Clinical Pathology - Research Publications
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ItemEpigenetic Changes in Diabetes and Cardiovascular Risk(LIPPINCOTT WILLIAMS & WILKINS, 2016-05-27)Cardiovascular complications remain the leading causes of morbidity and premature mortality in patients with diabetes mellitus. Studies in humans and preclinical models demonstrate lasting gene expression changes in the vasculopathies initiated by previous exposure to high glucose concentrations and the associated overproduction of reactive oxygen species. The molecular signatures of chromatin architectures that sensitize the genome to these and other cardiometabolic risk factors of the diabetic milieu are increasingly implicated in the biological memory underlying cardiovascular complications and now widely considered as promising therapeutic targets. Atherosclerosis is a complex heterocellular disease where the contributing cell types possess distinct epigenomes shaping diverse gene expression. Although the extent that pathological chromatin changes can be manipulated in human cardiovascular disease remains to be established, the clinical applicability of epigenetic interventions will be greatly advanced by a deeper understanding of the cell type-specific roles played by writers, erasers, and readers of chromatin modifications in the diabetic vasculature. This review details a current perspective of epigenetic mechanisms of macrovascular disease in diabetes mellitus and highlights recent key descriptions of chromatinized changes associated with persistent gene expression in endothelial, smooth muscle, and circulating immune cells relevant to atherosclerosis. Furthermore, we discuss the challenges associated with pharmacological targeting of epigenetic networks to correct abnormal or deregulated gene expression as a strategy to alleviate the clinical burden of diabetic cardiovascular disease.
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ItemPI3K Activation in Neural Stem Cells Drives Tumorigenesis which can be Ameliorated by Targeting the cAMP Response Element Binding (CREB) Protein(Oxford University Press, 2018-10)BACKGROUND: Hyperactivation of phosphoinositide 3-kinase (PI3K) signaling is common in cancers, but the precise role of the pathway in glioma biology remains to be determined. Some understanding of PI3K signaling mechanisms in brain cancer comes from studies on neural stem/progenitor cells (NSPCs), where signals transmitted via the PI3K pathway cooperate with other intracellular pathways and downstream transcription factors to regulate critical cell functions. METHODS: To investigate the role of the PI3K pathway in glioma initiation and development, we generated a mouse model targeting the inducible expression of a PIK3CAH1047A oncogenic mutant and deletion of the PI3K negative regulator, phosphatase and tensin homolog (PTEN), to NSPCs. RESULTS: Expression of a Pik3caH1047A was sufficient to generate tumors with oligodendroglial features, but simultaneous loss of PTEN was required for the development of invasive, high-grade glioma. Pik3caH1047A-PTEN mutant NSPCs exhibited enhanced neurosphere formation which correlated with increased Wnt signaling, while loss of cAMP response element binding protein (CREB) in Pik3caH1047A-Pten mutant tumors led to longer symptom-free survival in mice. CONCLUSION: Taken together, our findings present a novel mouse model for glioma demonstrating that the PI3K pathway is important for initiation of tumorigenesis and that disruption of downstream CREB signaling attenuates tumor expansion.
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ItemNo Preview AvailableA MXI1-NUTM1 fusion protein with MYC-like activity suggests a novel oncogenic mechanism in a subset ofNUTM1-rearranged tumors(ELSEVIER SCIENCE INC, 2021-01)Most NUTM1-rearranged neoplasms (NRNs) have fusions between NUTM1 and BRD (bromodomain-containing) family members and are termed NUT carcinomas (NCs) because they show some squamous differentiation. However, some NRNs are associated with fusions between NUTM1 and members of the MAD (MAX dimerization) gene family of MYC antagonists. Here we describe a small round cell malignancy from the gastro-esophageal junction with a previously unreported fusion between NUTM1 and the MAD family member MXI1. In contrast to NCs, the MXI1-NUTM1 tumor did not show squamous differentiation and did not express MYC, TP63 or SOX2, genes known to be targets of BRD-NUTM1 proteins and critical for NC oncogenesis. Transcriptome analysis showed paradoxical enrichment of MYC target genes in the MXI1-NUTM1 tumor despite the lack of MYC expression. When expressed in vitro MXI1-NUTM1 partially phenocopied MYC, enhancing cell proliferation and cooperating with oncogenic HRAS to produce anchorage-independent cell growth. These data provide evidence that MAD family members, which are normally repressors of MYC activity, can be converted into MYC-like mimics by fusion to NUTM1. The pathological features and novel oncogenic mechanism of the MXI1-NUTM1 tumor show that identification of NUTM1 fusion partners can be important for accurate diagnostic classification of some NRN subtypes, and potentially may guide therapeutic options.
