Modelling hereditary diffuse gastric cancer initiation using transgenic mouse-derived gastric organoids and single-cell sequencing.

Hereditary diffuse gastric cancer (HDGC) is a cancer syndrome caused by germline variants in CDH1, the gene encoding the cell-cell adhesion molecule E-cadherin. Loss of E-cadherin in cancer is associated with cellular dedifferentiation and poor prognosis, but the mechanisms through which CDH1 loss initiates HDGC are not known. Using single-cell RNA sequencing, we explored the transcriptional landscape of a murine organoid model of HDGC to characterize the impact of CDH1 loss in early tumourigenesis. Progenitor populations of stratified squamous and simple columnar epithelium, characteristic of the mouse stomach, showed lineage-specific transcriptional programs. Cdh1 inactivation resulted in shifts along the squamous differentiation trajectory associated with aberrant expression of genes central to gastrointestinal epithelial differentiation. Cytokeratin 7 (CK7), encoded by the differentiation-dependent gene Krt7, was a specific marker for early neoplastic lesions in CDH1 carriers. Our findings suggest that deregulation of developmental transcriptional programs may precede malignancy in HDGC. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Hereditary diffuse gastric cancer: updated clinical practice guidelines.

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome that is characterised by a high prevalence of diffuse gastric cancer and lobular breast cancer. It is largely caused by inactivating germline mutations in the tumour suppressor gene CDH1, although pathogenic variants in CTNNA1 occur in a minority of families with HDGC. In this Policy Review, we present updated clinical practice guidelines for HDGC from the International Gastric Cancer Linkage Consortium (IGCLC), which recognise the emerging evidence of variability in gastric cancer risk between families with HDGC, the growing capability of endoscopic and histological surveillance in HDGC, and increased experience of managing long-term sequelae of total gastrectomy in young patients. To redress the balance between the accessibility, cost, and acceptance of genetic testing and the increased identification of pathogenic variant carriers, the HDGC genetic testing criteria have been relaxed, mainly through less restrictive age limits. Prophylactic total gastrectomy remains the recommended option for gastric cancer risk management in pathogenic CDH1 variant carriers. However, there is increasing confidence from the IGCLC that endoscopic surveillance in expert centres can be safely offered to patients who wish to postpone surgery, or to those whose risk of developing gastric cancer is not well defined.

E-cadherin-deficient cells have synthetic lethal vulnerabilities in plasma membrane organisation, dynamics and function.

BACKGROUND: The E-cadherin gene (CDH1) is frequently mutated in diffuse gastric cancer and lobular breast cancer, and germline mutations predispose to the cancer syndrome Hereditary Diffuse Gastric Cancer. We are taking a synthetic lethal approach to identify druggable vulnerabilities in CDH1-mutant cancers. METHODS: Density distributions of cell viability data from a genome-wide RNAi screen of isogenic MCF10A and MCF10A-CDH1-/- cells were used to identify protein classes affected by CDH1 mutation. The synthetic lethal relationship between selected protein classes and E-cadherin was characterised by drug sensitivity assays in both the isogenic breast MCF10A cells and CDH1-isogenic gastric NCI-N87. Endocytosis efficiency was quantified using cholera toxin B uptake. Pathway metagene expression of 415 TCGA gastric tumours was statistically correlated with CDH1 expression. RESULTS: MCF10A-CDH1-/- cells showed significantly altered sensitivity to RNAi inhibition of groups of genes including the PI3K/AKT pathway, GPCRs, ion channels, proteosomal subunit proteins and ubiquitinylation enzymes. Both MCF10A-CDH1-/- and NCI-N87-CDH1-/- cells were more sensitive than wild-type cells to compounds that disrupted plasma membrane composition and trafficking, but showed contrasting sensitivities to inhibitors of actin polymerisation and the chloride channel inhibitor NS3728. The MCF10A-CDH1-/- cell lines showed reduced capacity to endocytose cholera toxin B. Pathway metagene analysis identified 20 Reactome pathways that were potentially synthetic lethal in tumours. Genes involved in GPCR signalling, vesicle transport and the metabolism of PI3K and membrane lipids were strongly represented amongst the candidate synthetic lethal genes. CONCLUSIONS: E-cadherin loss leads to disturbances in receptor signalling and plasma membrane trafficking and organisation, creating druggable vulnerabilities.

E-cadherin loss alters cytoskeletal organization and adhesion in non-malignant breast cells but is insufficient to induce an epithelial-mesenchymal transition.

