Activation of the AMP-related kinase (AMPK) induces renal vasodilatation and downregulates Nox-derived reactive oxygen species (ROS) generation.

AMP-activated protein kinase (AMPK) is a cellular energy sensor activated during energy stress to stimulate ATP production pathways and restore homeostasis. AMPK is widely expressed in the kidney and involved in mitochondrial protection and biogenesis upon acute renal ischemia, AMPK activity being blunted in metabolic disease-associated kidney disease. Since little is known about AMPK in the regulation of renal blood flow, the present study aimed to assess the role of AMPK in renal vascular function. Functional responses to the selective AMPK activator A769662 were assessed in intrarenal small arteries isolated from the kidney of renal tumour patients and Wistar rats and mounted in microvascular myographs to perform simultaneous measurements of intracellular calcium [Ca2+]i and tension. Superoxide (O2.-) and hydrogen peroxide (H2O2) production were measured by chemiluminescence and fluorescence and protein expression by Western blot. Activation of AMPK with A769662 increased AMPKα phosphorylation at Thr-172 and induced potent relaxations compared to AICAR in isolated human and rat intrarenal arteries, through both endothelium-dependent mechanisms involving nitric oxide (NO) and intermediate-conductance calcium-activated potassium (IKCa) channels, as well as activation of ATP-sensitive (KATP) channels and sarcoplasmic reticulum Ca2+-ATPase (SERCA) in vascular smooth muscle (VSM). Furthermore, AMPK activator reduced NADPH oxidase 4 (Nox4) and Nox2-derived reactive oxygen species (ROS) production. These results demonstrate that A769662 has potent vasodilator and antioxidant effects in intrarenal arteries. The benefits of AMPK activation in rat kidney are reproduced in human arteries and therefore vascular AMPK activation might be a therapeutic target in the treatment of metabolic disease-associated kidney injury.

Hydrogen peroxide derived from NADPH oxidase 4- and 2 contributes to the endothelium-dependent vasodilatation of intrarenal arteries.

The role of NADPH oxidase (Nox)-derived reactive oxygen species in kidney vascular function has extensively been investigated in the harmful context of oxidative stress in diabetes and obesity-associated kidney disease. Since hydrogen peroxide (H2O2) has recently been involved in the non-nitric oxide (NO) non-prostanoid relaxations of intrarenal arteries, the present study was sought to investigate whether NADPH oxidases may be functional sources of vasodilator H2O2 in the kidney and to assess their role in the endothelium-dependent relaxations of human and rat intrarenal arteries. Renal interlobar arteries isolated from the kidney of renal tumor patients who underwent nephrectomy, and from the kidney of Wistar rats, were mounted in microvascular myographs to assess function. Superoxide (O2.-) and H2O2 production was measured by chemiluminescence and Amplex Red fluorescence, and Nox2 and Nox4 enzymes were detected by Western blotting and by double inmunolabeling along with eNOS. Nox2 and Nox4 proteins were expressed in the endothelium of renal arterioles and glomeruli co-localized with eNOS, levels of expression of both enzymes being higher in the cortex than in isolated arteries. Pharmacological inhibition of Nox with apocynin and of CYP 2C epoxygenases with sulfaphenazol, but not of the NO synthase (NOS), reduced renal NADPH-stimulated O2.- and H2O2 production. Under conditions of cyclooxygenase and NOS blockade, acetylcholine induced endothelium-dependent relaxations that were blunted by the non-selective Nox inhibitor apocynin and by the Nox2 or the Nox1/4 inhibitors gp91ds-tat and GKT136901, respectively. Acetylcholine stimulated H2O2 production that was reduced by gp91ds-tat and by GKT136901. These results suggest the specific involvement of Nox4 and Nox2 subunits as physiologically relevant endothelial sources of H2O2 generation that contribute to the endothelium-dependent vasodilatation of renal arteries and therefore have a protective role in kidney vasculature.

Cytologic features of pleomorphic xanthoastrocytoma, WHO grade II. A comparative study with glioblastoma.

Pleomorphic xanthoastrocytoma (PXA) is a WHO grade II astrocytic tumor of children and young adults. It is characterized by pleomorphic, atypical astrocytes. Atypia is so remarkable, that PXA can be easily misdiagnosed as malignant glioma. If confused with a high-grade glioma the neurosurgeon may not proceed with a complete resection. Therefore, a specific recognition during intraoperative consultation is particularly important. We describe four cases of PXA evaluated during intraoperative procedures. Findings were compared with those of 22 glioblastomas. PXA smears were moderately cellular and showed a variable population of pleomorphic cells and fibrillary fragments with vessels. Tumoral cells were of intermediate size with a less frequent population of large, atypical cells. Some showed bi/trinucleation with bizarre nuclei. In two cases, tumoral cells with microvacuolization resembling xanthic astrocytes were present. No necrosis, mitotic activity, phagocytic macrophages or apoptotic fragments were seen. Smears from glioblastoma were more cellular than those of PXA with numerous neoplastic cells, branching vessels and myxoid substance. Cellular atypia was evident and mitoses were seen in all cases. Most cases showed an abundant population of accompanying macrophages and cellular debris. Differences between PXA and glioblastoma were related to cell turnover rather than cytomorphologic features. Glioblastoma shows features of high cellular replication showing a dirty background with necrosis and phagocytic macrophages as well as mitotic figures and apoptosis. On the other hand, smears from PXA have a clean background with no necrosis, cellular fragments or relevant mitotic activity. Diagn. Cytopathol. 2017;45:339-344. © 2016 Wiley Periodicals, Inc.

