Homeostasis, injury, and recovery dynamics at multiple scales in a self-organizing mouse intestinal crypt.

The maintenance of the functional integrity of the intestinal epithelium requires a tight coordination between cell production, migration, and shedding along the crypt-villus axis. Dysregulation of these processes may result in loss of the intestinal barrier and disease. With the aim of generating a more complete and integrated understanding of how the epithelium maintains homeostasis and recovers after injury, we have built a multi-scale agent-based model (ABM) of the mouse intestinal epithelium. We demonstrate that stable, self-organizing behaviour in the crypt emerges from the dynamic interaction of multiple signalling pathways, such as Wnt, Notch, BMP, ZNRF3/RNF43, and YAP-Hippo pathways, which regulate proliferation and differentiation, respond to environmental mechanical cues, form feedback mechanisms, and modulate the dynamics of the cell cycle protein network. The model recapitulates the crypt phenotype reported after persistent stem cell ablation and after the inhibition of the CDK1 cycle protein. Moreover, we simulated 5-fluorouracil (5-FU)-induced toxicity at multiple scales starting from DNA and RNA damage, which disrupts the cell cycle, cell signalling, proliferation, differentiation, and migration and leads to loss of barrier integrity. During recovery, our in silico crypt regenerates its structure in a self-organizing, dynamic fashion driven by dedifferentiation and enhanced by negative feedback loops. Thus, the model enables the simulation of xenobiotic-, in particular chemotherapy-, induced mechanisms of intestinal toxicity and epithelial recovery. Overall, we present a systems model able to simulate the disruption of molecular events and its impact across multiple levels of epithelial organization and demonstrate its application to epithelial research and drug development.

Galectin-3 promotes secretion of proteases that decrease epithelium integrity in human colon cancer cells.

Galectin-3 is a galactoside-binding protein that is commonly overexpressed in many epithelial cancers. It is increasingly recognized as a multi-functional, multi-mode promoter in cancer development, progression, and metastasis. This study reports that galectin-3 secretion by human colon cancer cells induces cancer cell secretion, in an autocrine/paracrine manner, of a number of proteases including cathepsin-B, MMP-1 and MMP-13. The secretion of these proteases causes disruption of epithelial monolayer integrity, increases its permeability and promotes tumour cell invasion. This effect of galectin-3 is shown to be mediated through induction of cellular PYK2-GSK3α/ß signalling and can be prevented by the presence of galectin-3 binding inhibitors. This study thus reveals an important mechanism in galectin-3-mediated promotion of cancer progression and metastasis. It provides further evidence to the increased realization of galectin-3 as a potential therapeutic target for the treatment of cancer.

Regulation and Function of Matrix Metalloproteinase-13 in Cancer Progression and Metastasis.

Matrix metalloproteinase-13 (MMP-13) is a member of the Matrix metalloproteinases (MMPs) family of endopeptidases. MMP-13 is produced in low amounts and is well-regulated during normal physiological conditions. Its expression and secretion are, however, increased in various cancers, where it plays multiple roles in tumour progression and metastasis. As an interstitial collagenase, MMP-13 can proteolytically cleave not only collagens I, II and III, but also a range of extracellular matrix proteins (ECMs). Its action causes ECM remodelling and often leads to the release of various sequestered growth and angiogenetic factors that promote tumour cell growth, invasion and angiogenesis. This review summarizes our current understanding of the regulation of MMP-13 expression and secretion and discusses the actions of MMP-13 in cancer progression and metastasis.

Gastric metastasis before diagnosis of primary invasive lobular breast carcinoma: a rare case presentation from Pakistan.

