Expression of vascular endothelial growth factor in growth hormone-secreting pituitary adenomas: special reference to the octreotide treatment

Abstract

We conclude that octreotide may inhibit the angiogenesis through down-regulation of VEGF.

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“…A low AIP score was found in large somatotropinomas [33]. No correlation of VEGF expression with tumour size was stated [29,31], which our study confirms.…”

“…In agreement with Kurosaki et al [31], we found no difference in VEGF expression between invasive and non-invasive tumours, as opposed to the suggested VEGF LI above 25% as a cut-off value for invasive somatotropinomas [36]. Higher VEGF expression was seen in invasive non-functioning giant adenomas and tumours with extrasellar growth [25,29], in contrast to low VEGF expression in patients, 70% of whom achieved remission [35].…”

“…Results concerning TOPO 2A expression are generally inconclusive: Vidal et al [11] found negative correlation between TOPO 2A expression and patient age and no correlation with patient gender, while elsewhere TOPO 2A expression did not depend on patient age [13,14]. Age and gender and adenoma type did not affect AIP [18] and VEGF expression [31].…”

“…On the other hand, in a RT-PCR study of different subtypes of pituitary adenomas, somatotropinomas showed lowest VEGF expression [29,30]. In IHC, expression of VEGF was decreased in somatotropinomas, against normal tissue [31].…”

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“…Additionally, experimental studies have shown that octreotide has antiangiogenic e f f e c t s , b y d o w n r e g u l a t i o n o f v a s c u l a r www.intechopen.com endothelial growth factor (VEGF). 8 In fact, a study reported endoscopic resolution of angiodysplastic lesions after treatment with octreotide, albeit the effect was not quantified. 9 Interestingly, a more recent study showed that a 3-month-treatment of long-acting release (LAR) octreotide 20 mg once a month in cirrhotic patients decreased significantly both the hepatic venous pressure gradient and VEGF in hepatic venous blood.…”