A K-ras oncogene increases resistance to sulindac-induced apoptosis in rat enterocytes

BACKGROUND & AIMS: Mutations of c-K-ras occur commonly in colonic neoplasms. The aim of this study was to determine how c-K-ras mutations alter the responses to the chemopreventive agent sulindac. METHODS: The parental rat intestinal cell line IEC-18 and c-K-ras-transformed derivatives were treated with sulindac sulfide. Cell cycle distribution was determined by flow-cytometric analysis (fluorescence-activated cell sorter), apoptosis by DNA fragmentation (laddering), flow cytometry, and microscopy, and changes in gene expression by immunoblotting. RESULTS: Sulindac sulfide inhibited cell growth and induced apoptosis in a time- and dose-dependent manner more rapidly in and at lower concentrations in parental cells than ras-transformed cells. Expression of the sulindac sulfide arrested cells in G0/G1, but cells entered apoptosis throughout the cell cycle. Proapoptotic protein Bak was relatively high in untreated parental cells and increased markedly after sulindac sulfide but was low in untreated ras-transformed cells and did not increase after sulindac sulfide. Expression of other Bcl-2 family members was unchanged after sulindac sulfide. However, sulindac sulfide reduced levels of cyclin D1 protein and cyclin E- and cyclin D1- associated kinase activity. CONCLUSIONS: c-K-ras-transformed enterocytes are relatively resistant to sulindac sulfide-induced growth inhibition and apoptosis, which may result from specific reduction of bak expression. (Gastroenterology 1997 Dec;113(6):1892-900)     

Overexpression of the major vault transporter protein lung-resistance protein predicts treatment outcome in acute myeloid leukemia

The monoclonal antibody LRP56 recognizes a 110-kD major vault protein (lung-resistance protein [LRP]) overexpressed in several P-glycoprotein- negative (Pgp-), multidrug resistant tumor cell lines. To determine the frequency of LRP overexpression, its prognostic significance, and its relation to Pgp, we analyzed bone marrow specimens from 87 consecutive patients with acute leukemia. Diagnoses included de novo acute myeloid leukemia (AML; 21 patients), leukemia arising from an antecedent hematologic disorder or prior cytotoxic therapy (secondary AML; 27 patients), AML in relapse (29 patients), and blast phase of chronic myeloid leukemia (CML-BP; 10 patients). A granular cytoplasmic staining pattern was detected by immunocytochemistry in 32 (37%) cases, including 7 (33%) de novo AML, 13 (48%) secondary AML, 11 (38%) relapsed AML, and 1 of 10 CML-BP. Among 66 evaluable patients with AML, LRP overexpression was associated with an inferior response to induction chemotherapy (P = .0017). Remissions were achieved in 35% of LRP+ patients as compared with 68% of LRP- patients. Although Pgp adversely affected response in univariate analysis (P = .0414), only LRP had independent prognostic significance when compared in a logistic regression model (P = .0046). Differences in remission duration (P = .075) and overall survival (P = .058) approached significance only for LRP. Sequential specimens from remitting patients receiving treatment with the Pgp modulator cyclosporin-A showed emergence of the LRP phenotype despite a decrease or loss of Pgp at the time of treatment failure (P =.0304). Significant associations were observed between LRP and age greater than 55 years (P = .017), Pgp (P = .040), and prior treatment with mitoxantrone (P = .020) but not with CD34. These findings indicate that overexpression of the novel transporter protein LRP is an important predictor of treatment outcome in AML.     

Phorbol ester stimulation increases sickle erythrocyte adherence to endothelium: a novel pathway involving alpha 4 beta 1 integrin receptors on sickle reticulocytes and fibronectin

