BackgroundFKBP51 is a co-chaperone with isomerase activity, abundantly expressed in glioma. We previously identified a spliced isoform (FKBP51s) and highlighted a role for this protein in the upregulation of Programmed Death Ligand 1 (PD-L1) expression in melanoma. Because gliomas can express PD-L1 causing a defective host anti-tumoral immunity, we investigated whether FKBP51s was expressed in glioma and played a role in PD-L1 regulation in this tumour.MethodsWe used D54 and U251 glioblastoma cell lines that constitutively expressed PD-L1. FKBP51s was measured by immunoblot, flow cytometry and microscopy. In patient tumours, IHC and qPCR were used to measure protein and mRNA levels respectively. FKBP51s depletion was achieved by siRNAs, and its enzymatic function was inhibited using selective inhibitors (SAFit). We investigated protein maturation using N-glycosidase and cell fractionation approaches.ResultsFKBP51s was expressed at high levels in glioma cells. Glycosylated-PD-L1 was increased and reduced by FKBP51s overexpression or silencing, respectively. Naïve PD-L1 was found in the endoplasmic reticulum (ER) of glioma cells complexed with FKBP51s, whereas the glycosylated form was measured in the Golgi apparatus. SAFit reduced PD-L1 levels (constitutively expressed and ionizing radiation-induced). SAFit reduced cell death of PBMC co-cultured with glioma.ConclusionsHere we addressed the mechanism of post-translational regulation of PD-L1 protein in glioma. FKBP51s upregulated PD-L1 expression on the plasma membrane by catalysing the protein folding required for subsequent glycosylation. Inhibition of FKBP51s isomerase activity by SAFit decreased PD-L1 levels. These findings suggest that FKBP51s is a potential target of immunomodulatory strategies for glioblastoma treatment.
Pretreatment with octreotide (OCT) in acromegaly has been reported to improve surgical outcome. The objective of this study was to analyze retrospectively the effects of a 3- to 6-month presurgical treatment with OCT in acromegalics focusing on electrocardiographic (ECG) records, blood pressure levels, glucose and lipid profile, tumor size and consistency, easy tumor removal at surgery, and morphological findings at pathology. Fifty-nine patients with acromegaly who were undergoing surgical treatment were studied randomly before surgery; 37 patients were untreated, and 22 were treated with OCT at doses ranging 150-600 micrograms/day for 3-6 months. At study entry, untreated and OCT-treated patients had similar circulating GH and insulin-like growth factor I (IGF-I), glucose, and cholesterol levels as well as prevalence of overt diabetes mellitus, hypertension, and ECG abnormalities. In untreated and OCT-treated patients, respectively, radiological imaging documented microadenoma in 0 and 1, intrasellar macroadenoma in 10 and 6, intra- and suprasellar macroadenoma in 18 and 11, invasive macroadenoma in 9 and 4 patients. Before surgery, serum GH and IGF-I levels significantly decreased in the 22 OCT-treated acromegalics, and in 5 of them, a significant shrinkage was documented. ECG abnormalities disappeared in 7 of 11 (63.6%) OCT-treated patients. In 3 of the 7 patients with diabetes mellitus, treatment with OCT together with low carbohydrate intake normalized blood glucose levels, whereas in 2 patients, insulin could be replaced by oral antidiabetics, and in 2 patients, the insulin dose was reduced. Presurgical blood glucose, total cholesterol and triglyceride levels, as well as systolic (145.2 +/- 3.4 vs. 132.9 +/- 2.5 mm Hg; P < 0.01) and diastolic (94.3 +/- 1.7 vs. 84.3 +/- 1.6 mm Hg; P < 0.001) blood pressure levels were significantly higher in untreated than in OCT-treated patients. Two weeks after surgery, circulating GH and IGF-I levels were normalized in 11 untreated (29.7%) and 12 OCT-treated (54.5%) patients (P < 0.005, by chi 2 test). Macroscopically, no difference was found between untreated and OCT-treated adenomas, whereas at pathology, a significant increases in cellular atypia (31.6% vs. 19.2%; P < 0.05) was found in OCT-treated adenomas. One patients in the untreated group died from cardiorespiratory arrest during the early postoperative period. Finally, the average duration of hospitalization after operation was longer in untreated than in OCT-treated patients (8.6 +/- 0.7 vs. 5.6 +/- 0.5 days). We conclude that a 3- to 6-month treatment with OCT before surgery for GH-secreting adenoma improved clinical conditions and surgical outcome and reduced the duration of hospitalization after operation.
Glioblastoma (GBM), the most malignant of the brain tumors, has been classified on the basis of molecular signature into four subtypes: classical, mesenchymal, proneural and neural, among which the mesenchymal and proneural subtypes have the shortest and longest survival, respectively. Here we show that the transcription factor PATZ1 gene is upregulated in gliomas compared to normal brain and, among GBMs, is particularly enriched in the proneural subtype and co-localize with stemness markers. Accordingly, in GBM-derived glioma-initiating stem cells (GSCs) PATZ1 is overexpressed compared to differentiated tumor cells and its expression significantly correlates with the characteristic stem cell capacity to grow as neurospheres in vitro. Interestingly, survival analysis demonstrated that PATZ1 lower levels informed poor prognosis in GBM and, specifically, in the proneural subgroup, suggesting it may serve a role as diagnostic and prognostic biomarker for intra-subtype heterogeneity of proneural GBM. We also show that PATZ1 suppresses the expression of the mesenchyme-inducer CXCR4, and that PATZ1 and CXCR4 are inversely correlated in GSC and proneural GBM. Overall these findings support a central role of PATZ1 in regulating malignancy of GBM.
The WHO classification is suitable to accurately reclassify tumors with an initial diagnosis referable to a NET and to separate these tumors in 3 well-distinct histo-prognostic categories with relevant clinical implications. Ki-67 score seems to be a better predictor of survival than the degree of differentiation.
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