The CDKN2A G500 Allele Is More Frequent in GBM Patients with No Defined Telomere Maintenance Mechanism Tumors and Is Associated with Poorer Survival

Prognostic markers for glioblastoma multiforme (GBM) are important for patient management. Recent advances have identified prognostic markers for GBMs that use telomerase or the alternative lengthening of telomeres (ALT) mechanism for telomere maintenance. Approximately 40% of GBMs have no defined telomere maintenance mechanism (NDTMM), with a mixed survival for affected individuals. This study examined genetic variants in the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene that encodes the p16INK4a and p14ARF tumor suppressors, and the isocitrate dehydrogenase 1 (IDH1) gene as potential markers of survival for 40 individuals with NDTMM GBMs (telomerase negative and ALT negative by standard assays), 50 individuals with telomerase, and 17 individuals with ALT positive tumors. The analysis of CDKN2A showed NDTMM GBMs had an increased minor allele frequency for the C500G (rs11515) polymorphism compared to those with telomerase and ALT positive GBMs (p = 0.002). Patients with the G500 allele had reduced survival that was independent of age, extent of surgery, and treatment. In the NDTMM group G500 allele carriers had increased loss of CDKN2A gene dosage compared to C500 homozygotes. An analysis of IDH1 mutations showed the R132H mutation was associated with ALT positive tumors, and was largely absent in NDTMM and telomerase positive tumors. In the ALT positive tumors cohort, IDH1 mutations were associated with a younger age for the affected individual. In conclusion, the G500 CDKN2A allele was associated with NDTMM GBMs from older individuals with poorer survival. Mutations in IDH1 were not associated with NDTMM GBMs, and instead were a marker for ALT positive tumors in younger individuals

Glycoprotein Ib activation by thrombin stimulates the energy metabolism in human platelets

<div><p>Thrombin-induced platelet activation requires substantial amounts of ATP. However, the specific contribution of each ATP-generating pathway <i>i</i>.<i>e</i>., oxidative phosphorylation (OxPhos) versus glycolysis and the biochemical mechanisms involved in the thrombin-induced activation of energy metabolism remain unclear. Here we report an integral analysis on the role of both energy pathways in human platelets activated by several agonists, and the signal transducing mechanisms associated with such activation. We found that thrombin, Trap-6, arachidonic acid, collagen, A23187, epinephrine and ADP significantly increased glycolytic flux (3–38 times <i>vs</i>. non-activated platelets) whereas ristocetin was ineffective. OxPhos (33 times) and mitochondrial transmembrane potential (88%) were increased only by thrombin. OxPhos was the main source of ATP in thrombin-activated platelets, whereas in platelets activated by any of the other agonists, glycolysis was the principal ATP supplier. In order to establish the biochemical mechanisms involved in the thrombin-induced OxPhos activation in platelets, several signaling pathways associated with mitochondrial activation were analyzed. Wortmannin and LY294002 (PI3K/Akt pathway inhibitors), ristocetin and heparin (GPIb inhibitors) as well as resveratrol, ATP (calcium-release inhibitors) and PP1 (Tyr-phosphorylation inhibitor) prevented the thrombin-induced platelet activation. These results suggest that thrombin activates OxPhos and glycolysis through GPIb-dependent signaling involving PI3K and Akt activation, calcium mobilization and protein phosphorylation.</p></div

Controlo químico de infestantes

Uma planta é considerada infestante quando nasce espontaneamente num local e momento indesejados, podendo interferir negativamente com a cultura instalada. As infestantes competem com as culturas para o espaço, a luz, água e nutrientes, podendo atrasar e prejudicar as operações de colheita, depreciar o produto final e assegurarem a reinfestação nas culturas seguintes. Dado o modo de propagação diferenciado das diversas espécies de infestantes, com as anuais a propagarem-se por semente e as perenes ou vivazes a assegurarem a sua propagação através de órgãos vegetativos (rizomas, bolbos, tubérculos, etc.), assim, também o seu controlo quer químico, quer mecânico terá que ser diferenciado, ou seja, para controlar infestantes anuais será suficiente destruir a sua parte aérea, enquanto para controlar infestantes perenes teremos que destruir os seus órgãos reprodutivos. O controlo de infestantes poderá ser químico, através da utilização de herbicidas, ou mecânico pela utilização de alfaias agrícolas, tais como a charrua de aivecas, a charrua de discos, a grade de discos, o escarificador e a fresa. Quando a técnica utilizada na instalação das culturas é a sementeira directa, o controlo das infestantes terá que ser obrigatoriamente químico, enquanto se o recurso à mobilização do solo for a técnica mais utilizada (sistema de mobilização tradicional ou sistema de mobilização reduzida), o controlo das infestantes tanto poderá ser químico como mecânico. Neste trabalho iremos abordar apenas, o controlo químico de infestantes