Sickle-cell adherence to endothelium has been hypothesized to initiate or contribute to microvascular occlusion and pain episodes. Adherence involves plasma proteins, endothelial-cell adhesion molecules, and receptors on sickle erythrocytes. It has previously been reported that sickle reticulocytes express the alpha 4 beta 1 integrin receptor and bind to cytokine-activated endothelium via an alpha 4 beta 1/vascular- cell adhesion molecule-1 (VCAM-1) interaction. To elucidate other roles for alpha 4 beta 1 in sickle-cell adherence, the ability of activated alpha 4 beta 1 to promote adhesion to endothelium via a ligand different than VCAM-1 was explored. Adherence assays were performed under dynamic conditions at a shear stress of 1 dyne/cm2. Preincubation of sickle erythrocytes with phorbol 12,13-dibutyrate (PDBu) increased adherence of sickle cells eightfold as compared with untreated sickle cells. Normal erythrocytes, whether treated with PDBu or not, did not adhere to the endothelium. Activating anti-beta 1 antibodies 4B4 and 8A2 also increased the adhesion of sickle, but not normal, red blood cell (RBC) adhesion to endothelium. Anti-alpha 4 antibodies HP1/2 and HP2/1, inhibitory antibody 4B5, or an RGD peptide inhibited sickle-cell adherence induced by PDBu. Additional studies were undertaken to examine if fibronectin, a ligand for activated alpha 4 beta 1, was involved in PDBu-induced sickle erythrocyte adherence. Adherence of PDBu-treated sickle cells was completely inhibited by the CS-1 peptide of fibronectin. Fibronectin was detected on the surface of washed endothelium using an antifibronectin antibody in enzyme-linked immunosorbent assays. Antifibronectin antibody pretreatment of endothelial cells inhibited PDBu-induced adherence by 79% +/- 17%. Incubation of sickle RBCs with exogenous fibronectin after PDBu treatment inhibited adherence 86% +/- 8%. Taken together, these data suggest that endothelial-bound fibronectin mediates adherence of PDBu- treated sickle cells. Interleukin-8 (IL-8), a chemokine released in response to bacterial infection, viral infection, or other injurious agents, and known to activate integrins, also increased adherence of sickle erythrocytes to endothelial cells via fibronectin. This novel adherence pathway involving sickle-cell alpha 4 beta 1 activated by PDBu or IL-8 may therefore be relevant in vivo at vascular sites that produce IL-8 or similar agonists in response to vascular injury or immune activation. These observations describe ways in which inflammation and immune responses cause vasoocclusive complications in sickle-cell disease.     

Palliative care for patients with gastrointestinal cancer dying under surgical care: A case for acute palliative care units?

Background and aimsPatients with advanced gastrointestinal cancer may present late to hospital services and die under surgical care. The aim of this study was to examine end of life care in patients dying of gastrointestinal cancer in Scottish hospital surgical wards.MethodsThe Scottish Audit of Surgical Mortality prospectively peer reviews all inpatient deaths under the care of a consultant surgeon. Patients who died with gastrointestinal cancer under surgical care from 1994 to 2006 were evaluated for operative interventions, adverse events, and palliative care provision. Data was compared with inpatient data from the Information Statistics Division of NHS Scotland.ResultsA total of 8019 patients died with gastrointestinal cancer on a surgical ward over 12 years. For 4350 (54%), no operation or endoscopy was performed during the final admission and adverse events were identified in only 86 (2%) of these patients, most commonly due to a complication of an interventional procedures. Specialist palliative care was provided to 57% of patients and was not influenced by cancer site.ConclusionA substantial proportion of patients die with gastrointestinal cancer on general surgical wards without operative or endoscopic intervention and may receive better end of life care in an acute palliative care setting.     

Reovirus type 1 and type 3 differ in their binding to isolated intestinal epithelial cells

Binding of reovirus type 1 to dispersed villus cells from the small intestine was found to be specific for the basolateral membrane. Reovirus type 3 did not bind to any surface of small intestinal epithelial cells, but did bind to intra-epithelial lymphocytes. Using reovirus genetic reassortants, it was shown that the viral attachment polypeptide, encoded by the S1 genome segment of reovirus type 1 is essential for reovirus specific immunofluorescence to villus epithelial cells. In addition, the binding of reovirus type 1 to intestinal cells is saturable. Competition for the binding of 125I-labeled reovirus type 1 was demonstrated with unlabeled reovirus type 1 but not unlabeled reovirus type 3. This indicates that the intestinal epithelial receptor for reovirus is not shared by reovirus serotypes 1 and 3, and infection of intestinal epithelial cells by reovirus type 3 may be limited due to a failure of virus to bind.     

Hepatitis B virus infections transmitted from retarded children to their families during brief home exposure

Hepatitis B virus (HBV) infection is endemic among institutionalized retarded patients, who usually have mild, anicteric hepatitis following nonparenteral exposure. We evaluated the risk of HBV infection (as evidenced by serologic studies) among their contacts, including noninstitutional caretakers, during brief home exposure. Caretakers shaved, bathed, and changed diapers for five patients during home visits or foster home placements. Seven of the 14 caretakers, who were exposed for 3-12 months, developed antibodies (anti-HBc and/or anti-HBs). A mother and her daughter's caretaker were found to have asymptomatic acute HBV infection, and the mother developed antibodies to HBs, HBc, and HBe. In a second household, another caretaker became anti-HBs-positive. Only one of nine play contacts and none of seven casual contacts had markers of past or present HBV infection. The study was a unique opportunity to retrospectively and prospectively monitor HBV transmission. Our results show that noninstitutional caretakers deserve the protection of HBV vaccine to diminish the potential for chronic infection and transmission of HBV infection.