Metastatic spread of invasive lobular breast carcinoma to stomach is rare especially before diagnosis of primary breast cancer. Incorrect diagnosis might result in delay of appropriate treatment for breast cancer. Recognition of this possibility enables better clinical management. A 62-year-old female presented with upper gastrointestinal symptoms and weight loss and was referred to a gastroenterologist for investigation. At the time of initial diagnosis of stomach cancer, patient was asymptomatic for breast cancer. Multiple gastric biopsies taken showed features suspicious of metastatic breast cancer. Consequently, the initial provisional diagnosis of stomach cancer changed into metastatic invasive lobular breast carcinoma. These findings were corroborated radiologically. The patient was treated with letrozole and zoledronic acid as first-line therapy for one year. Residual metastatic breast cancer was present in the gastric mucosa. The patient was treated with endocrine therapy containing ribociclib and treatment was ineffective confirmed by PET-CT scan. But her symptoms have resolved completely despite her presentation with stage IV. We present rare case of initial presentation of gastric metastasis before diagnosis of a primary invasive lobular breast carcinoma. Correct diagnosis and appropriate treatment were accomplished through initial clinical suspicion, accurate histological examination, and endoscopy together with analysis of disease-specific biomarkers.

Appearance of peanut agglutinin in the blood circulation after peanut ingestion promotes endothelial secretion of metastasis-promoting cytokines.

Peanut agglutinin (PNA) is a carbohydrate-binding protein in peanuts that accounts for ~0.15% peanut weight. PNA is highly resistant to cooking and digestion and is rapidly detectable in the blood after peanut consumption. Our previous studies have shown that circulating PNA mimics the actions of endogenous galactoside-binding protein galectin-3 by interaction with tumour cell-associated MUC1 and promotes circulating tumour cell metastatic spreading. The present study shows that circulating PNA interacts with micro- as well as macro-vascular endothelial cells and induces endothelial secretion of cytokines MCP-1 (CCL2) and IL-6 in vitro and in vivo. The increased secretion of these cytokines autocrinely/paracrinely enhances the expression of endothelial cell surface adhesion molecules including integrins, VCAM and selectin, leading to increased tumour cell-endothelial adhesion and endothelial tubule formation. Binding of PNA to endothelial surface MCAM (CD146), via N-linked glycans, and subsequent activation of PI3K-AKT-PREAS40 signalling is here shown responsible for PNA-induced secretion of MCP-1 and IL-6 by vascular endothelium. Thus, in addition to its influence on promoting tumour cell spreading by interaction with tumour cell-associated MUC1, circulating PNA might also influence metastasis by enhancing the secretion of metastasis-promoting MCP-1 and IL-6 from the vascular endothelium.

Long-Term Iron Deficiency and Dietary Iron Excess Exacerbate Acute Dextran Sodium Sulphate-Induced Colitis and Are Associated with Significant Dysbiosis.

BACKGROUND: Oral iron supplementation causes gastrointestinal side effects. Short-term alterations in dietary iron exacerbate inflammation and alter the gut microbiota, in murine models of colitis. Patients typically take supplements for months. We investigated the impact of long-term changes in dietary iron on colitis and the microbiome in mice. METHODS: We fed mice chow containing differing levels of iron, reflecting deficient (100 ppm), normal (200 ppm), and supplemented (400 ppm) intake for up to 9 weeks, both in absence and presence of dextran sodium sulphate (DSS)-induced chronic colitis. We also induced acute colitis in mice taking these diets for 8 weeks. Impact was assessed (i) clinically and histologically, and (ii) by sequencing the V4 region of 16S rRNA. RESULTS: In mice with long-term changes, the iron-deficient diet was associated with greater weight loss and histological inflammation in the acute colitis model. Chronic colitis was not influenced by altering dietary iron however there was a change in the microbiome in DSS-treated mice consuming 100 ppm and 400 ppm iron diets, and control mice consuming the 400 ppm iron diet. Proteobacteria levels increased significantly, and Bacteroidetes levels decreased, in the 400 ppm iron DSS group at day-63 compared to baseline. CONCLUSIONS: Long-term dietary iron alterations affect gut microbiota signatures but do not exacerbate chronic colitis, however acute colitis is exacerbated by such dietary changes. More work is needed to understand the impact of iron supplementation on IBD. The change in the microbiome, in patients with colitis, may arise from the increased luminal iron and not simply from colitis.

Appendiceal goblet cell carcinomas have poor survival despite completion surgery.

