The Warburg Effect Is Genetically Determined in Inherited Pheochromocytomas

The Warburg effect describes how cancer cells down-regulate their aerobic respiration and preferentially use glycolysis to generate energy. To evaluate the link between hypoxia and Warburg effect, we studied mitochondrial electron transport, angiogenesis and glycolysis in pheochromocytomas induced by germ-line mutations in VHL, RET, NF1 and SDH genes. SDH and VHL gene mutations have been shown to lead to the activation of hypoxic response, even in normoxic conditions, a process now referred to as pseudohypoxia. We observed a decrease in electron transport protein expression and activity, associated with increased angiogenesis in SDH- and VHL-related, pseudohypoxic tumors, while stimulation of glycolysis was solely observed in VHL tumors. Moreover, microarray analyses revealed that expression of genes involved in these metabolic pathways is an efficient tool for classification of pheochromocytomas in accordance with the predisposition gene mutated. Our data suggest an unexpected association between pseudohypoxia and loss of p53, which leads to a distinct Warburg effect in VHL-related pheochromocytomas

Major prognostic role of Ki67 in localized adrenocortical carcinoma after complete resection

Background: Recurrence of adrenocortical carcinoma (ACC) even after complete (R0) resection occurs frequently. Objective: The aim of this study was to identify markers with prognostic value for patients in this clinical setting. Design, Setting, and Participants: From the German ACC registry, 319 patients with the European Network for the Study of Adrenal Tumors stage I-III were identified. As an independent validation cohort, 250 patients from three European countries were included. Outcome Measurements and Statistical Analysis: Clinical, histological, and immunohistochemical markers were correlated with recurrence-free (RFS) and overall survival (OS). Results: Although univariable analysis within the German cohort suggested several factors with potential prognostic power, upon multivariable adjustment only a few including age, tumor size, venous tumor thrombus (VTT), and the proliferation marker Ki67 retained significance. Among these, Ki67 provided the single best prognostic value for RFS (hazard ratio [HR] for recurrence, 1.042 per 1% increase; P <.0001) and OS (HR for death, 1.051; P <.0001) which was confirmed in the validation cohort. Accordingly, clinical outcome differed significantly between patients with Ki6

Recurrence-Free Survival Analysis in Locally Advanced Pheochromocytoma: First Appraisal

International audienceAbstract Context The behavior of locally advanced pheochromocytoma (LAP) remains unknown. Objective We characterized the population with LAP and recurrence-free survival (RFS). Methods This retrospective multicentric study was run within the ENDOCAN-COMETE network and French Group of Endocrine Tumors (GTE) from 2003 to 2018, including patients from 11 French referral centers with LAP as defined by capsular invasion, vascular invasion, adipose tissue invasion, and/or positive locoregional lymph nodes at diagnosis without evidence of distant metastasis. The main outcome measure was recurrence, defined as tumor reappearance, including local site and/or distant metastasis. The primary endpoint was RFS analysis; secondary endpoints were characterization, overall survival (OS), and prognostic factors of recurrence. Results Among 950 patients, 90 (9%) exhibited LAP criteria and 55 met inclusion criteria (median age, 53 years; 61% males; 14% with germline mutation; 84% with catecholamine excess). LAP was defined by 31 (56%) capsular invasions, 27 (49%) fat invasions, 6 (11%) positive lymph nodes, and 22 (40%) vascular invasions. After median follow-up of 54 months (range, 6-180), 12 patients (22%) had recurrences and 3 (5%) died of metastatic disease. Median RFS was 115 months (range, 6-168). Recurrences were local in 2 patients, distant in 2, and both local and distant in 8 patients. Median OS of patients was not reached. Size above 6.5 cm (P = 0.019) and Ki-67 &gt; 2% (P = 0.028) were identified as independent significant prognostic factors in multivariate analysis. Conclusion LAP represents 9% of pheochromocytoma’s population and has a metastatic behavior. This study paves the way for future pathological TNM classification

Microarray analysis of oxidative phosphorylation in hereditary PH/PGL.

<p>(A) Unsupervised hierarchical clustering analysis of the 68 samples according to the expression of 200 genes. Expression profiles are shown as a heat map indicating high (red) and low (blue) expression according to a log2-transformed scale. The higher bipartition allows to distinguish VHL (white) and SDH (grey) patients from RET and NF1 (black) patients. (B) Principal component analysis of the 68 samples according to the expression of 200 genes. Three groups are focused on, corresponding to the SDH (red), VHL (green) and RET/NF1 (blue) patients. PC1: principal component; PC2: principal component 2; PC3: principal component 3. (C) Mean values for genes expression between SDH, VHL, RET and NF1 tumors. Data are means±SEM, represented as relative to NF1 expression values. **p<0.01, ***p<0.001.</p

Decreased oxidative phosphorylation in SDH and VHL-related PH/PGL.

<p>(A) The abundance of proteins of mitochondrial complexes I (20 kDa subunit), II (SDHB and SDHA), III (Core 2) and IV (Cox II) is lower in PH/PGL from SDH and most VHL than from RET and tumor tissues. (B) SDHB immunohistochemistry performed on the adrenal adjacent to a RET-related PH and in RET, VHL and SDHD-mutated PH reveals a strong labeling in the adrenal compared to tumor cells (asterisks). In VHL PH/PGL tumor, expression of SDHB was reduced when compared to RET-related PH while it is absent in SDHD-related tumor. Note that vascular immunostaining was present in all samples (arrows). Calibration bar: 50 µm. (C) Individual values of SCCR activity reveal that low complex II+III enzymatic activity is associated with low protein abundance. (D–F) Mean values for mitochondrial complexes II+III, III and IV reveal a generalized decrease in respiration in SDH and VHL PH/PGL. Data are means±SEM. **p<0.01, ***p<0.001.</p

Angiogenesis in SDH and VHL-related PH/PGL.

<p>(A) CD34 immunohistochemistry was performed to evaluate angiogenesis in all samples. Diaminobenzidin was used as a chromogen for detection (brown labeling). Calibration bar: 200 µm. (B) Quantification of vascular density showing an increased number of blood vessels in SDH, and VHL tissues. Data are means±SEM. *p<0.05, **p<0.01, ***p<0.001. (C) Correlation between vascular density and SCCR enzymatic values for individual patients.</p

Microarray analysis of glycolysis in hereditary PH/PGL.

<p>(A) Unsupervised hierarchical clustering analysis of the 68 samples according to the expression of 38 genes. Expression profiles are shown as a heat map indicating high (red) and low (blue) expression according to a log2-transformed scale. The different mutations are localized in three distinct clusters: SDH (grey), VHL (white) and RET/NF1 (black). (B) Mean values for genes expression between SDH, VHL, RET and NF1 tumors. Data are means±SEM, represented as relative to NF1 expression values. **p<0.01, ***p<0.001.</p

Pseudohypoxia in SDH and VHL-related PH/PGL.

<p>(A) HIF-1α and HIF-2α immunohistochemistry were performed to evaluate activation of the hypoxic pathway in all samples. Histogreen was used as a chromogen for detection (blue labeling). Calibration bar: 100 µm. Microarray evaluation of HIF-1α (B) and HIF-2α (C) expression between SDH, VHL, RET and NF1 tumors. Data are means±SEM. ***p<0.001.</p