The prognostic role of beclin 1 protein expression in pituitary adenomas

Introduction and Aim: Pituitary adenomas constitute approximately 15% of all intracranial tumors. It is the third most common intracranial neoplasm after glioma and meningioma. Beclin 1 is an autophagy gene with a tumor suppressor role and has been recently recognized with several studies. The aim of this study is to elucidate the relationship between autophagy marker Beclin 1 and clinical and pathological parameters in patients with pituitary adenoma. Materials and Methods: Patients who underwent surgery at Bezmialem Vakıf University Neurosurgery Department between March 2016 – October 2022, had preoperative magnetic resonance imaging in our hospital's system and were diagnosed with pituitary adenoma in the Pathology Department according to WHO 2017 criteria were included in our study. Data on age, gender, pituitary adenoma size, primary and recurrence discrimination, hormonal values, radiological classification findings, pathology evaluation results and immunohistochemical staining characteristics were obtained from the hospital automation system. The relationship between these values and Beclin 1 expression level was evaluated using statistical methods. Results: Out of a total of 78 patients, 75 were macroadenomas and 3 were microadenomas. Thirty-four (45.3%) of the patients with pituitary macroadenoma were female and 41 (54.7%) were male. Beclin 1 expression was not observed in 13 patients. Mild staining was observed in 10 patients, moderate staining in 25 patients, and intense staining in 30 patients. Comparisons were made by grouping Beclin 1 expression status in 4 (0,1,2,3) and 2 (0-1, 2-3) different degrees according to staining status. There was no statistically significant correlation between tumor volume and 4 degrees of Beclin 1 expression level. (p=0.214) However, a statistically significant correlation was found between the tumor volume and the level of Beclin 1 expression examined at 2 degrees (0-1, 2-3). (p=0.044) A significantly higher expression of Beclin 1 was observed in adenomas with a larger tumor volume than in those with a smaller tumor volume. Of the 78 patients we included in the study, 49 had nonfunctional pituitary adenomas, while 29 had functional (hormonal and clinically active) pituitary adenomas. No statistically significant correlation was found between tumor function and the level of Beclin 1 expression, which was examined at 4 degrees. (p=0.051) However, a statistically significant correlation was found between tumor function and Beclin 1 expression level, which was examined at 2 degrees. (p=0.022) The expression level was higher in non-functional tumors than in functional tumors. No statistically significant correlation was found between the radiological classification of Knops pituitary adenoma and the expression level of Beclin 1 examined in 4 degrees. (p=0.315) No statistically significant correlation was found between the radiological classification of Knops pituitary adenoma grouped according to invasion status and the Beclin 1 expression level examined at 4 degrees (p=0.411) and 2 degrees (p=0.170). No statistically significant correlation was found between the Hardy-Wilson modified pituitary adenoma radiological classification and the level of 4 degrees Beclin 1 expression. (p=0.579) No statistically significant correlation was found between the radiological classification of Hardy-Wilson modified pituitary adenoma grouped according to the symmetric-asymmetric suprasellar extension, and the Beclin 1 expression level examined at 4 degrees (p=0.885) and 2 degrees (p=0.456). There was no statistically significant correlation between the presence of primary/recurrent pituitary adenoma and the level of Beclin 1 expression examined at 4 degrees (p=0.233) and 2 degrees (p=0.723). There was no statistically significant correlation between Ki67 proliferation index and 4 degrees of Beclin 1 expression level. (p=0.413) When we divided them into 2 groups with Ki-67 proliferation index below and above 3%, and compared with the Beclin 1 expression level, which was examined at 2 degrees, no statistically significant relationship was found. (p=0.412) Conclusion: As the pituitary adenoma volume increased, the increase in Beclin 1 expression level was found to be statistically significant and in non-functional pituitary adenomas compared to functional ones, the increase in Beclin 1 expression level was found to be statistically significant. There was no statistically significant difference in pituitary adenoma Ki-67 proliferation index, Knops and Hardy-Wilson radiological classification, primary-recurrence tumor status and Beclin 1 expression level. Keywords: Pituitary adenoma, Beclin 1, Knops and Hardy-Wilson radiological classification, Ki-67