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Bcl‐2 protein expression in carcinomas originating from the follicular epithelium of the thyroid gland
Author(s) -
Pilotti Silvana,
Collini Paola,
Rilke Franco,
Cattoretti Giorgio,
Del Bo Romualdo,
Pierotti Marco A.
Publication year - 1994
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.1711720408
Subject(s) - thyroid , pathology , immunostaining , thyroglobulin , epithelium , immunocytochemistry , adenoma , follicular phase , thyroid carcinoma , biology , immunohistochemistry , medicine , endocrinology
The bcl‐2 product has been related to the block of programmed cell death (apoptosis) both in lymphoid and in epithelial cells. The pathological expression of bcl‐2 has been investigated mainly in haematological malignancies. Here we have investigated bcl‐2 expression in a model of epithelial tumours represented by the spectrum of carcinomas arising from the follicular epithelium of the human thyroid gland. The analysis was carried out by immunocytochemistry on archival material using monoclonal antibodies against bcl‐2 and thyroglobulin (Tg) on consecutive sections of 94 well‐differentiated carcinomas (WDCs), 19 poorly differentiated carcinomas (PDCs), and 22 undifferentiated carcinomas (UCs) of the thyroid gland. In a subset of 5 cases of UC showing a differentiated component (UC‐D), the expression of p53 protein was also investigated. As controls, fetal and adult normal thyroid glands and adenomas were analysed. bcl‐2 expression was detected in 74 of 94 cases (78·7 per cent) of WDC, 16 of 19 cases (84·2 per cent) of PDC, and 3 of 22 cases (13·6 per cent) of UC. Simultaneous expression of bcl‐2 protein and Tg was observed in 74 of 94 cases (78·7 per cent) of WDC, 13 of 19 cases (68·4 per cent) of PDC, and in no case of UC. bcl‐2 and Tg immunostaining was detected in all fetal and normal thyroid glands as well as in the adenoma specimens examined. In the subset of UC‐D, mutual exclusion of bcl‐2 and p53 expression was observed in the undifferentiated and differentiated components (p53 but not bcl‐2 expressed in the former). Our data indicate that within the spectrum of thyroid carcinomas bcl‐2 expression, similarly to Tg, is strictly correlated with cell differentiation and that its abrogation is restricted to UCs, in which alterations of the p53 gene represent a late genetic event related to tumour progression.