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ItemUltrasound-Stimulated Microbubbles Enhance Radiation-Induced Cell Killing(Elsevier, 2022-12)Recent in vivo studies using ultrasound-stimulated microbubbles as a localized radiosensitizer have had impressive results. While in vitro studies have also obtained similar results using human umbilical vein endothelial cells (HUVEC), studies using other cell lines have had varying results. This study was aimed at investigating any increases in radiation-induced cell killing in vitro using two carcinoma lines not previously investigated before (metastatic follicular thyroid carcinoma cells [FTC-238] and non-small cell lung carcinoma cells [NCI-H727]), in addition to HUVEC. Cells were treated using a combination of 1.6% (v/v) microbubbles, ∼90 s of 2-MHz ultrasound (mechanical index = 0.8) and 0–6 Gy of kilovolt or MV X-rays. Cell viability assays obtained 72 h post-treatment were normalized to untreated controls, and analysis of variance was used to determine statistical significance. All cells treated with combined ultrasound-stimulated microbubbles and radiation exhibited decreased normalized survival, with statistically significant effects observed for the NCI-H727 cells. No statistically significant differences in effects were observed using kV compared with MV radiation. Further studies using increased microbubble concentrations may be required to achieve statistically significant results for the FTC-238 and HUVEC lines.
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ItemNo Preview AvailablePresenilin 1 interacts with acetylcholinesterase and alters its enzymatic activity and glycosylation(AMER SOC MICROBIOLOGY, 2008-05)Presenilin 1 (PS1) plays a critical role in the gamma-secretase processing of the amyloid precursor protein to generate the beta-amyloid peptide, which accumulates in plaques in the pathogenesis of Alzheimer's disease (AD). Mutations in PS1 cause early onset AD, and proteins that interact with PS1 are of major functional importance. We report here the coimmunoprecipitation of PS1 and acetylcholinesterase (AChE), an enzyme associated with amyloid plaques. Binding occurs through PS1 N-terminal fragment independent of the peripheral binding site of AChE. Subcellular colocalization of PS1 and AChE in cultured cells and coexpression patterns of PS1 and AChE in brain sections from controls and subjects with sporadic or familial AD indicated that PS1 and AChE are located in the same intracellular compartments, including the perinuclear compartments. A PS1-A246E pathogenic mutation expressed in transgenic mice leads to decreased AChE activity and alteration of AChE glycosylation and the peripheral binding site, which may reflect a shift in protein conformation and disturbed AChE maturation. In both the transgenic mice and humans, mutant PS1 impairs coimmunoprecipitation with AChE. The results indicate that PS1 can interact with AChE and influence its expression, supporting the notion of cholinergic-amyloid interrelationships.
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ItemNo Preview AvailableVascular endothelial growth factor d is dispensable for development of the lymphatic system(AMER SOC MICROBIOLOGY, 2005-03)Vascular endothelial growth factor receptor 3 (Vegfr-3) is a tyrosine kinase that is expressed on the lymphatic endothelium and that signals for the growth of the lymphatic vessels (lymphangiogenesis). Vegf-d, a secreted glycoprotein, is one of two known activating ligands for Vegfr-3, the other being Vegf-c. Vegf-d stimulates lymphangiogenesis in tissues and tumors; however, its role in embryonic development was previously unknown. Here we report the generation and analysis of mutant mice deficient for Vegf-d. Vegf-d-deficient mice were healthy and fertile, had normal body mass, and displayed no pathologic changes consistent with a defect in lymphatic function. The lungs, sites of strong Vegf-d gene expression during embryogenesis in wild-type mice, were normal in Vegf-d-deficient mice with respect to tissue mass and morphology, except that the abundance of the lymphatics adjacent to bronchioles was slightly reduced. Dye uptake experiments indicated that large lymphatics under the skin were present in normal locations and were functional. Smaller dermal lymphatics were similar in number, location, and function to those in wild-type controls. The lack of a profound lymphatic phenotype in Vegf-d-deficient mice suggests that Vegf-d does not play a major role in lymphatic development or that Vegf-c or another, as-yet-unknown activating Vegfr-3 ligand can compensate for Vegf-d during development.