Human Papillomavirus E6/E7 Expression in Preeclampsia-Affected Placentae

Whether HPV is causative of pregnancy complications is uncertain. E6 and E7 affect functions underling preeclampsia (PET) in cultured trophoblasts, but whether E6 and E7 is produced in the placenta is uncertain. Here, we investigated whether E6/E7 was expressed in the placentae from pregnancies with PET, other pregnancy complications (fetal growth restriction (FGR) and diabetes mellitus), and uncomplicated pregnancies. Placental tissues collected from two geographical locations were subjected to RNAscope analyses of high- and low- risk E6/E7, and individual HPV types identified using an HPV array. High-risk E6/E7 expression was increased in both PET cohorts, (81% and 86% of patients positive for high-risk HPV DNA compared to 13% of control patients). Various HPV types were identified. Although HPV 18 was the most frequent in all cohorts, the majority of individuals had multiple HPV types (55% of the PET compared to 25% of the control cohort). Further evidence that E6 and E7 is present early when placental pathology underlying preeclampsia is established, is provided with the finding of high-risk E6/E7 in the first-trimester placenta anchoring trophoblast. In conclusion, E6/E7 expression and multiple HPV types were frequent in placentae from preeclampsia-complicated pregnancies

Demographic Characteristics of GBM Patients.

<p>*The significant difference for both the ALT+ versus NDTMM, and the ALT+ versus TEL+ GBM comparison. RT, radiotherapy; CT, chemotherapy.</p

The improved prognosis for C500 homozygotes is associated with retention of <i>p16^INK4a and p14^ARF</i>.

<p>Kaplan-Meier survival analysis from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026737#pone-0026737-g001" target="_blank">Figure 1A</a> with individuals with GBMs with no defined telomere maintenance mechanism further divided on exon 1α <i>(p16^INK4A)</i> gene dosage. Individuals homozygous for C500 were divided into those that had loss of homozygosity or loss of heterozygosity (C500 p16 loss) and those that retained exon 1α homozygosity (C500 p16 wt) by multiplex PCR of tumor DNA. The same division was made for G500 heterozygotes (G500 p16 loss and G500 p16 wt). The C500 p16 loss group had a significantly poorer survival to the C500 p16 wt group (p = 0.016, log-rank test with 95% CI). No difference in survival occurred for the G500 p16 loss and G500 p16 wt comparison. All associations for <i>p16^INK4a</i> pertained to <i>p14^ARF</i> due to identical exon 1α and exon 1β gene dosage.</p

Cox Proportional Hazards Model for Factors Affecting Survival.

<p>HR, Hazard ratio; 95% CI, 95% Hazard ratio confidence limits.</p

Patient survival with the G500 allele compared to C500 homozygotes for individuals with NDTMM and telomerase positive GBMs.

<p><b>A.</b> Kaplan-Meier survival analysis post tumor diagnosis for individuals with GBMs with no defined telomere maintenance mechanism (NDTMM). Survival data was available for all 38 individuals (the G500 homozygotes were excluded from the analysis). <b>B.</b> Kaplan-Meier survival analysis post tumor diagnosis for individuals with telomerase positive GBMs. Survival data was available for 44 individuals. Individuals genotyped as heterozygote for the C500G polymorphism (G500) in the 3′ <i>CDKN2A</i> UTR were associated with reduced survival compared to C500 homozygotes (C500) using a multi-variant Cox proportional hazards regression analysis (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0026737#pone-0026737-t003" target="_blank">Table 3</a>).</p