|Destabilized adhesion in the gastric proliferative zone and c-Src kinase activation mark the development of early diffuse gastric cancer.|
Humar, B; Fukuzawa, R; Blair, V; Dunbier, A; More, H; Charlton, A; Yang, HK; Kim, WH; Reeve, AE; Martin, I; Guilford, P
The initial development of diffuse gastric cancer (DGC) is poorly understood. The study of E-cadherin (CDH1) germ line mutation carriers predisposed to DGC provides a rare opportunity to elucidate the genetic and biological events surrounding disease initiation. Samples from various stages of hereditary and sporadic DGC were investigated to determine general mechanisms underlying early DGC development. Paraffin-embedded tissues from 13 CDH1 mutation carriers and from 10 sporadic early DGC cases were analyzed. Immunofluorescence and immunohistochemistry using differentiation, proliferation, and adhesion markers showed that DGC initiation seems to occur at the proliferative zone (the upper neck) of the gastric epithelium and correlates with absent or reduced expression of junctional proteins (beta-actin, p120, Lin-7). Slow proliferation of neoplastic cells at the upper gastric neck leads to the formation of intramucosal signet-ring cell carcinoma (SRCC) displaying differentiated features. As shown by immunolabeling, invasion from SRCC lesions beyond the gastric mucosa is associated with poor differentiation, increased proliferation, activation of the c-Src system, and an epithelial-mesenchymal transition. Our results provide a molecular description of the early development of DGC and explain the relationship between the two main DGC types, poorly differentiated carcinoma and SRCC: both share their origin, but SRCC develops following cancer cell differentiation and seems relatively indolent in its intramucosal stage.
|Cardiomyocyte cell cycle activation ameliorates fibrosis in the atrium.|
Nakajima, H; Nakajima, HO; Dembowsky, K; Pasumarthi, KB; Field, LJ
MHC-TGFcys33ser transgenic mice have elevated levels of active transforming growth factor (TGF)-beta1 in the myocardium. Previous studies have shown that these animals develop atrial, but not ventricular, fibrosis. Here we show that atrial fibrosis was accompanied with cardiomyocyte apoptosis. Although similar levels of cardiomyocyte apoptosis were present in the right and left atria of MHC-TGFcys33ser hearts, the extent of fibrosis was more pronounced in the right atrium. Thus, additional factors influence the degree of atrial fibrosis in this model. Tritiated thymidine incorporation studies revealed cardiomyocyte cell cycle activity in left atrial cardiomyocytes, but not in right atrial cardiomyocytes. These observations suggested that cardiomyocyte cell cycle activation ameliorated the severity of atrial fibrosis. To directly test this hypothesis, MHC-TGFcys33ser mice were crossed with MHC-cycD2 mice (which have constitutive cardiomyocyte cell cycle activity in the right atrium). Mice inheriting both transgenes exhibited right atrial cardiomyocyte cell cycle activity and a concomitant reduction in the severity of right atrial fibrosis, despite the presence of a similar level of cardiomyocyte apoptosis as was observed in mice inheriting the MHC-TGFcys33ser transgene alone. These data support the notion that cardiomyocyte cell cycle induction can antagonize fibrosis in the myocardium.Full Text Article
|A biotin-avidin technique for the localisation of membrane-bound monoclonal antibodies by low power transmission electron microscopy.|
Volsen, S G
J. Immunol. Methods, 72: 119-26 (1984)
A biotin-avidin horseradish peroxidase system is described for the localisation of membrane-bound monoclonal antibodies by low power transmission electron microscopy. An indirect bridge technique was used, with a biotin-labelled goat anti-mouse immunoglobulin antibody and horseradish peroxidase-conjugated avidin D. The technique provided preparations of high morphological and ultrastructural quality which facilitated accurate cellular identification. Positive immunostaining was specific and precisely defined.