Expression of voltage gated potassium channel ether a go-go in pituitary adenomas of patients with acromegaly: A preliminary study

OBJECTIVE: To determine immunohistochemical expression of Eag1 in pituitary adenomas of patients with acromegaly and to assess the correlation between Eag1 expression with cavernous sinus invasion, tumoral Ki-67 labeling index (LI), age and gender of the patients. METHODS: The paraffin embedded pituitary adenoma tissue sections of 28 patients with acromegaly who were diagnosed as monohormonal growth hormone (GH) secreting adenomas were immunostained for Eag1 using the avidin-biotin-peroxidase complex method. Eag1 immunoreactivity was scored according to the extensity of the cytoplasm and cell membrane immunoreactivity for Eag1 (score 1 = 50% of the adenoma cells showed immunoreactivity for Eag1, respectively). RESULTS: Overall, GH secreting pituitary adenomas displayed diverse levels of Eag1 immunoreactivity, however, 64% of the adenomas displayed a strong Eag1 immunoreactivity (score 3 and 4). Five of the tumors displayed Eag1 immunoreactivity score 1, 5 displayed score 2, 10 displayed score 3 and 8 displayed score 4, respectively. No correlation was found between Eag1 immunoreactivity with cavernous sinus invasion, Ki-67 LI, age and gender of the patients. CONCLUSIONS: Our results suggest Eag1 is strongly expressed in the majority of GH secreting pituitary adenomas. However, we could not find any correlation between immunoreactivity of Eag1 with cavernous sinus invasion, Ki-67 LI, age and gender of the patients. Further studies with larger sample sizes are required to demonstrate the role of Eag1 on tumorigenesis, angiogenesis, invasion and response to the treatment in GH secreting pituitary adenomas