Cell surface heparan sulfate proteoglycans control adhesion and invasion of breast carcinoma cells

Background

Cell surface proteoglycans interact with numerous regulators of cell behavior through their glycosaminoglycan chains. The syndecan family of transmembrane proteoglycans are virtually ubiquitous cell surface receptors that are implicated in the progression of some tumors, including breast carcinoma. This may derive from their regulation of cell adhesion, but roles for specific syndecans are unresolved.

Methods

The MDA-MB231 human breast carcinoma cell line was exposed to exogenous glycosaminoglycans and changes in cell behavior monitored by western blotting, immunocytochemistry, invasion and collagen degradation assays. Selected receptors including PAR-1 and syndecans were depleted by siRNA treatments to assess cell morphology and behavior. Immunohistochemistry for syndecan-2 and its interacting partner, caveolin-2 was performed on human breast tumor tissue arrays. Two-tailed paired t-test and one-way ANOVA with Tukey’s post-hoc test were used in the analysis of data.

Results

MDA-MB231 cells were shown to be highly sensitive to exogenous heparan sulfate or heparin, promoting increased spreading, focal adhesion and adherens junction formation with concomitantly reduced invasion and matrix degradation. The molecular basis for this effect was revealed to have two components. First, thrombin inhibition contributed to enhanced cell adhesion and reduced invasion. Second, a specific loss of cell surface syndecan-2 was noted. The ensuing junction formation was dependent on syndecan-4, whose role in promoting actin cytoskeletal organization is known. Syndecan-2 interacts with, and may regulate, caveolin-2. Depletion of either molecule had the same adhesion-promoting influence, along with reduced invasion, confirming a role for this complex in maintaining the invasive phenotype of mammary carcinoma cells. Finally, both syndecan-2 and caveolin-2 were upregulated in tissue arrays from breast cancer patients compared to normal mammary tissue. Moreover their expression levels were correlated in triple negative breast cancers.

Conclusion

Cell surface proteoglycans, notably syndecan-2, may be important regulators of breast carcinoma progression through regulation of cytoskeleton, cell adhesion and invasion.     

Opposite sorting of tissue factor in human umbilical vein endothelial cells and Madin-Darby canine kidney epithelial cells

Tissue factor (TF) is a 48-kD transmembrane glycoprotein that triggers the extrinsic pathway of blood coagulation by interacting with the plasma coagulation factor VII (FVII). TF is also a true receptor in that a cellular signal is generated when activated FVII (FVIIa) binds to TF. For both of these functions, the cellular surface distribution of TF is important, since FVII is primarily available on the apical side of vascular endothelial cells and on the basolateral side of epithelial cells lining the internal and external surfaces. We show that in endothelial cells, TF (both antigen and procoagulant activity) is sorted to the apical surface, whereas in wild-type and stably transfected Madin-Darby canine kidney epithelial cells (MDCK), which form tight junctions and express TF constitutively, TF antigen is on the basolateral surface. No significant clotting activity is detectable on this surface. Truncated TF (cytoplasmic tail residues 246 to 263 deleted) is sorted as wild-type in MDCK cells.     

Acute appendicitis in the setting of Clostridium difficile colitis: case report and review of the literature

A 72-year-old man was hospitalized for exacerbation of chronic obstructive pulmonary disease and was treated with oral prednisone and 7 days of moxifloxacin. Five days after completing the antibiotic course, he developed watery diarrhea and diffuse, crampy abdominal pain. On presentation he was afebrile, and abdominal examination revealed diffuse tenderness without peritoneal signs. Stool tested positive for Clostridium difficile toxin A by enzyme-linked immunosorbent assay. Despite starting oral metronidazole, the patient developed a fever of 101.2 degrees F 36 hours after his initial episode of diarrhea, 12 hours after admission. His abdominal pain intensified and became localized to the right and left lower quadrants. Computed tomography scan revealed both a thickened cecal wall and an edematous appendix with ileocecal stranding consistent with appendicitis. Appendectomy was performed, and the appendix was found to be suppurative in appearance and nonperforated. The cecum had mild edema and erythema, whereas the colon and rectum were grossly unaffected. Pathology examination revealed exudative material in the appendiceal lumen and a diffuse transmural inflammatory cell infiltrate. The patient had an uneventful recovery and continued to improve on oral metronidazole. Although Clostridium difficile colitis and appendicitis are each very common independently, C. difficile as an etiology of appendicitis is exceedingly rare. A review of the literature revealed 2 prior cases. We speculate that this association is underdiagnosed, because milder cases might respond to antibiotic therapy alone, and severe cases might involve the entire colon and require total colectomy. In each scenario, the involvement of the appendix might be overlooked.     