PURPOSE: Appendiceal goblet cell carcinomas (aGCCs) are rare but aggressive tumours associated with significant mortality. We retrospectively reviewed the outcomes of aGCC patients treated at our tertiary referral centre. METHODS: We analysed aGCC patients, diagnosed between 1990-2016, assessing the impact of completion surgery and tumour factors on survival. Survival was assessed using Kaplan-Meier analysis. RESULTS: We identified 41 patients (23 F, 18 M); median age 61 (range 27-79) years. Mean tumour size was 10.5 (range 0.5-50) mm; most tumours were located in the appendiceal tip (n = 18, 45%). Appendicectomy was the index surgery in 32 patients, 24 of whom subsequently underwent completion surgery at median 3 (range 1.3-13.3) months later. Histology from completion surgery showed residual disease in 8 patients: nodal disease (n = 2) or residual tumour (n = 6). Index surgery for the rest was either colectomy (n = 7) or cytoreductive surgery plus intraperitoneal chemotherapy (CRS-HIPEC) (n = 1). Index and completion surgery had 0% mortality and 2.5% morbidity. Overall and recurrence-free survival were not significantly affected by tumour grade or completion surgery. Disease recurred in 9 patients after a median follow-up of 57.0 (4.6-114.9) months; 7 of these patients died during follow-up. Recurrences were treated with CRS-HIPEC (n = 1), palliative chemotherapy (n = 3) or supportive care (n = 5). Five- and ten- year overall survival were 85.3% and 62.3% respectively; 5-year and 10-year recurrence-free survival were 73.6% and 50.6%. CONCLUSION: The prognosis of aGCCs remains relatively poor. Completion surgery did not prevent recurrence or improve survival, but this needs to be verified with a larger patient cohort. The high mortality associated with tumour recurrence questions current treatment recommendations.

The impact of lymph node metastases and right hemicolectomy on outcomes in appendiceal neuroendocrine tumours (aNETs).

INTRODUCTION: European Neuroendocrine Tumour Society (ENETS) recommends managing appendiceal neuroendocrine tumours (aNET) with appendicectomy and possibly completion right hemicolectomy (CRH). However, disease behaviour and survival patterns remain uncertain. MATERIALS AND METHODS: We retrospectively assessed the impact of lymph nodes and CRH on outcomes, including survival, in all aNET patients diagnosed between 1990 and 2016. RESULTS: 102 patients (52F, 50 M), median age 39.4 (range 16.3-81.1) years, were diagnosed with aNET. Mean tumour size was 12.7 (range 1-60) mm, most sited in appendiceal tip (63%). Index surgery was appendicectomy in 79% of cases while the remainder underwent colectomy. CRH performed in 30 patients at a median 3.2 (range 1.4-9.8) months post-index surgery yielded residual disease in nine: lymph nodes (n = 8) or residual tumour (n = 1). Univariate logistic regression showed residual disease was significantly predicted by tumour size ≥2 cm (p = 0.020). Four patients declined CRH, but did not suffer relapse or reduced survival. One patient developed recurrence after 16.5 years of follow-up and another patient developed a second neuroendocrine tumour after 18.8 years follow-up. There were 5 deaths; one being aNET-related. 5-year and 10-year overall survival were 99% and 92% respectively; 5-year and 10-year relapse-free survival were 98% and 92% respectively. Only 5-year relapse-free survival was affected by ENETS stage (p = 0.002). CONCLUSION: aNETs are indolent with very high rates of overall and relapse-free survival. Recurrence is rare, and in this series only occurred decades later, making a compelling case for selective surveillance and follow-up. The significance of positive lymph nodes and the necessity for completion right hemicolectomy remain unclear.

Systematic review: management of localised low-grade upper gastrointestinal neuroendocrine tumours.

