A combination of Light On gene expression system and tumor microenvironment-responsive nanoparticle delivery system for targeted breast cancer therapy

A light-switchable transgene system called LightOn gene expression system could regulate gene expression with a high on/off ratio under blue light,and have great potential for spatiotemporally controllable gene expression.We developed a nanoparticle drug delivery system(NDDS)to achieve tumor microenvironment-responsive and targeted delivery of diphtheria toxin A(DTA)fragment-encoded plasmids to tumor sites.The expression of DTA was induced by exposure to blue light.Nanoparticles composed of polyethylenimine and vitamin E succinate linked by a disulfide bond,and PEGylated hyaluronic acid modified with RGD peptide,accumulated in tumor tissues and were actively internalized into 4 T1 cells via dual targeting to CD44 andαvβ3 receptors.The LightOn gene expression system was able to control target protein expression through regulation of the intensity or duration of blue light exposure.In vitro studies showed that lisht-induced DTA expression reduced 4 T1 cell viability and induced apoptosis.Furthermore,the LightOn gene expression system enabled spatiotemporal control of the expression of DTA in a mouse 4 T1 tumor xenogratt model,which resulted in excellent antitumor effects,reduced tumor angiogenesis,and no systemic toxicity.The combination of the LightOn gene expression system and NDDS may be an effective strategy for treatment of breast cancer.

Spatiotemporal Imaging of Cellular Energy Metabolism with Genetically-Encoded Fluorescent Sensors in Brain

The brain has very high energy requirements and consumes 20% of the oxygen and 25% of the glucose in the human body. Therefore, the molecular mechanism under- lying how the brain metabolizes substances to support neural activity is a fundamental issue for neuroscience studies. A well-known model in the brain, the astrocyte- neuron lactate shuttle, postulates that glucose uptake and glycolytic activity are enhanced in astrocytes upon neu- ronal activation and that astrocytes transport lactate into neurons to fulfill their energy requirements. Current evidence for this hypothesis has yet to reach a clear consensus, and new concepts beyond the shuttle hypothesis are emerging. The discrepancy is largely attributed to the lack of a critical method for real-time monitoring of metabolic dynamics at cellular resolution. Recent advances in fluorescent protein-based sensors allow the generation of a sensitive, specific, real-time readout of subcellular metabolites and fill the current technological gap. Here,we summarize the development of genetically encoded metabolite sensors and their applications in assessing cell metabolism in living cells and in vivo, and we believe that these tools will help to address the issue of elucidating neural energy metabolism.