Synthetic photoswitches have been known for many years, but their usefulness in biology, pharmacology, and medicine has only recently been systematically explored. Over the past decade photopharmacology has grown into a vibrant field. As the photophysical, pharmacodynamic, and pharmacokinetic properties of photoswitches, such as azobenzenes, have become established, they have been applied to a wide range of biological targets. These include transmembrane proteins (ion channels, transporters, G protein-coupled receptors, receptor-linked enzymes), soluble proteins (kinases, proteases, factors involved in epigenetic regulation), lipid membranes, and nucleic acids. In this review, we provide an overview of photopharmacology using synthetic switches that have been applied in vivo, i.e., in living cells and organisms. We discuss the scope and limitations of this approach to study biological function and the challenges it faces in translational medicine. The relationships between synthetic photoswitches, natural...

In Vivo Photopharmacology.

Reactive oxygen species (ROS)-induced apoptosis is a promising treatment strategy for malignant neoplasms. However, current systems are highly dependent on oxygen status and/or external stimuli to generate ROS, which greatly limit their therapeutic efficacy particularly in hypoxic tumors. Herein, we develop a biomimetic nanoflower based on self-assembly of nanozymes that can catalyze a cascade of intracellular biochemical reactions to produce ROS in both normoxic and hypoxic conditions without any external stimuli. In our formulation, PtCo nanoparticles are firstly synthesized and used to direct the growth of MnO2. By adjusting the ratio of reactants, highly-ordered MnO2@PtCo nanoflowers with excellent catalytic efficiency are obtained, where PtCo behaves as oxidase mimic and MnO2 functions as catalase mimic. In this way, the well-defined MnO2@PtCo nanoflowers not only can relieve hypoxic condition but also induce cell apoptosis significantly through ROS-mediated mechanism, thereby resulting in remarkable and specific inhibition of tumor growth.

/pdf/biomimetic-nanoflowers-by-self-assembly-of-nanozymes-to-56rvbgsmvm.pdf

Biomimetic nanoflowers by self-assembly of nanozymes to induce intracellular oxidative damage against hypoxic tumors.

Photodynamic therapy (PDT) is considered a promising approach for the treatment of cancer and is achieved via the photosensitizer (PS)-mediated incomplete reduction of oxygen upon light irradiation, which generates high levels of reactive oxygen species (ROS) to induce potent vascular damage and to directly kill tumor cells. However, there is an undesirable impediment with this approach in that tumor tissues generally suffer from serious hypoxia, which significantly affects the efficiency of PDT. Additionally, PDT that consumes oxygen will further aggravate tumor hypoxia, thus potentially leading to multiple undesirable consequences, such as angiogenesis, tumor invasiveness, and tumor metastasis. This mini-review provides a comprehensive overview of the recent research progress on overcoming or utilizing tumor hypoxia to enhance the therapeutic efficacy of PDT.

Manipulating tumor hypoxia toward enhanced photodynamic therapy (PDT)

Light is a nearly ideal stimulus for molecular systems. It delivers information encoded in the form of wavelengths and their intensities with high precision in space and time. Light is a mild trigger that does not permanently contaminate targeted samples. Its energy can be reversibly transformed into molecular motion, polarity, or flexibility changes. This leads to sophisticated functions at the supramolecular and macroscopic levels, from light-triggered nanomaterials to photocontrol over biological systems. New methods and molecular adapters of light are reported almost daily. Recently reported applications of photoresponsive systems, particularly azobenzenes, spiropyrans, diarylethenes, and indigoids, for smart materials and photocontrol of biological setups are described herein with the aim to demonstrate that the 21st century has become the Age of Enlightenment-"Le siecle des Lumieres"-in molecular sciences.

Recent Implementations of Molecular Photoswitches into Smart Materials and Biological Systems.

Molecular photoswitches enable dynamic control of processes with high spatiotemporal precision, using light as external stimulus, and hence are ideal tools for different research areas spanning from chemical biology to smart materials. Photoswitches are typically organic molecules that feature extended aromatic systems to make them responsive to (visible) light. However, this renders them inherently lipophilic, while water-solubility is of crucial importance to apply photoswitchable organic molecules in biological systems, like in the rapidly emerging field of photopharmacology. Several strategies for solubilizing organic molecules in water are known, but there are not yet clear rules for applying them to photoswitchable molecules. Importantly, rendering photoswitches water-soluble has a serious impact on both their photophysical and biological properties, which must be taken into consideration when designing new systems. Altogether, these aspects pose considerable challenges for successfully applying molecular photoswitches in aqueous systems, and in particular in biologically relevant media. In this review, we focus on fully water-soluble photoswitches, such as those used in biological environments, in both in vitro and in vivo studies. We discuss the design principles and prospects for water-soluble photoswitches to inspire and enable their future applications.

/pdf/molecular-photoswitches-in-aqueous-environments-4qmjy1s1mx.pdf

Molecular photoswitches in aqueous environments

Conventional photodynamic treatment strategies are based on the principle of activating molecular oxygen in situ by light, mediated by a photosensitizer, which leads to the generation of reactive oxygen species and thereby causes cell death. A diarylethene-derived peptidomimetic is presented that is suitable for photodynamic cancer therapy without any involvement of oxygen. This light-sensitive molecule is not a mediator but is itself the cytotoxic agent. As a derivative of the cyclic amphiphilic peptide gramicidin S, the peptidomimetic exists in two thermally stable photoforms that are interconvertible by light of different wavelengths. The isomer generated by visible light shows much stronger toxicity against tumor cells than the UV-generated isomer. First in vivo applications are demonstrated on a tumor animal model to illustrate how the peptidomimetic can be administered in the less toxic form and then activated locally in a solid tumor by visible light.

Direct Photocontrol of Peptidomimetics: An Alternative to Oxygen-Dependent Photodynamic Cancer Therapy

The mechanisms of VEGF-mediated effects on endothelial cells during cancer development and progression is not clear. In present study the biological effects of VEGF, VEGF-rich culture medium of peritoneal macrophages from mice with Lewis lung carcinoma were studied on MAEC cell line under conditions of unfed culture. We have shown that VEGF increased cell proliferation by the 5th day of culturing vs control and anti-VEGF-treated cells. This effect was associated with increased consumption of glucose and NO production by the 2nd day while decreased – on the 5th day of cell culturing. VEGF-mediated NO production was dependent on Ca2+ ions. Block of Ca2+-channels (LaCl3) had more pronounced inhibitory effect vs chelator of Ca2+ ions (EDTA). It was shown that peritoneal macrophages are the main suppliers of VEGF at tumor angiogenesis, as evidenced by the data obtained on model system of endothelial cells synchronized in G0/G1 phase.

/pdf/the-mechanism-of-vegf-mediated-endothelial-cells-survival-m9e9euuitb.pdf

The mechanism of VEGF-mediated endothelial cells survival and proliferation in conditions of unfed-culture.

P2.01-091 The Anticancer Effect of Techoic Acids on Lewis Lung Carcinoma Model

The Influence of Nimotuzumab in Combination with EGF on the Cell Cycle and Apoptotic Level of Tumor Cells

P4 mechanism of proangiogenic activity of mitocorrectin on endothelial cells in vitro

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