Differential transplantability of human endothelial cells in colorectal cancer and renal cell carcinoma primary xenografts.

In vivo models of human tumor vasculature are essential for the study of tumor angiogenesis and validation of therapeutic targets. To date, however, few standardized animal models of human tumor angiogenesis have been characterized. It was recently shown that human renal cell and prostate carcinoma primary xenografts, established from biopsy specimens, contained vessels lined mainly by human endothelial cells 1 month after implantation in immunodeficient mice. We selected colorectal cancer (CRC) as a primary xenograft model and studied the response of the vascular compartment to the new microenvironment during the same lapse of time. Immunohistochemical analysis of the origin of endothelial cells demonstrated that, in contrast to the mentioned study, human endothelial cells were rapidly substituted by their murine counterparts (nearly 50% by day 10 after implantation). Apoptotic human endothelial cells could not be detected 10 days after implantation, suggesting that apoptosis is not the mechanism underlying their replacement. Interestingly, host endothelial cells were found to colocalize with human laminin, suggesting a colonization of human vascular basement membranes after human endothelial cell disappearance. To rule out that the differences observed between the fate of human vasculature in the CRC model and those previously reported were because of methodological aspects, we established renal cell carcinoma (RCC) primary xenografts using the same protocol. In clear contrast with CRC xenografts, vasculature within RCC xenografts was mostly of human origin 35 days after implantation. These results support the notion of angiogenic heterogeneity in malignant neoplasms. Elucidation of the molecular mechanisms that determine persistence or disappearance of human endothelial cells in different tumor contexts can help to shed light on the intimate regulation of the angiogenic process.

Immunohistochemistry and microsatellite instability testing for selecting MLH1, MSH2 and MSH6 mutation carriers in hereditary non-polyposis colorectal cancer.

Hereditary non-polyposis colorectal cancer (HNPCC) represents 1-3% of all colorectal cancers. HNPCC is caused by a constitutional defect in a mismatch repair (MMR) gene, most commonly affecting the genes MLH1, MSH2 and MSH6. The MMR defect results in an increased cancer risk, with the greatest lifetime risk for colorectal cancer and other cancers associated to HNPCC. The HNPCC-associated tumor phenotype is generally characterized by microsatellite instability (MSI) and immunohistochemical loss of expression of the affected MMR protein. The aim of this study was to determine the sensitivity of IHC for MLH1, MSH2 and MSH6, and MSI analysis in tumors from known MMR gene mutation carriers. Fifty-eight paired normal and tumor samples from HNPCC families enrolled in our high-risk colorectal cancer registry were studied for the presence of germline mutations in MLH1, MSH2 and MSH6 by DGGE and direct sequencing. MSI analysis and immunostaining for MLH1, MSH2 and MSH6 were evaluated. Of the 28 patients with a real pathogenic mutation, loss of immunohistochemical expression for at least 1 of these MMR proteins was found, and all except 1 have MSI-H. Sensitivity by MSI analysis was 96%. IHC analysis had a sensitivity of 100% in detecting MMR deficiency in carriers of a pathogenic MMR mutation, and can be used to predict which gene is expected to harbor the mutation for MLH1, MSH2 and MSH6. This study suggests that both analyses are useful for selecting high-risk patients because most MLH1, MSH2 and MSH6 gene carriers will be detected by this 2-step approach. This practical method should have immediate application in the clinical work of patients with inherited colorectal cancer syndromes.

The topoisomerase IIalpha expression correlates with survival in patients with advanced Hodgkin's lymphoma.

PURPOSE: Topoisomerase (Topo) II isoenzymes are the targets for drugs, such as epidophyllotoxins and doxorubicin. The aim of this study was to determine whether the expression of Topo IIalpha and Ki67 in advanced Hodgkin's disease (HD) played a role as a prognostic factor or predictor of response to treatment. EXPERIMENTAL DESIGN: Forty-two patients who were homogeneously treated and had a long-term follow-up were selected for the study. Immunohistochemistry of paraffin-embedded tissue sections was performed. The effect of patient and tumor characteristics on failure-free survival (FFS) and overall survival were evaluated in a univariate analysis using the Cox proportional hazards model. The Cox model was also implemented in a multivariate analysis using stepwise selection. RESULTS: Positive nuclear staining for Topo IIalpha in Reed-Stemberg or Reed-Stemberg variant cells was seen in 90% of HD cases, and coexpression of Ki67 and Topo IIalpha in 79%. No significant difference in the percentage of Topo IIalpha-positive cells was detected among histological HD subtypes. In the univariate analysis for FFS, the male gender, high lactate dehydrogenase, and Topo IIalpha < 30% were associated with more relapses. In the multivariate analysis for FFS, only Topo IIalpha < 30% was statistically associated with shorter FFS, with relative risk of 3 (95% confidence interval, 1.26-7.15; P = 0.013). In uni- and multivariate analyses for overall survival, only Topo IIalpha was associated with shorter survival. CONCLUSIONS: Topo IIalpha expression could be useful in advanced HD to identify patients with a higher risk of relapse and lesser overall survival. It is of potential utility in the design of specific treatments.