Objective: Klotho is a lifespan-influencing gene expressed mainly in the kidneys. Soluble a-Klotho (aKL) is released into the circulation. In this study, we present baseline aKL serum levels of patients with acromegaly compared with controls with other pituitary adenomas and assess changes following transsphenoidal surgery. Design: Prospective controlled study. Methods: We measured soluble aKL (sandwich ELISA) and IGF1 (RIA) in sera of 14 patients (eight females and six males) with active acromegaly and in 22 control patients (13 females and nine males) operated for non-GH-producing pituitary adenomas. Immunohistochemical staining for Klotho was performed in resected adenomas and in normal pituitary tissue samples. Results: Soluble aKL was high in the acromegaly group preoperatively (median 4217 pg/ml, interquartile range (IQR) 1812-6623 pg/ml) and declined after surgery during early follow-up (2-6 days; median 645 pg/ml, IQR 550-1303 pg/ml) (P!0.001) and during late follow-up (2-3 months post-operatively; median 902 pg/ml, IQR 497-1340 pg/ml; P!0.001). In controls, preoperative soluble aKL was significantly lower than in acromegalics, 532 pg/ml (400-677 pg/ml; P!0.001). Following surgery, soluble aKL remained low during early and late follow-up -changes over time within the control group were not statistically significant. These results were independent of age, sex and kidney function. Klotho staining was equal or slightly decreased in GH-positive adenomas compared with controls. Conclusion: High soluble aKL serum levels were specific to GH-producing adenomas and decreased rapidly following adenoma removal. Thus, soluble aKL appears to be a new specific and sensitive biomarker reflecting disease activity in acromegaly. Similar Klotho staining patterns in controls and acromegalics suggest that the rise in serum aKL is caused by systemic actions of pituitary GH rather than due to increased expression of Klotho by the pituitary (adenoma).

No abstract

Integrins αvβ3 and αvβ5 regulate angiogenesis and invasiveness in cancer, potentially by modulating activation of the transforming growth factor (TGF)-β pathway. The randomized phase III CENTRIC and phase II CORE trials explored the integrin inhibitor cilengitide in patients with newly diagnosed glioblastoma with versus without O6-methylguanine DNA methyltransferase (MGMT) promoter methylation. These trials failed to meet their primary endpoints.Immunohistochemistry was used to assess the levels of the target integrins of cilengitide, αvβ3 and αvβ5 integrins, of αvβ8 and of their putative target, phosphorylation of SMAD2, in tumor tissues from CENTRIC (n=274) and CORE (n=224).αvβ3 and αvβ5 expression correlated well in tumor and endothelial cells, but showed little association with αvβ8 or pSMAD2 levels. In CENTRIC, there was no interaction between the biomarkers and treatment for prediction of outcome. In CORE, higher αvβ3 levels in tumor cells were associated with improved progression-free survival by central review and with improved overall survival in patients treated with cilengitide.Integrins αvβ3, αvβ5 and αvβ8 are differentially expressed in glioblastoma. Integrin levels do not correlate with the activation level of the canonical TGF-β pathway. αvβ3 integrin expression may predict benefit from integrin inhibition in patients with glioblastoma lacking MGMT promoter methylation.

Glioblastoma is the most common and aggressive form of intrinsic brain tumor. Transforming growth factor (TGF)-represents a central mediator of the malignant phenotype of these tumors by promoting invasiveness and angiogenesis, maintaining tumor cell stemness and inducing profound immunosuppression. Integrins, which are highly expressed in glioma cells, interact with the TGF-pathway. Furthermore, a link has been described between activity of the transcription factor aryl hydrocarbon receptor (AhR) and TGF-expression. Here we demonstrate that integrin inhibition, using v, 3 or 5 neutralizing antibodies, RNA interference-mediated integrin gene silencing or pharmacological inhibition by the cyclic RGD peptide EMD 121974 (cilengitide) or the non-peptidic molecule GLPG0187, inhibits AhR activity. These effects are independent of cell detachment or cell density. While AhR mRNA expression was not affected by integrin inhibition, AhR total and nuclear protein levels were reduced, suggesting that integrin inhibition-mediated regulation of AhR may occur at a post-transcriptional level. AhR-null astrocytes, AhR-null hepatocytes or glioblastoma cells with a transiently silenced AhR gene showed reduced sensitivity to integrin inhibition-mediated alterations in TGF-signaling, indicating that AhR mediates integrin control of the TGF-pathway. Accordingly, there was a significant correlation of v integrin levels with nuclear AhR and pSmad2 levels as determined by immunohistochemistry in human glioblastoma in vivo. In summary, this study identifies a signaling network comprising integrins, AhR and TGF-and validates integrin inhibition as a promising strategy not only to inhibit angiogenesis, but also to block AhR-and TGF--controlled features of malignancy in human glioblastoma. Here we demonstrate that integrin inhibition, using αv, β3 or β5 neutralizing antibodies, RNA interference-mediated integrin gene silencing or pharmacological inhibition by the cyclic RGD peptide EMD 121974 (cilengitide) or the non-peptidic molecule GLPG0187, inhibits AhR activity.These effects are independent of cell detachment or cell density. While AhR mRNA expression was not affected by integrin inhibition, AhR total and nuclear protein levels were reduced, suggesting that integrin inhibition-mediated regulation of AhR may occur at a posttranscriptional level. AhR-null astrocytes, AhR-null hepatocytes, or glioblastoma cells with a transiently silenced AhR gene showed reduced sensitivity to integrin inhibition-mediated alterations in TGF-β signaling indicating that AhR mediates integrin control of the TGF-β pathway. Accordingly, there was a significant correlation of αv integrin levels with nuclear AhR and pSmad2 levels as determined by immunohistochemistry in human glioblastoma in vivo.In summary, this study identifies a signaling network comprising integrins, AhR and TGF-β and validates integrin inhibition as a promising strategy not only to inhibit angiogenesis, but also to block AhR-and TGF--controlled features of malignancy in human glio...