IMMUNOHISTOCHEMICAL EVIDENCE OF ABERRANT BCL-2 PROTEIN EXPRESSION IN GASTRIC EPITHELIAL DYSPLASIA

Background. bcl-2 protein encoded by the proto-oncogene bcl-2 confers to the cell a survival advantage by inhibiting apoptosis. Its aberrant expression has been reported in lymphomas and lung carcinoma. To dete rmine if bcl-2 plays a role in the gastric carcinogenic sequence, the authors studied bcl-2 expression in gastric epithelial dysplasia (GED) and chronic atrophic gastritis with intestinal metaplasia (CAG-IM). M ethods. Immunohistochemical staining using monoclonal bcl-2 protein an tibody, clone 124, was performed on archival material. ResuIts. bcl-2 staining was seen in 13 of 16 GEDs (81%). The staining was heterogenou s, suggesting that within the dysplastic epithelium, some cellular clo nes may have a survival advantage. When noted, the staining in IM was located in the proliferative zone, but some positivity could also be n oted higher up along the cellular escalator. Normal gastric mucosa sta ined in the proliferative zone. Conclusions. The authors demonstrated that bcl-2 expression is noted in GED as well as in the extended proli ferative zone of CAG-IM. This suggests that prolonged cell survival du e to inhibition of apoptosis is instrumental in addition to increased cellular proliferation in the altered cellular homeostasis of the gast ric carcinogenic sequence. Whether bcl-2 protein aberrant expression i s an independent process or inherent to immaturity of the cells produc ed by the increased proliferation awaits further studies.