BACKGROUND: Neuroendocrine tumours (NETs) of the stomach and duodenum are rare, but are increasing in incidence. Optimal management of localised, low-grade gastric and duodenal NETs remains controversial. AIMS: To systematically review recent literature that has evaluated the management of localised low-grade gastric and duodenal NETs. METHODS: A systematic literature search was conducted. Articles were screened and eligible articles fully assessed. Additional articles were identified through the included articles' reference lists. RESULTS: Several relevant retrospective case series were identified, but there was considerable heterogeneity between studies and they reported a variety of parameters. Type I gastric NETs had an excellent prognosis and conservative management approaches such as endoscopic surveillance/resection were appropriate in most cases. Many type III gastric NETs were low grade and appeared to have a better prognosis than has previously been appreciated. Endoscopic rather than surgical resection was therefore effective in some patients who had small, low-grade tumours. Duodenal NETs were more heterogenous. Endoscopic resection was generally safe and effective in patients who had small, low-grade, nonfunctional, non-ampullary tumours. However, some patients, especially those with larger or ampullary duodenal NETs, required surgical resection. CONCLUSIONS: Most type I gastric NETs behave indolently and surgical resection is only rarely indicated. Some type III gastric and duodenal NETs have a worse prognosis, but selected patients who have small, localised, nonfunctional, low-grade tumours are adequately and safely treated by endoscopic resection. Due to the complexity of this area, a multidisciplinary approach to management is strongly recommended.

Matrix metalloproteinase (MMP)-7 in Barrett's esophagus and esophageal adenocarcinoma: expression, metabolism, and functional significance.

Matrix metalloproteinase (MMP)-7, unlike many MMPs, is typically expressed in epithelial cells. It has been linked to epithelial responses to infection, injury, and tissue remodeling including the progression of a number of cancers. We have now examined how MMP-7 expression changes in the progression to esophageal adenocarcinoma (EAC), and have studied mechanisms regulating its expression and its functional significance. Immunohistochemistry revealed that MMP-7 was weakly expressed in normal squamous epithelium adjacent to EAC but was abundant in epithelial cells in both preneoplastic lesions of Barrett's esophagus and EAC particularly at the invasive front. In the stroma, putative myofibroblasts expressing MMP-7 were abundant at the invasive front but were scarce or absent in adjacent tissue. Western blot and ELISA revealed high constitutive secretion of proMMP-7 in an EAC cell line (OE33) that was inhibited by the phosphatidylinositol (PI) 3-kinase inhibitor LY294002 but not by inhibitors of protein kinase C, or MAP kinase activation. There was detectable proMMP-7 in cultured esophageal myofibroblasts but it was undetectable in media. Possible metabolism of MMP-7 by myofibroblasts studied by proteomic analysis indicated degradation via extensive endopeptidase, followed by amino- and carboxpeptidase, cleavages. Myofibroblasts exhibited increased migration and invasion in response to conditioned media from OE33 cells that was reduced by MMP-7 knockdown and immunoneutralization. Thus, MMP-7 expression increases at the invasive front in EAC which may be partly attributable to activation of PI 3-kinase. Secreted MMP-7 may modify the tumor microenvironment by stimulating stromal cell migration and invasion.

Analysis of clinical isolates of Helicobacter pylori in Pakistan reveals high degrees of pathogenicity and high frequencies of antibiotic resistance.

BACKGROUND: Antibiotic resistance in Helicobacter pylori contributes to failure in eradicating the infection and is most often due to point and missense mutations in a few key genes. METHODS: The antibiotic susceptibility profiles of H. pylori isolates from 46 Pakistani patients were determined by Etest. Resistance and pathogenicity genes were amplified, and sequences were analyzed to determine the presence of mutations. RESULTS: A high percentage of isolates (73.9%) were resistant to metronidazole (MTZ), with considerable resistance to clarithromycin (CLR; 47.8%) and amoxicillin (AML; 54.3%) also observed. Relatively few isolates were resistant to tetracycline (TET; 4.3%) or to ciprofloxacin (CIP; 13%). However, most isolates (n = 43) exhibited resistance to one or more antibiotics. MTZ-resistant isolates contained missense mutations in oxygen-independent NADPH nitroreductase (RdxA; 8 mutations found) and NADH flavin oxidoreductase (FrxA; 4 mutations found). In the 23S rRNA gene, responsible for CLR resistance, a new point mutation (A2181G) and 4 previously reported mutations were identified. Pathogenicity genes cagA, dupA, and vacA s1a/m1 were detected frequently in isolates which were also found to be resistant to MTZ, CLR, and AML. A high percentage of CagA and VacA seropositivity was also observed in these patients. Phylogenetic analysis of partial sequences showed uniform distribution of the 3' region of cagA throughout the tree. CONCLUSIONS: We have identified H. pylori isolates in Pakistan which harbor pathogenicity genes and worrying antibiotic resistance profiles as a result of having acquired multiple point and missense mutations. H. pylori eradication regimens should therefore be reevaluated in this setting.

