No abstract

Suicide gene therapy is based on the introduction into tumor cells of a viral or a bacterial gene, which allows the conversion of a non-toxic compound into a lethal drug. Although suicide gene therapy has been successfully used in a large number of in vitro and in vivo studies, its application to cancer patients has not reached the desirable clinical significance. However, recent reports on pre-clinical cancer models demonstrate the huge potential of this strategy when used in combination with new therapeutic approaches. In this review, we summarize the different suicide gene systems and gene delivery vectors addressed to cancer, with particular emphasis on recently developed systems and associated bystander effects. In addition, we review the different strategies that have been used in combination with suicide gene therapy and provide some insights into the future directions of this approach, particularly towards cancer stem cell eradication.

SUMMARY Macroautophagy (hereafter autophagy) is the major pathway by which macromolecules and organelles are degraded. Autophagy is regulated by the mTOR signaling pathway – the focal point for integration of metabolic information, with mTORC1 playing a central role in balancing biosynthesis and catabolism. Of the various inputs to mTORC1, the amino acid sensing pathway is among the most potent. Based upon transcriptome analysis of neurons subjected to nutrient deprivation, we identified let-7 microRNA as capable of promoting neuronal autophagy. We found that let-7 activates autophagy by coordinately down-regulating the amino acid sensing pathway to prevent mTORC1 activation. Let-7 induced autophagy in the brain to eliminate protein aggregates, establishing its physiological relevance for in vivo autophagy modulation. Moreover, peripheral delivery of let-7 anti-miR repressed autophagy in muscle and white fat, suggesting that let-7 autophagy regulation extends beyond CNS. Hence, let-7 plays a central role in nutrient homeostasis and proteostasis regulation in higher organisms.

Polyglutamine (polyQ) disorders are a group of nine neurodegenerative diseases that share a common genetic cause, which is an expansion of CAG repeats in the coding region of the causative genes that are otherwise unrelated. The trinucleotide expansion encodes for an expanded polyQ tract in the respective proteins, resulting in toxic gain-of-function and eventually in neurodegeneration. Currently, no disease-modifying therapies are available for this group of disorders. Nevertheless, given their monogenic nature, polyQ disorders are ideal candidates for therapies that target specifically the gene transcripts. Antisense oligonucleotides (ASOs) have been under intense investigation over recent years as gene silencing tools. ASOs are small synthetic single-stranded chains of nucleic acids that target specific RNA transcripts through several mechanisms. ASOs can reduce the levels of mutant proteins by breaking down the targeted transcript, inhibit mRNA translation or alter the maturation of the pre-mRNA via splicing correction. Over the years, chemical optimization of ASO molecules has allowed significant improvement of their pharmacological properties, which has in turn made this class of therapeutics a very promising strategy to treat a variety of neurodegenerative diseases. Indeed, preclinical and clinical strategies have been developed in recent years for some polyQ disorders using ASO therapeutics. The success of ASOs in several animal models, as well as encouraging results in the clinic for Huntington’s disease, points towards a promising future regarding the application of ASO-based therapies for polyQ disorders in humans, offering new opportunities to address unmet medical needs for this class of disorders. This review aims to present a brief overview of key chemical modifications, mechanisms of action and routes of administration that have been described for ASO-based therapies. Moreover, it presents a review of the most recent and relevant preclinical and clinical trials that have tested ASO therapeutics in polyQ disorders.

Background Cell penetrating peptides have been successfully used to mediate the intracellular delivery of a wide variety of molecules of pharmacological interest. The main aim of the present work was to evaluate the potential of the S4 13 -PV cell penetrating peptide to mediate the intracellular delivery of plasmid DNA, aiming at its use in gene therapy applications. The S4 13 -PV cell penetrating peptide is a chimeric peptide that results from the combination of a cell penetrating sequence derived from the Dermaseptin S4 peptide with the nuclear localization signal present in the Simian Virus 40 (SV40) large T antigen.

Machado-Joseph disease (MJD) is a dominantly inherited disorder originally described in people of Portuguese descent, and associated with the expansion of a CAG tract in the coding region of the causative gene MJD1/ATX3. The CAG repeats range from 10 to 51 in the normal population and from 55 to 87 in SCA3/MJD patients. MJD1 encodes ataxin-3, a protein whose physiological function has been linked to ubiquitin-mediated proteolysis. Despite the identification of the causative mutation, the pathogenic process leading to the neurodegeneration observed in the disease is not yet completely understood. In the past years, several studies identified different molecular mechanisms and cellular pathways as being impaired or deregulated in MJD. Autophagy, proteolysis or post-translational modifications, among other processes, were implicated in MJD pathogenesis. From these studies it was possible to identify new targets for therapeutic intervention, which in some cases proved successful in models of disease.

No abstract

Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3, the most common dominant spinocerebellar ataxia (SCA) worldwide, is caused by over-repetition of a CAG repeat in the ATXN3/MJD1 gene, which translates into a polyglutamine tract within the ataxin-3 protein. There is no treatment for this fatal disorder. Despite evidence of the safety and efficacy of mesenchymal stromal cells (MSCs) in delaying SCA disease progression in exploratory clinical trials, unanticipated regression of patients to the status prior to treatment makes the investigation of causes and solutions urgent and imperative. In the present study, we compared the efficacy of a single intracranial injection with repeated systemic MSC administration in alleviating the MJD phenotype of two strongly severe genetic rodent models. We found that a single MSC transplantation only produces transient effects, whereas periodic administration promotes sustained motor behavior and neuropathology alleviation, suggesting that MSC therapies should be re-designed to get sustained beneficial results in clinical practice. Furthermore, MSC promoted neuroprotection, increased the levels of GABA and glutamate, and decreased the levels of Myo-inositol, which correlated with motor improvements, indicating that these metabolites may serve as valid neurospectroscopic biomarkers of disease and treatment. This study makes important contributions to the design of new clinical approaches for MJD and other SCAs/polyglutamine disorders.