Abstract
The role of the retinoblastoma gene (RB1) in human gastric carcinogenesis is yet to be clarified. We report on the analysis of RB1 structure and protein (pRB) expression in gastric carcinomas using Southern blotting, Western blotting and immunohistochemistry. The relationship between pRB expression and cell proliferation was assessed by a proliferation marker (PCNA) in a subset of cases. Non-neoplastic mucosas were studied, as controls, by the same methodology. We found a close relationship between pRB expression and PCNA in non-neoplastic mucosas as well as in gastric carcinomas. All tumours were immunohistochemically positive for pRB, although with a variable proportion of non-immunoreactive cells. Carcinomas of the diffuse type showed absence of pRB expression in a larger proportion of neoplastic cells than carcinomas of the intestinal type (P < 0.05). Analysis of the RB1 structure using probe p68RS2.0 revealed allelic imbalance in 29% of informative cases. No homozygous deletions and/or rearrangements were detected with p68RS2.0 and cDNA probes. Western analysis revealed no abnormal patterns of pRB. Our data therefore suggest that major alterations affecting the RB1 gene are rather infrequent in human gastric carcinomas.
Highlights
Retinoblastoma gene structure and product expression in human gastric carcinomasDepartments of 'Pathology and 2Medical Genetics, Medical School and IPA TIMUP, University of Porto, Portugal
Sm.mmary The role of the retinoblastoma gene (RBI) in human gastric carcinogenesis is yet to be clarified
We report on the analysis, using immunohistochemistry, Western blotting and Southern blotting, of the structure and expression of RBI in human gastric carcinomas comparing the results obtained with the clinicopathological features and proliferation activity of the tumours
Summary
Departments of 'Pathology and 2Medical Genetics, Medical School and IPA TIMUP, University of Porto, Portugal. We report on the analysis of RB1 structure and protein (pRB) expression in gastric carcinomas using Southern blotting, Western blotting and immunohistochemistry. RBI inactivation has been observed in other malignant tumours, namely cancers of the breast (Lee et al, 1988; Varley et al, 1989), bladder (Horowitz et al, 1989; Ishikawa et al, 1991; Cairns et al, 1991), prostate (Bookstein et al, 1990) and lung (Harbour et al, 1988; Yokota et al, 1988; Hensel et al, 1990), as well as in several types of leukaemia (Furukawa et al, 1991). We report on the analysis, using immunohistochemistry, Western blotting and Southern blotting, of the structure and expression of RBI in human gastric carcinomas comparing the results obtained with the clinicopathological features and proliferation activity of the tumours
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