Expression of Bcl-2, Bax and p53 proteins in pituitary adenomas: an immunohistochemical study.
OBJECTIVE
Although pituitary adenomas are usually benign lesions, their growth rate is highly variable and unpredictable. Apoptosis appears to be an important process in neoplastic lesions. The purpose of this study was to investigate the expression of apoptosis-related proteins including Bcl-2, bax and p53 in pituitary adenomas and its correlation with hormone function, tumor size, local control, and proliferative activity.


METHODS
The expression of Bcl-2, Bax and p53 proteins and hormonal function were determined in formalin-fixed, paraffin-embedded tissue from 41 untreated pituitary adenomas using immunohistochemistry. The patients were followed for a median of 60 months (range, 12 to 95). Patient charts were reviewed to record tumor recurrence and size. Tumor proliferative activity was assessed by immunohistochemistry using Ki-67 antibody.


RESULTS
Of 41 pituitary adenomas, 26 (63%) were hormone-secreting and 15 (37%) non-functioning, 34 (83%) were macroadenoma and 7 (17%) microadenoma, and 15 (37%) showed local relapse. Six (14%) adenomas were of low proliferative activity, whereas the others (86%) were non-proliferative. Immunohistochemically, 31 adenomas (75%) showed bcl-2 positivity, 37 (90%) bax positivity, and 7 (17%) p53 positivity. Statistical analysis revealed that Bcl-2 protein expression significantly diminished in prolactin-secreting and non-functioning adenomas (P = 0.005 and P = 0.006, respectively), and increased in growth hormone-secreting adenomas (P = 0.003). In addition, expression of bax protein significantly decreased in recurrent tumors, in contrast to p53 protein, which showed a significant increase (P = 0.03 and P = 0.002, respectively).


CONCLUSIONS
We think that apoptosis-related proteins such as Bcl-2, Bax and p53 may be significantly related to hormone function and local control in pituitary adenomas.
Ozer
Erdener
E
Department of Pathology, Dokuz Eylul University, School of Medicine, Inciralti, Izmir, Turkey. erdener.ozer@deu.edu.tr
Canda
M Serefettin
MS
Ulukus
Cagnur
C
Guray
Merih
M
Erbayraktar
Serhat
S
D000236:Adenoma / Q000737:chemistry* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000032:analysis*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D015588:Observer Variation; D010911:Pituitary Neoplasms / Q000737:chemistry* / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis*; D016159:Tumor Suppressor Protein p53 / Q000032:analysis*; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D014408:Biomarkers, Tumor; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein