Immunohistochemical expression of Bcl-2, Bcl-x, and Bax in follicular carcinomas of the thyroid.
Bcl-2, bcl-x, and bax proteins are involved in the regulation of apoptosis. There is limited data on the expression of these proteins in follicular carcinomas (FCs) of the thyroid. A retrospective clinicopathologic review with bcl-2, bcl-x, and bax immunostaining of 34 FCs and 7 follicular adenomas with incomplete capsular penetration (FAICP) was performed. The study included 41 patients (25 females; age range 16 to 84 y, mean 50.9 y). All patients underwent surgical resection. Seven FC patients developed recurrent disease: 1 patient was alive (14.2 y) and 6 patients died with metastatic disease (mean survival 5.9 y). All remaining patients were disease-free (mean follow-up 7.9 y). Only one FAICP recurred (patient alive at 11 y). The remaining patients were disease-free (mean follow-up 6.9 y). Normal thyroid tissue stained positively for bcl-2 and bcl-x, and did not stain with bax. Only 15 tumors (12 FC and 3 FAICP) stained positively for bcl-2. None of the recurrent tumors demonstrated evidence of bcl-2 staining. The majority of tumors stained positively for bax (83%, 29 FC and 5 FAICP) and for bcl-x (93%, 32 FC and 6 FAICP); there was no correlation of staining with outcome. The majority of follicular neoplasms were positive for bax and negative for bcl-2 by immunohistochemistry. Aberrant expression of apoptosis-associated proteins may play a role in the pathogenesis of FC of the thyroid. All recurrent and fatal tumors were negative for bcl-2. These data suggest that the loss of bcl-2 expression may correlate with poorer prognosis.
Haynik
Denise M
DM
Cleveland Clinic Foundation, Cleveland, OH, USA.
Prayson
Richard A
RA
D018263:Adenocarcinoma, Follicular / Q000378:metabolism* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology; D051028:bcl-2-Associated X Protein / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism*
D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein