067). Assessing the whole cohort, 0.39% (10/2572) of patients had 12  mutations (75% predicted germline and 25% somatic). These patients had no mutations in other PAH-related genes. Patients with  mutations were older (71±7 years versus 48±19 years, p<0.0001) unresponsive to vasodilator challenge (0/7 vs 140/1055 (13.2%)), had lower PVR (5.2±3.1 versus 10.5±7.0 Woods units, p=0.02) and had increased inflammation (including elevation of IL-1β). Circulating  expression did not correlate with age and was decreased in >86% of PAH patients. -knockout mice spontaneously developed PAH, adverse pulmonary vascular remodeling and inflammation, with elevated levels of cytokines, including IL-1β. Chronic therapy with an antibody targeting IL-1β blockade regressed PAH.  PAH is the first human disease related to potential  germline mutations. Inherited and acquired abnormalities of  occur in 0.39% of PAH cases. Decreased  expression is ubiquitous and has potential as a PAH biomarker.

Brooke Snetsinger

Department of Medicine

Queen's University

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Brooke Snetsinger

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Medicine

Queen's University

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Department of Medicine