Polysome Profiling of a Human Glioblastoma Reveals Intratumoral Heterogeneity.

Glioblastoma (GBM) is one of the most aggressive cancers, with median survival of less than 2 years. Despite of considerable advance in molecular classification of GBMs, no improvements in therapy have been described. The scenario is further complicated by tumor heterogeneity and the relationship among genetic, transcriptional and functional findings. Classically, gene expression has been evaluated by steady-state mRNA, however, this does not take translational control into consideration, which contributes considerably to the composition of the proteome. In this study, we evaluated the transcriptomic and translatomic signature of a GBM obtained from a single patient focusing in tumor heterogeneity. In a sampling of eight fragments, we investigated the translation rates, mTORC1 and ERK1/2 pathways and identified both total and polysome associated mRNAs. An increased translation rate was observed in fragments with high-grade histological features. High-grade histology was also associated with the expression of genes related to extracellular matrix (ECM) and angiogenesis, in both transcriptomes and translatomes. However, genes associated with epithelial to mesenchymal transition and stress response, were observed only in translatomes from high-grade fragments. Overall, our results demonstrate that isolation of translated mRNA can be used to identify biomarkers and reveal previously unrecognized determinants of heterogeneity in GBMs.

Overexpression of mTOR and p(240-244)S6 in IDH1 Wild-Type Human Glioblastomas Is Predictive of Low Survival.

PI3K/Akt/mTOR pathway activation is a hallmark of high-grade gliomas, which prompted clinical trials for the use of PI3K and mTOR inhibitors. However, the poor results in the original trials suggested that better patient profiling was needed for such drugs. Thus, accurate and reproducible monitoring of mTOR complexes can lead to improved therapeutic strategies. In this work, we evaluated the expression and phosphorylation of mTOR, RAPTOR, and rpS6 in 195 human astrocytomas and 30 normal brain tissue samples. The expression of mTOR increased in glioblastomas, whereas mTOR phosphorylation, expression of RAPTOR, and expression and phosphorylation of rpS6 were similar between grades. Interestingly, the overexpression of total and phosphorylated mTOR as well as phosphorylated rpS6 (residues 240-244) were associated with wild-type IDH1 only glioblastomas. The expression and phosphorylation of mTOR and phosphorylation of rpS6 at residues 240-244 were associated with a worse prognosis in glioblastomas. Our results suggest that mTOR and rpS6 could be used as markers of overactivation of the PI3K-mTOR pathway and are predictive factors for overall survival in glioblastomas. Our study thus suggests that patients who harbor IDH1 wild-type glioblastomas might have increased benefit from targeted therapy against mTOR.

Characterization of rotavirus strains from hospitalized and outpatient children with acute diarrhoea in São Paulo, Brazil.

From August 1994 to July 1995, 234 faecal samples from children with or without acute diarrhoea were collected and tested. The group of children with acute diarrhoea (A) was subdivided into two subgroups: subgroup A(1) was made up of children with severe diarrhoea, dehydrated and who needed hospitalization and subgroup A(2) was composed of children who only needed outpatient care. Group B was composed of children without acute diarrhoea (controls). Rotavirus was detected in 36.7% (18/49), 22.0% (15/68) and 1.7% (2/117) patients in groups A(1), A(2) and B, respectively. Of the 35 positive samples in which rotaviruses were detected the VP7 genotypes G1, G2, G3, G5 and the mixture (G2 + G5) were found in 40.0, 11.4, 11.4, 22.9 and 2.9% of the samples, respectively. Also, the VP4 genotypes P[8], P[4] and P[6] were detected in 57.1, 31.4 and 5.7%, respectively. Rotavirus VP6 subgroups I and II were detected at a frequency of 22.4 and 54.3%, respectively. Rotavirus RNA segments had short and long electrophoresis profiles in 20.0 and 51.4% of the cases, respectively. The severity of the disease was not related to a specific G and P types, subgroup or electropherotype.