Increased circulation of galectin-3 in cancer induces secretion of metastasis-promoting cytokines from blood vascular endothelium.

PURPOSE: Cytokines such as interleukin (IL)-6 and granulocyte colony-stimulating factor (G-CSF) are important metastasis promoters. This study has investigated the functional significance of the increased circulation of galectin-3, a common feature in patients with cancer and in particular those with metastasis, on cytokine secretion from the blood vascular endothelium in cancer. EXPERIMENTAL DESIGN: The effects of galectin-3 on secretion of cytokines from human microvascular lung endothelial cells were assessed in vitro by cytokine array and in vivo in mice. The consequences of galectin-3-induced cytokine secretion on endothelial cell behaviors were determined, and the relationship between the levels of circulating galectin-3 and cytokines in patients with colorectal cancer with and without metastasis was investigated. RESULTS: Galectin-3 at pathologic concentrations found in patients with cancer induces secretion of IL-6, G-CSF, sICAM-1, and granulocyte macrophage colony-stimulating factor from blood vascular endothelial cells in vitro and in mice. These cytokines autocrinely/paracrinely interact with the vascular endothelium to increase the expressions of endothelial cell surface adhesion molecules integrinα(v)ß(1), E-selectin, ICAM-1, and VCAM-1, resulting in increased cancer cell-endothelial adhesion and increased endothelial cell migration and tubule formation. In patients with metastatic colon cancer, higher serum galectin-3 levels correlated significantly with increased serum G-CSF, IL-6, and sICAM1 concentrations. CONCLUSION: The increased circulation of galectin-3 in patients with cancer induces secretion of several metastasis-promoting cytokines from the blood vascular endothelium that enhances endothelial cell activities in metastasis. Targeting the actions of circulating galectin-3 in patients with cancer therefore represents a promising therapeutic strategy to reduce metastasis and improve survival.

Inactivating cholecystokinin-2 receptor inhibits progastrin-dependent colonic crypt fission, proliferation, and colorectal cancer in mice.

Hyperproliferation of the colonic epithelium, leading to expansion of colonic crypt progenitors, is a recognized risk factor for colorectal cancer. Overexpression of progastrin, a nonamidated and incompletely processed product of the gastrin gene, has been shown to induce colonic hyperproliferation and promote colorectal cancer in mice, but the mechanism of pathogenesis has not been defined. Cholecystokinin-2 receptor (CCK2R) is the primary receptor for cholecystokinin (CCK) and amidated gastrin. Here, we show that Cck2r was expressed in murine colonic crypts and upregulated in the transgenic mice that overexpress human progastrin. Murine deletion of Cck2r abrogated progastrin-dependent increases in colonic proliferation, mucosal thickness, and beta-catenin and CD44 expression in the colon tumor. In addition, either deletion or antagonism of Cck2r resulted in the inhibition of progastrin-dependent increases in progenitors expressing doublecortin and CaM kinase-like-1 (DCAMKL1), stem cells expressing leucine rich repeat-containing G protein-coupled receptor 5 (LgR5), and colonic crypt fission. Furthermore, in the azoxymethane mouse model of colorectal carcinogenesis, Cck2r deletion in human progastrin-overexpressing mice resulted in markedly decreased aberrant crypt foci formation and substantially reduced tumor size and multiplicity. Taken together, these observations indicate that progastrin induces proliferative effects, primarily in colonic progenitor cells, through a CCK2R-dependent pathway. Moreover, our data suggest that CCK2R may be a potential target in the treatment or prevention of colorectal cancer.