Abnormal RNA stability in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share key features, including accumulation of the RNA-binding protein TDP-43. TDP-43 regulates RNA homeostasis, but it remains unclear whether RNA stability is affected in these disorders. We use Bru-seq and BruChase-seq to assess genome-wide RNA stability in ALS patient-derived cells, demonstrating profound destabilization of ribosomal and mitochondrial transcripts. This pattern is recapitulated by TDP-43 overexpression, suggesting a primary role for TDP-43 in RNA destabilization, and in postmortem samples from ALS and FTD patients. Proteomics and functional studies illustrate corresponding reductions in mitochondrial components and compensatory increases in protein synthesis. Collectively, these observations suggest that TDP-43 deposition leads to targeted RNA instability in ALS and FTD, and may ultimately cause cell death by disrupting energy production and protein synthesis pathways.

Antisense oligonucleotide targeting eukaryotic translation initiation factor 4E reduces growth and enhances chemosensitivity of non-small-cell lung cancer cells.

Elevated levels of eukaryotic translation initiation factor 4E (eIF4E) enhance translation of many malignancy-related proteins, such as vascular endothelial growth factor (VEGF), c-Myc and osteopontin. In non-small-cell lung cancer (NSCLC), levels of eIF4E are significantly increased compared with normal lung tissue. Here, we used an antisense oligonucleotide (ASO) to inhibit the expression of eIF4E in NSCLC cell lines. eIF4E levels were significantly reduced in a dose-dependent manner in NSCLC cells treated with eIF4E-specific ASO (4EASO) compared with control ASO. Treatment of NSCLC cells with the 4EASO resulted in decreased cap-dependent complex formation, decreased cell proliferation and increased sensitivity to gemcitabine. At the molecular level, repression of eIF4E with ASO resulted in decreased expression of the oncogenic proteins VEGF, c-Myc and osteopontin, whereas expression of ß-actin was unaffected. Based on these findings, we conclude that eIF4E-silencing therapy alone or in conjunction with chemotherapy represents a promising approach deserving of further investigation in future NSCLC clinical trials.

Compatibility studies of promethazine hydrochloride with tablet excipients by means of thermal and non-thermal methods.

The compatibility of promethazine hydrochloride (PMZ) with various tableting excipients has been investigated by isothermal stress testing (IST) and differential scanning calorimetry (DSC). DSC thermograms of PMZ and each of the excipients investigated were compared with their corresponding physical mixtures (1:1) for evaluation. Furthermore, Fourier transform infrared spectroscopy (FTIR) data was used to corroborate the results of DSC and IST. A preliminary sustained release tablet formulation of the drug, prepared using compatible excipients, was stored under accelerated storage conditions (40 degrees C/75% RH) and analyzed for stability, drug release and bioadhesion characteristics for up to 3 months. Based on DSC results alone, drug-excipient interactions were observed with Pearlitol SD200, lactose monohydrate and zinc stearate. Chromatographic analysis of the stressed binary mixture (stored at 55 degrees C for 3 weeks) containing PMZ-lactose monohydrate showed brown discoloration indicating potential interaction. However, stressed physical mixtures of PMZ-Pearlitol SD200 and PMZ-zinc stearate indicated compatibility as opposed to the thermal analysis. The tablet formulation was found to be very stable after 3 months of storage at accelerated stability conditions. Also, the release profiles and bioadhesive properties were found to be unaltered. Thus, both thermal and non-thermal methods were utilized to successfully evaluate the compatibility of excipients with PMZ and the tablet formulation was found to be stable.

Development and validation of a HPLC method for the analysis of promethazine hydrochloride in hot-melt extruded dosage forms.

A simple and rapid stability-indicating HPLC method was developed for determination of promethazine hydrochloride (PMZ) in hot-melt extruded (HME) films and sustained release tablets. Chromatographic separation was achieved on a 150 mm x 4.6 mm i.d., 3 microm particle size, C8 (2) column with acetonitrile-25mM phosphate buffer (pH 7.0), 50:50 (v/v) as mobile phase at a flow rate of 1 mL min(-1). Quantitation was achieved with UV detection at 249 nm based on peak area. The method was validated in terms of linearity, precision, accuracy, robustness specificity, limits of detection and quantitation according to ICH guidelines. Specificity was validated by subjecting the drug to acid, base, oxidative, reductive and dry heat degradations. None of the degradation products obtained by forced degradation interfered with the PMZ peak. The method was successfully applied for assessing the stability of the drug in the HME films and sustained release tablet formulations. In addition, uniformity of PMZ content in HME films was also determined using the method developed. Excipients present in either of the dosage forms analyzed did not interfere with the analysis indicating the specificity of the method. Due to its simplicity and accuracy, the method is suitable for application to various dosage forms.