Use of immunoglobulins in the prevention of GvHD in a xenogeneic NOD/SCID/γc- mouse model

The efficacy of IVIG in preventing GvHD has not been definitely demonstrated clinically. Using a xenogeneic model of GvHD in NOD/SCID/γc- (NSG) mice, we showed that weekly administration of IVIG significantly reduced the incidence and associated mortality of GvHD to a degree similar to CsA. Unlike CsA and OKT3, IVIG were not associated with inhibition of human T-cell proliferation in mice. Instead, IVIG significantly inhibited the secretion of human IL-17, IL-2, IFN-γ and IL-15 suggesting that IVIG prevented GvHD by immunomodulation. Furthermore, the pattern of modification of the human cytokine storm differed from that observed with CsA and OKT3. Finally, in a humanized mouse model of immune reconstitution, in which NSG mice were engrafted with human CD34(+) stem cells, IVIG transiently inhibited B-cell reconstitution, whereas peripheral T-cell reconstitution and thymopoiesis were unaffected. Together these in vivo data raise debate related to the appropriateness of IVIG in GvHD prophylaxis. In addition, this model provides an opportunity to further elucidate the precise mechanism(s) by which IVIG inhibit GvHD.     

Diminished adrenal sensitivity to endogenous and exogenous adrenocorticotropic hormone in critical illness: a prospective cohort study

IntroductionAdrenal dysfunction may represent critical illness-related corticosteroid insufficiency (CIRCI), as evidenced by a diminished cortisol response to exogenous adrenocorticotropic hormone (ACTH), but this concept and its clinical significance remain highly controversial. We studied the adrenal response to exogenous ACTH as a function of the endogenous cortisol-to-ACTH ratio, a measure of adrenal sensitivity, and of clinical variables, during critical illness and recovery from the acute phase.MethodsWe prospectively included 59 consecutive septic and nonseptic patients in the intensive care unit with treatment-insensitive hypotension in whom CIRCI was suspected; patients having received etomidate and prolonged corticosteroids were excluded. An ACTH test (250 μg) was performed, followed by a second test after ≥7 days in acute-phase survivors. Serum total and free cortisol, ACTH, and clinical variables were assessed. Patients were divided according to responses (delta, Δ) of cortisol to ACTH at the first and second tests.ResultsPatients with low (<250 nM) Δ cortisol (n = 14 to 17) had higher baseline cortisol and ACTH but lower cortisol/ACTH ratios than patients with a normal Δ cortisol (≥250 nM) in the course of time. A low Δ cortisol in time was associated with more-severe disease, culture-positive sepsis, and prolonged activated prothrombin time. Results for free cortisol were similar.ConclusionsEven though the pituitary-adrenal axis is activated after stress during critical illness, diminished adrenal sensitivity to endogenous ACTH predicts a low increase of cortisol to exogenous ACTH, suggesting adrenal dysfunction, irrespective of the stage of disease. The data further suggest a role of disease severity and culture-positive sepsis.     

Blood transfusion during cardiac surgery is associated with inflammation and coagulation in the lung: a case control study

Introduction  

Blood transfusion is associated with increased morbidity and mortality in cardiac surgery patients, but cause-and-effect relations remain unknown. We hypothesized that blood transfusion is associated with changes in pulmonary and systemic inflammation and coagulation occurring in patients who do not meet the clinical diagnosis of transfusion-related acute lung injury (TRALI).     

Discarded cigarette butts attract females and kill the progeny of Aedes albopictus

Discarded cigarette butts (DCB) waste occurs worldwide, pollutes landscapes, is unsightly, and results in added debris removal costs. There is, therefore, a great deal of current interest in making use of DCBs in beneficial ways. Despite evidence that DCBs are harmful to water fleas (Daphnia magna), which breed in aquatic environments as do mosquito larvae, their impact on dengue vectors is unknown. We examined whether Aedes albopictus alters its ovipositional responses, larval eclosion, and development in response to presence of DCBs in its habitats. We found oviposition activity in DCB-treated water similar to that of control water and that ovipositional activity in DCB solutions steadily increased over time as those solutions aged to 10 days. Larval eclosion was initially suppressed on day 1 in DCB solution, but increased thereafter to levels similar to control larval eclosion rates. The DCB-water solutions produced significantly higher mortality in both 1st and 2nd instars over control larvae for several days after initial exposure. Mortality rates decreased sharply 3 to 5 days postexposure as DCBs continued to decompose. We found increased survival rates during late development, but daily input of fresh DCBs prevented most young larvae from completing development. Taken together, these observations suggest that decomposing did not deter gravid Ae. albopictus females from ovipositing in treated containers and that DCB solutions had larvicidal effects on early instars. Our results are discussed in the context of DCB use to control container-breeding Ae. albopictus, a competent dengue vector in Asia and other parts of the world.     

Hepatocellular carcinoma and the underlying mechanisms

The incidence of hepatocellular carcinoma is increasing worldwide as well as the associated risk factors, some of which include exposure to aflatoxin B1, Hepatitis B (HBV) virus and hepatitis C (HCV) virus. Mutation of tumour suppressor gene p53 at codon 249^ser at exon 7 has been found to contribute significantly to replication of damaged DNA and subsequent tumour progression. The x gene of HBV (HBx) is the most common open reading frame integrated into the host genome in hepatocellular carcinoma and the integrated HBx is frequently mutated in hepatocellular carcinoma. Mutant HBx proteins still retain their ability to bind to p53 thereby attenuating DNA repair and p53-mediated apoptosis.