Sharma, Soniya

Pituitary tumor transforming gene (PTTG) plays a role in many cellular processes. PTTG overexpression is seen in several tumor types and correlates with survival time/recurrence. We evaluated PTTG expression in various types of brain tumors (n=94). Immunohistochemistry was performed using a monoclonal PTTG antibody (DCS‐280, Abcam;Cambridge, MA) and the streptavidin‐biotin‐peroxidase complex method. The intensity of PTTG immunoreactivity was evaluated semi‐quantitatively on a 0‐4 scale. PTTG expression was evident in most tumor cells and was predominantly nuclear. In glial tumors, PTTG immunoreactivity was higher in glioblastomas (IV), anaplastic oligoastrocytomas (III), anaplastic oligodendrogliomas (III), oligoastrocytomas (II), oligodendrogliomas (II), and pilocytic astrocytomas (I) (range: 3.1–3.5), whereas notably lower PTTG was seen in myxopapillary ependymomas (I) and ependymomas (II) (1.5 & 1.6). In non‐glial tumors, hemangiopericytomas and schwannomas had higher PTTG score (3.4), than meningiomas (2.3). Thus, it appears that PTTG expression is not associated with tumor grade, but rather with tumor type, the most striking difference being between ependymomas and other glial tumors. PTTG may be a valuable therapy target in some brain tumors. Acknowledgments Authors thank the Jarislowsky Foundation and the Lloyd‐Carr‐Harris Foundation for their generous support.

Ghrelin, a 28 amino acid‐containing orexigenic peptide, is an endogenous ligand of the GH secretagogue receptor. It was extracted from the rat stomach, but is present in other organs. The aim of this work was to localize ghrelin by immunohistochemistry in autopsy‐derived non‐tumorous human pituitaries. Immunohistochemistry was performed using the streptavidin‐biotin‐peroxidase complex method and the results were analyzed independently by 3 of the authors. Double Immunostaining was also undertaken to determine which cell type was expressing both the adenohypophysial hormone and ghrelin. Results showed that ghrelin can be localized in the adenohypophysis. It's immunoexpression being cytoplasmic, weak to moderate, and present in only a subset of cells. The neurohypophysis is immunonegative. Double immunostaining showed that ghrelin is co‐localized with GH, ACTH and LH and is present to 51–90% of such cells. PRL, TSH and FSH cells are consistently non‐reactive. The role of ghrelin in adenohypophysial endocrine activity is not clear. It may well be that ghrelin exerts an autocrine‐paracrine effect and can modulate hormone synthesis and release.

Angiogenesis is a crucial event in tumor growth, invasion and development of metastasis. Endoglin (CD‐105), a disulfide‐linked homodimeric cell membrane glycoprotein of 180 kDa, located on chromosome 9q and binds to several components of the TGF beta family. In contrast to other endothelial cell markers, endoglin can be demonstrated only in proliferating endothelial cells. We investigated endoglin immunoexpression in various surgically removed human pituitary tumor types and compared the results with CD‐34 immunoexpression. For immunohistochemistry, the streptavidin‐biotin‐peroxidase complex method was used and the number of vessels were counted in 10 low power fields. Results show that endoglin immunostains fewer vessels than CD‐34 in every pituitary adenoma type. The number of endoglin immunopositive vessels is highest in untreated prolactinomas and subtype 3 silent pituitary adenomas and lowest in subtype 1 silent corticotroph adenomas and GH adenomas exposed to somatostatin analogs and prolactinomas exposed to dopamine agonists. Our findings are consistent with the view that endoglin is upregulated in proliferating endothelial cells and its expression can be used as an indicator of vascular neoformation in pituitary tumors. The low levels of endoglin expression in pituitary tumors exposed to somatostatin or dopamine agonists suggests that these therapeutic drugs can inhibit angiogenesis.

Objective MGMT expression in brain and pituitary tumors has been correlated with temozolomide treatment. Few medical therapies are available in patients with Nelson Syndrome. The aim of the present study was to assess immunohistochemical expression of MGMT in ACTH‐secreting pituitary adenomas in patients with Nelson Syndrome. Methods Our material consisted of specimens from ACTH‐secreting pituitary adenomas from patients with Nelson Syndrome. Immunohistochemical staining for MGMT was performed using the streptavidin‐biotin‐peroxidase complex method. MGMT immunoreactivity was assessed microscopically and recorded as an estimated percentage of nuclear MGMT immunopositivity. (0=none, 1=<10%, 3=<50%, 4=>50%) Results Male:Female ratio was 3:5, with average patient age being 62 (range 57–66). Five of the eight specimens (65%) exhibited no MGMT immunoreactivity, with two out of eight cases (25%) showing slight MGMT immunopositivity and one out of eight cases (12%) demonstrating moderate MGMT immunopositivity (<25%). Conclusions Temozolomide therapy may be useful in patients with Nelson Syndrome. Absent or low MGMT staining in brain and other neoplasms has been shown to correlate with successful treatment with temozolomide, and recent reports assessing aggressive pituitary adenomas suggest similar outcome.