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Astrocytic tumors, including astrocytomas and glioblastomas, are the most common type of primary brain tumors. Treatment for glioblastomas includes radiotherapy, chemotherapy with temozolomide (TMZ) and surgical ablation. Despite certain therapeutic advances, the survival time of patients is no longer than 12-14 months. Cancer cells overexpress the neuronal isoform of nitric oxide synthase (nNOS). In the present study, it was examined whether the nNOS enzyme serves a role in the damage of astrocytoma (U251MG and U138MG) and glioblastoma (U87MG) cells caused by TMZ. First, TMZ (250 μM) triggered an increase in oxidative stress at 2, 48 and 72 h in the U87MG, U251MG and U138MG cell lines, as revealed by 2',7'-dichlorofluorescin-diacetate assay. The drug also reduced cell viability, as measured by MTT assay. U87MG cells presented a more linear decline in cell viability at time-points 2, 48 and 72 h, compared with the U251MG and U138MG cell lines. The peak of oxidative stress occurred at 48 h. To examine the role of NOS enzymes in the cell damage caused by TMZ, N(ω)-nitro-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI) were used. L-NAME increased the cell damage caused by TMZ while reducing the oxidative stress at 48 h. The preferential nNOS inhibitor 7-NI also improved the TMZ effects. It caused a 12.8% decrease in the viability of TMZ-injured cells. Indeed, 7-NI was more effective than L-NAME in restraining the increase in oxidative stress triggered by TMZ. Silencing nNOS with a synthetic small interfering (si)RNA (siRNAnNOShum_4400) increased by 20% the effects of 250 μM of TMZ on cell viability (P<0.05). Hoechst 33342 nuclear staining confirmed that nNOS knock-down enhanced TMZ injury. In conclusion, our data reveal that nNOS enzymes serve a role in the damage produced by TMZ on astrocytoma and glioblastoma cells. RNA interference with nNOS merits further studies in animal models to disclose its potential use in brain tumor anticancer therapy. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) regulate gene expression at posttranscriptional level by triggering RNA interference. In such a sense, aberrant expressions of miRNAs play critical roles in the pathogenesis of many disorders, including Parkinson’s disease (PD). Controlling the level of specific miRNAs in the brain is thus a promising therapeutic strategy for neuroprotection. A fundamental need for miRNA regulation (either replacing or inhibition) is a carrier capable of delivering oligonucleotides into brain cells. This study aimed to examine a polymeric magnetic particle, Neuromag®, for delivery of synthetic miRNA inhibitors in the rat central nervous system. We injected the miRNA inhibitor complexed with Neuromag® into the lateral ventricles next to the striatum, by stereotaxic surgery. Neuromag efficiently delivered oligonucleotides in the striatum and septum areas, as shown by microscopy imaging of fluorescein isothiocyanate (FITC)-labeled oligos in astrocytes and neurons. Transfected oligos showed efficacy concerning miRNA inhibition. Neuromag®-structured miR-134 antimiR (0.36 nmol) caused a significant 0.35 fold decrease of striatal miR-134, as revealed by real-time quantitative polymerase chain reaction (RT-qPCR). In conclusion, the polymeric magnetic particle Neuromag® efficiently delivered functional miRNA inhibitors in brain regions surrounding lateral ventricles, particularly the striatum. This delivery system holds potential as a promising miRNA-based disease-modifying drug and merits further pre-clinical studies using animal models of PD. [ABSTRACT FROM AUTHOR]