Differential expression levels of ß-catenin are associated with invasive behavior of both functional and non-functional pituitary neuroendocrine tumor (PitNET).

BACKGROUND: Although research continues to elucidate the molecular mechanism underlying pituitary tumor pathogenesis, limited information is available on the potential role and expression profile of ß-catenin in functional and non-functional pituitary neuroendocrine tumors (PitNETs). METHODS AND RESULTS: In the current study, 104 pituitary samples (tumors and cadaveric healthy pituitary tissues) were included and the gene and protein expression levels of ß-catenin were assessed by Real-Time PCR and immunohistochemistry, respectively. The correlation between expression level of ß-catenin and tumor invasive feature and size as well as patient age, gender, and hormonal level was measured. The data showed that PitNET samples expressed higher levels of the ß-catenin gene and protein compared to healthy pituitary tissues. Although there was no difference in ß-catenin expression level between non-functioning (NF-PitNETs) and growth hormone-producing tumors (GH-PitNETs), both tumor types showed significantly elevated ß-catenin levels compared to healthy pituitary tissues. The high level of ß-catenin in the invasive functional and non-functional tumors is indicative of the association of ß-catenin with PitNETs invasion. The expression pattern of the ß-catenin gene and protein was consistently and significantly associated with these tumor types. The correlation between ß-catenin and insulin-like growth factor 1 (IGF-1) in GH-PitNETs indicates the potential relevance of ß-catenin and IGF-1 for GH-PitNETs. CONCLUSIONS: The simultaneous increase in the expression of ß-catenin gene and protein level in PitNET tissues and their relationship to the tumor severity indicates the possible contributing role of ß-catenin and its underlying signaling mediators in PitNET pathogenesis.

Evaluating the expression pattern of the opioid receptor in pituitary neuroendocrine tumors (PitNET) and the role of morphine and naloxone in the regulation of pituitary cell line growth and apoptosis.

PURPOSE: The expression pattern of the opioid receptor (MOR) in pituitary neuroendocrine tumors (PitNET) and the possible effect of morphine and naloxone on GH3 cell growth and apoptosis were evaluated. METHODS: The 114 pituitary tissues including non-functioning, GH-producing and ACTH-producing PitNET and healthy cadaver pituitary tissues were included. The expression level of the MOR gene and protein was assessed using real-time PCR and Western blot. The association with patient demographic characteristics was assessed. Morphine and naloxone were applied to assess their possible pharmacological role in GH3 pituitary adenoma cell death. The cytotoxic effect, the apoptosis rate, the cell cycle distribution, the content of reactive oxygen species and the caspase 3 activity were measured. RESULTS: MOR gene levels increased significantly in pituitary neuroendocrine tumors (PitNET) compared to the healthy pituitary samples. The increased level of MOR gene expression was prominent in invasive functional and non-functional pituitary tumors. A consistent expression pattern was demonstrated for MOR protein levels in PitNET samples. A dose- and time-dependent reduction in the rate of GH3 pituitary cells was observed after morphine treatment with an IC50 of 483 µM after 24 h of incubation. Morphine induced early apoptosis, accumulation of cells in sub-G1 phase, increase in cellular ROS levels and caspase-3 activity. The observed effects of morphine were reversed after MOR blockade using 10 and 25 µM naloxone. CONCLUSION: The possible contributing role of the MOR in pituitary tumor cell growth and the putative pharmaceutical effect of morphine in pituitary neuroendocrine tumor cell death (PitNET) is illustrated.

Cyclooxygenase enzyme and PGE2 expression in patients with functional and non-functional pituitary adenomas.

BACKGROUND: Pituitary adenomas as multifactorial intracranial neoplasms impose a massive burden of morbidity on patients and characterizing the molecular mechanism underlying their pathogenesis has received considerable attention. Despite the appealing role of cyclooxygenase enzymes and their bioactive lipid products in cancer pathogenesis, their relevance to pituitary adenoma pathogenesis is debated and yet to be determined. Thus, the current study perused this relevance. METHODS: The expression level of the isoforms of cyclooxygenase (COX-1 and COX-2) was evaluated in hormone-secreting and in-active pituitary adenoma tumors and normal pituitary tissues through Real-Time PCR. The level of PGE2, as the main product of enzymes, was assessed using enzyme immunoassay kits in patients and healthy subjects. RESULTS: The results of the current study demonstrated that COX-1 and COX-2 expression levels were increased in pituitary tumors including non-functional pituitary adenoma (NFPA), acromegaly, Cushing's disease and prolactinoma compared with normal pituitary tissues. A significant expression level of COX-2 was observed in NFPA compared with the other pituitary tumors. Furthermore, the COX-2 expression level was significantly increased in macroadenoma and invasive tumors. The level of PGE2 was consistent with COX enzymes enhanced in pituitary adenoma tumors compared with healthy pituitary tissue. A significant elevation in the PGE2 level was detected in NFPA compared with hormone-secreting pituitary tumors. Additionally, the PGE2 level was increased in macroadenoma compared with microadenoma and in invasive compared with non-invasive pituitary tumors. The diagnostic values of cyclooxygenase isoforms and PGE2 were considerable between patients and healthy groups; however, COX-2 revealed more value in distinguishing endocrinologically active and non-active pituitary tumors. CONCLUSIONS: Data from the current study provides expression patterns of COX-1, COX-2 and PGE2 in prevalent pituitary tumors and their association with patients' clinical features which may open up new molecular targets for early diagnosis/follow up of pituitary tumor growth.