BACKGROUND: E-cadherin is an adherens junction protein that forms homophilic intercellular contacts in epithelial cells while also interacting with the intracellular cytoskeletal networks. It has roles including establishment and maintenance of cell polarity, differentiation, migration and signalling in cell proliferation pathways. Its downregulation is commonly observed in epithelial tumours and is a hallmark of the epithelial to mesenchymal transition (EMT). METHODS: To improve our understanding of how E-cadherin loss contributes to tumorigenicity, we investigated the impact of its elimination from the non-tumorigenic breast cell line MCF10A. We performed cell-based assays and whole genome RNAseq to characterize an isogenic MCF10A cell line that is devoid of CDH1 expression due to an engineered homozygous 4 bp deletion in CDH1 exon 11. RESULTS: The E-cadherin-deficient line, MCF10A CDH1-/- showed subtle morphological changes, weaker cell-substrate adhesion, delayed migration, but retained cell-cell contact, contact growth inhibition and anchorage-dependent growth. Within the cytoskeleton, the apical microtubule network in the CDH1-deficient cells lacked the radial pattern of organization present in the MCF10A cells and F-actin formed thicker, more numerous stress fibres in the basal part of the cell. Whole genome RNAseq identified compensatory changes in the genes involved in cell-cell adhesion while genes involved in cell-substrate adhesion, notably ITGA1, COL8A1, COL4A2 and COL12A1, were significantly downregulated. Key EMT markers including CDH2, FN1, VIM and VTN were not upregulated although increased expression of proteolytic matrix metalloprotease and kallikrein genes was observed. CONCLUSIONS: Overall, our results demonstrated that E-cadherin loss alone was insufficient to induce an EMT or enhance transforming potential in the non-tumorigenic MCF10A cells but was associated with broad transcriptional changes associated with tissue remodelling.

The relationship between migraine pain and other associated symptoms.

This study explores the relationship of the pain of the migraine headache and the associated features of migraine. Migraineurs (n=1025) (ICHD-2, 1.1-1.2 and 1.5.1) were evaluated retrospectively using a detailed database (daily unremitting excluded). Variables studied included headache intensity and duration, associated symptoms and pain characteristics. Non-parametric correlations were used to evaluate relationships among variables. Headache intensity correlated with nausea, vomiting, photophobia, phonophobia, dizziness (all P=0.000), running of the nose/tearing of the eyes (P=0.007), and osmophobia (P=0.044), but not with diarrhoea or taste abnormality. Headache duration correlated only with osmophobia (P=0.002) and taste abnormality (P=0.005). Throbbing, pressure and stabbing pain correlated with most of the associated symptoms. Aching correlated only with taste abnormality. This correlational study demonstrates that migraine pain is clearly related to nausea, but is also correlated with other associated migraine symptoms. Taste abnormality and osmophobia are better correlated with headache duration rather than headache intensity.

Bacterial tracheitis with upper airway obstruction in a patient with the acquired immunodeficiency syndrome.

Bacterial tracheitis after an upper viral respiratory infection is a well-recognized entity in the pediatric literature. Bacterial tracheitis has only recently been reported in adults, and it is a potentially life-threatening illness. We report a case of bacterial tracheitis in a patient with AIDS.

Some cardiovascular effects of noise.

We recently reported that exposure to moderately high noise levels for 9 months produced sustained blood pressure elevations in rhesus monkeys (M. mulatta) without impairing their auditory sensitivity (Peterson et al, Science, 1981, 211, 143Off). In the present study, a continuation and elaboration of the earlier work, 4 chair-restrained monkeys (M. fascicularis) were studied concurrently. After 3 mo of low-noise conditions, 2 experimental Ss were exposed to a realistic noise sequence [Leq24: 85 db(A)], 24 hrs per day for about 6 mo. Compared to control animals who remained under low-noise conditions throughout the experiment, the noise-exposed Ss again exhibited a substantial increase in blood pressure, and also manifested orderly changes in the diurnal rhythm of heart rate, blood pressure, and "pauses" in cardiac rhythm. Our results conflict in detail with certain findings from earlier epidemiological studies, possibly because of differences in the species used, experimental design, or sampling strategies. The desirability of undertaking long-term prospective studies in this area is discussed.

Computer applications to electrophysiologic studies.

The automated studies performed at implant require little extra time and provide essential information for postoperative troubleshooting and patient management. The automated testing and analysis system is but one component in a comprehensive patient management system designed for and dedicated to pacing; the system is an integral part of a complete data management system which includes extensive follow-up and management sections.

Noise raises blood pressure without impairing auditory sensitivity.

Two rhesus monkeys, exposed continuously to realistic patterns and levels of noise for 9 months, exhibited sustained elevations in blood pressure that did not return to baseline values after the noise ended. Auditory brainstem responses, measured before and after exposure, indicated no change in auditory sensitivity.