Latest ArticlesNatural products and their derivatives are important components of anti-tumor drugs. Currently, anti-tumor drugs derived from natural products which are in clinical practice are mainly conventional cytotoxic or molecularly targeted drugs. Their application is limited by drug-related side effects and drug resistance. Recent studies have shown that anti-tumor natural products often act on multiple targets in tumor cells and in turn interfere with multiple processes in tumorigenesis and development. As tumor is a systemic disease induced by multiple factors, multi-targeted natural products possess unique potential in tumor therapy. However, the targets and mechanisms of the discovered multi-targeted antitumor natural products remain elusive, which limits their further development and application. This review summarized the research progress in the mechanism of action, target identification, and structure optimization of multi-targeted anti-tumor natural products exemplified by a few typical compounds. The research and development of these agents have also been proposed.
Protein kinases are intimately involved in the pathogenesis of many diseases such as cancer, inflammation, and autoimmune and neurological diseases. Therefore, kinases have been widely studied as drug targets over the past three decades. As of April, 2020, the FDA had approved 59 small molecule kinase inhibitors(SMKIs)in the emerging field of targeted drug therapy. This paper focuses on the biochemistry and pharmacology of these59 SMKIs and 121 SMKIs for which structures can be retrieved and that are now in phase Ⅱ and Ⅲ clinical trials.In addition, this paper also conducts a simple analysis of several popular targets and their inhibitors.
Transporters have a great influence on the transportation and distribution of drugs in the body. On the one hand, solute carrier transporters could transport drugs into tissues and organs, which may improve the oral bioavailability or change the tissue-distribution of the drugs. On the other hand, the ATP-binding cassette could pump some drugs out of the cell, which decreases the intracellular drug concentrations and leads to drug resistance.This paper summarizes the distribution, substrate characteristics and drug design strategies of several important drug transporters, such as improving bioavailability by prodrug design, introducing acid group to improve hepatic selectivity and adjusting the polarity of compounds to decrease efflux ratio.
With high selectivity and potency, target protein degradation technology has recently emerged as a strategy for drug discovery and design. Proteolysis-targeting chimeras(PROTAC) function as inducers for the degradation of target proteins and are a research focus in drug development. Current research on PROTAC mainly revolves around the rational design of PROTAC molecules, the discovery of new E3 ubiquitin ligase ligands and improvement in drug targeting. In this review, we focus on the PROTAC linker and its effects on the generation of the E3 enzyme-PROTAC-target protein ternary complex from three standpoints: length, binding site and chemical properties. We discuss the influences of the linker on the efficacy and the selectivity of PROTAC molecules.
Biomarkers are defined as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention.Biomarkers can help the decision-making process for new drug research and development, provide guidance for the early clinical development of candidate drugs and reduce the risk of failure. Therefore, as a key factor in the development of new drugs, the discovery and research on biomarkers has increased the interest of the pharmaceutical industry and regulatory agencies. Guidelines on the development and use of biomarkers have been issued by drug regulatory agencies including the EMA, FDA and ICH. Biomarkers are encouraged to be used to facilitate drug development by these relevant regulatory agencies, and also to be used to monitor the safety and efficacy of drugs in post-marketing drug surveillance. The application of biomarkers is encouraged at different stages of a drug's life cycle, including at the stage of basic science research and target identification, prototype design or discovery, preclinical development, clinical development, FDA filling/approval and launch, as well as post-marketing was reviewed. The identification, development, and application of biomarkers in pharmaceutical research is discussed.
During growth and progression, the microenvironment of tumors suffers a series of abnormal characteristics, which include hypoxia, acid pH, increased oxidative stress, excess glutathione(GSH), as well as certain overexpressed enzymes. Although affect or limit the cancer therapeutic outcomes, these factors provide possible approaches to strategies for cancer detection and novel therapy at the same time. Recently, based on these properties of the tumor microenvironment(TME), various kinds of responsive nano-platforms have been continuously developed and applied in cancer theranostics preliminarily. Thus, this review would introduce the typical features of TME firstly, then detailly summarize the design principles and research progress of corresponding hypoxiaresponsive, pH-responsive, redox-responsive, enzyme-responsive, dual-responsive and multi-responsive nanoplatforms. Finally, the challenges and the perspectives of the TME-responsive nano-platforms are briefly discussed.
