Expression of Pro-Apoptotic P53 Tumor Suppressor Gene in Pituitary Adenomas: Comparison with Anti-Apoptotic Bcl-2 Oncoprotein

Background: While a great deal of attention has been paid to the study of the control of hormone secretion from Pituitary Adeno-mas (PAs), less attention has been paid to the study of molecular events that underlie the development of these tumors. Objectives: The goal of the present study was to analyze the expression of p53 tumor suppressor gene to allow for its comparison with that of oncoprotein bcl-2 in a series of PA patients followed for a minimum of nine years. Methods: This retrospective study included 51 patients diagnosed with a PA (33 nonfunctioning, 13 acromegaly, 4 Cushing’s disease, and one prolactinoma), who underwent trans-sphenoidal surgery at a single center between 2006 and 2008. P53 and bcl-2 expres-sion were immunohistochemically evaluated and correlated with clinico-radiological and histopathological tumor parameters, as well as post-operative progression/recurrence. Results: Out of 51 tumors, 40 were categorized as typical and 11 as “atypical” PAs. From typical PAs, 28 showed positivity for p53 (cellular mean: 0.99%) and 20 for bcl-2 (cellular mean: 0.58%); from “atypical”, seven had p53 positive cells and six bcl-2 (mean: 2.02%and 0.73%, respectively). Nineteen (37.25%) were positive for the two markers. There were no di erences in the expression of p53 and bcl-2 with regards to age or gender of the patient, size, invasiveness or post-operative tumor recurrence. Conclusions: In the study group, p53 and bcl-2 were abnormally expressed in 68.63% and 50.98% of pituitary tumors, respectively. One-third of PAs were co-expressed across both immunomarkers. The simultaneous genetic complementation of deregulated p53 and bcl-2 is implicated through the apoptosis regulation pathway in the pathogenesis of these tumors.