Background

CD44 has long been associated with glioma invasion while, more recently, CD155 has been implicated in playing a similar role. Notably, these two receptors have been shown closely positioned on monocytes.

Methods and Findings

In this study, an up-regulation of CD44 and CD155 was demonstrated in established and early-passage cultures of glioblastoma. Total internal reflected fluorescence (TIRF) microscopy revealed close proximity of CD44 and CD155. CD44 antibody blocking and gene silencing (via siRNA) resulted in greater inhibition of invasion than that for CD155. Combined interference resulted in 86% inhibition of invasion, although in these investigations no obvious evidence of synergy between CD44 and CD155 in curbing invasion was shown. Both siRNA-CD44 and siRNA-CD155 treated cells lacked processes and were rounder, while live cell imaging showed reduced motility rate compared to wild type cells. Adhesion assay demonstrated that wild type cells adhered most efficiently to laminin, whereas siRNA-treated cells (p<0.0001 for both CD44 and CD155 expression) showed decreased adhesion on several ECMs investigated. BrdU assay showed a higher proliferation of siRNA-CD44 and siRNA-CD155 cells, inversely correlated with reduced invasion. Confocal microscopy revealed overlapping of CD155 and integrins (β1, αvβ1 and αvβ3) on glioblastoma cell processes whereas siRNA-transfected cells showed consequent reduction in integrin expression with no specific staining patterns. Reduced expression of Rho GTPases, Cdc42, Rac1/2/3, RhoA and RhoB, was seen in siRNA-CD44 and siRNA-CD155 cells. In contrast to CD44-knockdown and ‘double’-knockdown cells, no obvious decrease in RhoC expression was observed in CD155-knockdown cells.

Conclusions

This investigation has enhanced our understanding of cell invasion and confirmed CD44 to play a more significant role in this biological process than CD155. Joint CD44/CD155 approaches may, however, merit further study in therapeutic targeting of infiltrating glioma cells.

Avian influenza A viruses continue to cause disease outbreaks in humans, and extrapulmonary infection is characteristic. In vitro studies demonstrate the activity of oseltamivir against avian viruses of the H5, H7 and H9 subtypes. In animal models of lethal infection, oseltamivir treatment and prophylaxis limit viral replication and improve survival. Outcomes are influenced by the virulence of the viral strain, dosage regimen and treatment delay; it is also critical for the compound to act systemically. Observational data on oseltamivir treatment in the early stages of disease suggest it is useful for improving survival in patients infected with H5 viruses, and drug-selected resistance has only rarely been reported. The WHO strongly recommends oseltamivir for the treatment of confirmed or suspected cases of human H5 infection and prophylaxis of those at high risk of infection. In addition to oral dosing, nasogastric administration appears to be a viable option for the management of severely ill patients, as is the use of higher doses and prolonged schedules. F. Hoffmann-La Roche Ltd, the manufacturer of oseltamivir, is developing a mathematical model to allow rapid prediction of appropriate dosage regimens for any future pandemic. Roche is also funding the Avian Influenza Registry, an online database that aims to collect information from clinicians worldwide on the course of avian influenza in humans.

The threat of potential pandemic influenza requires a reevaluation of licensed therapies for the prophylaxis or treatment of avian H5N1 infection that may adapt to man. Among the therapies considered for use in pandemic influenza is the co-administration of ion channel and neuraminidase inhibitors, both to potentially increase efficacy as well as to decrease the emergence of resistant isolates. To better understand the potential for drug interactions, a cross-over, randomized, open-label trial was conducted with amantadine, 100 mg po bid, and oseltamivir, 75 mg po bid, given alone or in combination for 5 days. Each subject (N = 17) served as their own control and was administered each drug alone or in combination, with appropriate wash-out. Co-administration with oseltamivir had no clinically significant effect on the pharmacokinetics (PK) of amantadine [mean ratios (90% CI) for AUC0-12 0.93 (0.89, 0.98) and Cmax 0.96 (0.90, 1.02)]. Similarly, amantadine co-administration did not affect oseltamivir PK [AUC0-12 0.92 (0.86, 0.99) and Cmax 0.85 (0.73, 0.99)] or the PK of the metabolite, oseltamivir carboxylate [AUC0-12 0.98 (0.95, 1.02) and Cmax 0.95 (0.89, 1.01)]. In this small trial there was no evidence of an increase in adverse events. Although many more subjects would need to be studied to rule out a synergistic increase in adverse events, the combination in this small human drug-drug interaction trial appears safe and without pharmacokinetic consequences.