Compared with normal tissues and cells, the tumor microenvironment has significant differences.For example, glutathione-related metabolic enzymes and reactive oxygen species are highly expressed in different subcellular structures, resulting in an unbalanced redox state. Aiming at the specific redox state in tumor tissues and cells, a series of small molecule prodrug self-assembled nanoparticles can be designed and connected by intelligent response linkers including disulfide bonds, sulfide bonds, and selenium bonds, thioketal bonds, etc. The in vitro and in vivo efficiency and metabolic mode of these nanoparticles are related to the type of linker. This review will summarize the tumor redox microenvironment, the design of intelligent responsive small molecule prodrug nanoparticles, and the metabolic pathways of small molecule prodrug nanoparticles with different connecting linkers and their relationship with drug efficacy.
Nanoparticles have better applicability in the detection, treatment of cancer and various difficult diseases, but mononuclear phagocytosis system can seriously shorten the time of nanoparticles in vivo circulation, reduce the drug efficacy. The protein crown formed on the surface of the nanoparticle after entering the body can change its surface properties, interfere with the recognition of phagocytes, and thus affect its circulation time in vivo.This article outlines the general composition and formation process of protein crowns. It also summarizes the influence of the physical and chemical properties of nanoparticles, such as particle size, surface charge, hydrophilicity and surface materials on the formation of protein crowns. The protein crown affects the circulation of nanoparticles in vivo, mainly because the adsorbed opsonic protein promotes cell phagocytosis. Therefore, we also introduce the method of using protein crowns to promote the long circulation of nanoparticles in vivo. By designing appropriate physical and chemical properties, surface modification, and directed design of protein crowns, the adsorption of proteins on the surface of nanoparticles can be reduced. Therefore, it can reduce the clearance of nanoparticles in the mononuclear phagocytic system(mainly the phagocytes of the liver and spleen), and achieve the goal of long circulation of nanoparticles in the body.
Antibody-drug conjugates(ADCs) are one of the most important classes of anticancer therapeutics.Human epidermal growth factor receptor-2(HER2), which is highly expressed in many types of aggressive cancers including breast and ovarian cancer, has been approved as an ideal target for ADCs. Lidamycin(LDM), developed by Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, is an enediyne-containing antibiotic with potent anti-tumor activity. LDM is a promising payload for ADCs. In the present research, using a special site-directed conjugating technology, we made a novel ADC(607-LDM) with a drug-to-antibody ratio(DAR) of 2 and composed of the anti-HER2 antibody 607 and LDM. The new ADC exhibited potent antitumor activity against human ovarian cancer SKOV3 and breast cancer BT-474 cells. It also induced apoptosis and G2/M arrest.In nude mice with SKOV3 xenografts and a tumor volume of 150-200 mm3, a single intravenous injection 607-LDM at 1 mg·kg-1 induced tumor growth inhibition of 72.4%, which was significant compared to either LDM(50.6%) or antibody(30.2%) treatment alone, or both in combination(50.1%, P < 0.05). All animal experiments were performed in accord with National Regulations and approved by the Animal Experiments Ethical Committee of College of Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences. The novel ADC designed in this study, 607-LDM, is a promising candidate for the treatment of HER2-positive cancers.
Drug use during pregnancy is unavoidable. Therefore, it is vitally important for medical workers to help pregnant women take drugs correctly to reduce the incidence of spontaneous abortion, premature birth, and low birth weight. In our study, drug screening model with induced pluripotent stem cells(iPSCs) was used to find some improper drugs which will result in woman's abortion. With 3D culture in vitro, iPSCs can form embryoid bodies(EBs) and cerebral organoids, which simulated in vitro development of early embryos, from inner cell mass to germ-layer differentiation. In the experiment, EBs were exposed to mifepristone(RU486), and three experimental groups were divided randomly. They were control group(without RU486), low-dose group(L-RU486, 10 μg·mL-1), and high-dose group(H-RU486, 20 μg·mL-1). After mifepristone exposure, EBs were observed at days 5, 8, and 11, including size of EB, cell apoptosis, and differentiation of germ layers, by using inverted optical microscope, TUNEL assay, and immunofluorescent staining. The results showed that through 3D culture, iPSCs could develop into embryoid bodies, neural rosettes, and finally cerebral organoids. After mifepristone exposure, EBs' sizes were decreased(P < 0.01); the levels of cell apoptosis in EBs were increased after mifepristone exposure(P < 0.01); the development of EBs' germ layer was affected. Mifepristone exposure could inhibit the proliferation of embryonic stem cells, reduce the differentiation of ectoderm(P < 0.01) and promote the development of mesoderm(P < 0.05).In conclusion, iPSCs can be used as a screening model for abortion drug, and EBs' diameter, cell apoptosis, and differentiation changes of the germ layers can serve as criteria of abortion drug screening.