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ItemDiagnosis, management and follow up of peripheral T-cell lymphomas: a consensus practice statement from the Australasian Lymphoma Alliance(WILEY, 2022-10)Peripheral T-cell lymphomas (PTCL) represent a heterogeneous disease group accounting for 10% of non-Hodgkin lymphomas. PTCL patients have typically poorer outcomes compared with aggressive B-cell lymphomas. However, such outcomes are heavily dependent on subtype. Although anthracycline-based regimens such as cyclophosphamide, doxorubicin, vincristine and prednisone remain the standard first-line treatment for most aggressive PTCL, there are important variations including incorporation of novel agents, use of radiotherapy and judicious consideration of stem cell transplantation. Relapsed or refractory disease represents a significant area of unmet need where chemotherapy intensification has limited efficacy and novel agents such as brentuximab vedotin and pralatrexate provide additional opportunities for attainment of remission and potential stem cell transplant. In the future, pre-therapy prognostic biomarkers including genomic characterisation, may aid in risk stratification and help guide initial patient management to improve survival. There is an urgent need to understand better the pathogenesis of PTCL to facilitate novel drug combinatorial approaches to improve survival. This position statement represents an evidence-based synthesis of the literature for application in Australian and New Zealand practice.
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ItemDevelopment and initial validation of a deep learning algorithm to quantify histological features in colorectal carcinoma including tumour budding/poorly differentiated clusters(WILEY, 2021-09)AIMS: To develop and validate a deep learning algorithm to quantify a broad spectrum of histological features in colorectal carcinoma. METHODS AND RESULTS: A deep learning algorithm was trained on haematoxylin and eosin-stained slides from tissue microarrays of colorectal carcinomas (N = 230) to segment colorectal carcinoma digitised images into 13 regions and one object. The segmentation algorithm demonstrated moderate to almost perfect agreement with interpretations by gastrointestinal pathologists, and was applied to an independent test cohort of digitised whole slides of colorectal carcinoma (N = 136). The algorithm correctly classified mucinous and high-grade tumours, and identified significant differences between mismatch repair-proficient and mismatch repair-deficient (MMRD) tumours with regard to mucin, inflammatory stroma, and tumour-infiltrating lymphocytes (TILs). A cutoff of >44.4 TILs per mm2 carcinoma gave a sensitivity of 88% and a specificity of 73% in classifying MMRD carcinomas. Algorithm measures of tumour budding (TB) and poorly differentiated clusters (PDCs) outperformed TB grade derived from routine sign-out, and compared favourably with manual counts of TB/PDCs with regard to lymphatic, venous and perineural invasion. Comparable associations were seen between algorithm measures of TB/PDCs and manual counts of TB/PDCs for lymph node metastasis (all P < 0.001); however, stronger correlations were seen between the proportion of positive lymph nodes and algorithm measures of TB/PDCs. Stronger associations were also seen between distant metastasis and algorithm measures of TB/PDCs (P = 0.004) than between distant metastasis and TB (P = 0.04) and TB/PDC counts (P = 0.06). CONCLUSIONS: Our results highlight the potential of deep learning to identify and quantify a broad spectrum of histological features in colorectal carcinoma.
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ItemNo Preview AvailablePlasmodium Falciparum: Cytoadherence occurring in the absence of knobs uses the thrombospondin receptor (CD36)(Elsevier BV, 1990)P. falciparum is the cause of the lethal form of malaria which results in thousands of deaths each year. The primary cause of death, cerebral malaria, is associated with the sequestration of erythrocytes infected with the mature stages of P. falciparum (trophozoites and schizonts) in the post capillary venules of the brain. The identification of the parasite protein(s) involved in this process will provide important vaccine candidate molecules and knowledge about the pathological processes involved in cell-cell adhesion in general. The mechanism of cytoadherence is studied in vitro using cultured lines of P. falciparum which bind to umbilical vein endothelial cells and C32 amelanotic melanoma cells. Mature stages of the parasite may induce knob-like protrusions in the erythrocyte membrane, and it was previously thought that ‘knobs’ were necessary although not sufficient for cytoadherence to occur both in vitro and during natural infection. We have derived a clone of the Brazilian isolate of P. falciparum, ITG2F6, and selected for cytoadherence by repeated passage over amelanotic melanoma cells. Chromosome analysis using pulsed-field gradient electrophoresis and DNA amplification using the polymerase chain reaction reveal that this clone has deleted the gene coding for knobs. Furthermore, cytoadherence which is independent of knobs occurs via the receptor for the platelet protein, thrombospondin.
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ItemNo Preview AvailablePlasmodium falciparum: Cytoadherence of a knobless clone(Elsevier, 1989-07)Sequestration of Plasmodium falciparum-infected erythrocytes is crucial to parasite survival as it prevents destruction in the liver and spleen. Knobs have been considered necessary but not sufficient for cytoadherence to vascular endothelial cells in vivo and to melanoma or umbilical vein endothelial cells in vitro. We describe here a knobless clone that cytoadheres strongly to C32 melanoma cells. This clone cannot express the knob-associated histidine-rich protein (KAHRP) due to the deletion of the KAHRP gene. Our results raise the possibility of an alternative mechanism for in vitro cytoadherence and suggest that the use of long term cultured isolates and melanoma cells as a model for cytoadherence in vivo may be misleading.