Trial Registration

ClinicalTrials.gov NCT00416962

MRG15 is a highly conserved protein, and orthologs exist in organisms from yeast to humans. MRG15 associates with at least two nucleoprotein complexes that include histone acetyltransferases and/or histone deacetylases, suggesting it is involved in chromatin remodeling. To study the role of MRG15 in vivo, we generated knockout mice and determined that the phenotype is embryonic lethal, with embryos and the few stillborn pups exhibiting developmental delay. Immunohistochemical analysis indicates that apoptosis in Mrg15−/− embryos is not increased compared with wild-type littermates. However, the number of proliferating cells is significantly reduced in various tissues of the smaller null embryos compared with control littermates. Cell proliferation defects are also observed in Mrg15−/− mouse embryonic fibroblasts. The hearts of the Mrg15−/− embryos exhibit some features of hypertrophic cardiomyopathy. The increase in size of the cardiomyocytes is most likely a response to decreased growth of the cells. Mrg15−/− embryos appeared pale, and microarray analysis revealed that α-globin gene expression was decreased in null versus wild-type embryos. We determined by chromatin immunoprecipitation that MRG15 was recruited to the α-globin promoter during dimethyl sulfoxide-induced mouse erythroleukemia cell differentiation. These findings demonstrate that MRG15 has an essential role in embryonic development via chromatin remodeling and transcriptional regulation.

The host suitability of diverse races and gene pools of common bean (Phaseolus vulgaris) for multiple isolates of Heterodera glycines was studied. Twenty P. vulgaris genotypes, representing three of the six races within the two major germplasm pools, were tested in greenhouse experiments to determine their host suitability to five H. glycines isolates. Phaseolus vulgaris genotypes differed in their host suitability to different H. glycines isolates. While some common bean lines were excellent hosts for some H. glycines isolates, no common bean line was a good host for all isolates. Some bean lines from races Durango and Mesoamerica, representing the Middle America gene pool, were resistant to all five nematode isolates. Other lines, from both the Andean and Middle America gene pools, had differential responses for host suitability to the different isolates of H. glycines.

Differentiation of skeletal muscle is affected in myotonic dystrophy (DM) patients. Analysis of cultured myoblasts from DM patients shows that DM myoblasts lose the capability to withdraw from the cell cycle during differentiation. Our data demonstrate that the expression and activity of the proteins responsible for cell cycle withdrawal are altered in DM muscle cells. Skeletal muscle cells from DM patients fail to induce cytoplasmic levels of a CUG RNA binding protein, CUGBP1, while normal differentiated cells accumulate CUGBP1 in the cytoplasm. In cells from normal patients, CUGBP1 up-regulates p21 protein during differentiation. Several lines of evidence show that CUGBP1 induces the translation of p21 via binding to a GC-rich sequence located within the 5′ region of p21 mRNA. Failure of DM cells to accumulate CUGBP1 in the cytoplasm leads to a significant reduction of p21 and to alterations of other proteins responsible for the cell cycle withdrawal. The activity of cdk4 declines during differentiation of cells from control patients, while in DM cells cdk4 is highly active during all stages of differentiation. In addition, DM cells do not form Rb/E2F repressor complexes that are abundant in differentiated cells from normal patients. Our data provide evidence for an impaired cell cycle withdrawal in DM muscle cells and suggest that alterations in the activity of CUGBP1 causes disruption of p21-dependent control of cell cycle arrest.