Insights into the eradication of drug resistant Staphylococcus aureus via compound 6-nitrobenzo[cd]indole-2(1H)-ketone.

6-Nitrobenzo[cd]indole-2(1H)-ketone (compound C2) exhibits an excellent germicidal effect against methicillin-resistant Staphylococcus aureus (MRSA). Mechanism studies show that C2 induces ROS over-production, cell membrane damage, and ATP and virulence factor down-regulation in bacteria. More importantly, C2 can inhibit biofilm formation and accelerate wound healing in a mouse infection model induced by MRSA.

Targeting Telomerase Enhances Cytotoxicity of Salinomycin in Cancer Cells.

Salinomycin exhibits significant systemic adverse reactions such as tachycardia and myoglobinuria in mammals, which hinders its application as a drug for human cancers. Although many strategies aimed at increasing salinomycin's toxicity to cancer cells have been identified to allow a lower dose of salinomycin to be used, they often cause normal cell damage by themselves. Thus, it is urgent to find more effective methods to increase salinomycin's toxicity to cancer cells with little influences on normal cells. Telomerase, which is expressed highly in most cancer cells rather than normal somatic cells, plays central roles in cancer cell fate regulation. Targeting telomerase represents a potential method for enhancing salinomycin's cytotoxicity to cancer cells with little effects on normal cells. Herein, we improve the toxicity of salinomycin against cancer cells by telomerase inhibition BIBR1532 (BIBR), which binds to the active site of telomerase reverse transcriptase. We find that a non-toxic dose of BIBR can enhance cytotoxicity of salinomycin in MCF-7 and MDA-MB-231 cells. Moreover, BIBR enhances mammosphere formation inhibition mediated by salinomycin in MCF-7 and MDA-MB-231 cells. Further studies show that BIBR enhances tumor growth inhibition induced by salinomycin in vivo. To our knowledge, this is the first example that targeting telomerase improves anti-cancer effects of salinomycin.

A Topologically Engineered Gold Island for Programmed In Vivo Stem Cell Manipulation.

Even a well-designed system can only control stem cell adhesion, release, and differentiation, while other cell manipulations such as in situ labeling and retention in target tissues, are difficult to achieve in the same system. Herein, native ligand cluster-mimicking islands, composed of topologically engineered ligand, anchoring point AuNP, nuclease mimetics CeIV complexes and magnetic core Fe3 O4 , are designed to facilitate comprehensive cell manipulations in a programmable manner. Three islands with different amounts of AuNPs are constructed, which means tunable interligand spacing within a cluster. These nanostructures are chemically coupled to a substrate using DNA tethers. Under a tissue-penetrative magnetic field, this integrated system promotes stem cell adhesion, proliferation, mechanosensing, differentiation, detachment, in situ effective magnetic labeling and retention both in vitro and in vivo, offering fascinating opportunities for a biomimetic matrix in regenerative medicine.

Engineering Amyloid Aggregation as a New Way to Eliminate Cancer Stem Cells by the Disruption of Iron Homeostasis.

Cancer stem cells (CSCs) play crucial roles in tumor initiation. Amyloid ß (Aß), which is associated with Alzheimer's disease (AD), has been identified to induce cytotoxicity in tumor cells besides brain cells. Herein, we find that oligomeric Aß1-42 and Aß1-40 (OAß1-42 and OAß1-40) can repress the viability of breast CSCs. Intriguingly, OAß1-42 and OAß1-40 preferentially induce the growth arrest of breast CSCs by contrast with the bulk cancer cells. Further studies indicate that OAß1-42 and OAß1-40 disturb iron homeostasis, which results in iron accumulation in lysosomes. The iron in lysosomes then induces ROS production by Fenton reaction, leading to breast CSC death. In vivo experiments show that the tumorigenesis of breast CSCs pretreated with OAß1-42 is inhibited. These results reveal that OAß1-42 and OAß1-40 are multifaceted players with the ability to eliminate CSCs. Our work may provide a new clue to better understand the biological functions of amyloid oligomers.

Near-infrared-traceable DNA nano-hydrolase: specific eradication of telomeric G-overhang in vivo.

Telomeric DNA, whose length homeostasis is closely correlated with immortality of cancer cells, is regarded as a molecular clock for cellular lifespan. Regarding the capacity in forming G-quadruplex, G-rich 3'-overhang (G-overhang) has been considered as an attractive anticancer target. However, it is still challenging to precisely target telomeric G-overhang with current ligands because of the polymorphism of G-quadruplexes in cells. Herein, we construct a telomeric G-overhang-specific near-infrared-traceable DNA nano-hydrolase, which is composed of four parts: (i) dexamethasone for targeting cell nuclei; (ii) complementary DNA for hybridizing with G-overhang; (iii) multinuclear Ce(IV) complexes for hydrolyzing G-overhang; and (iv) upconversion nanoparticles for real-time tracking. The multivalent targeted DNA nano-hydrolase can be traced to precisely digest telomeric G-overhang, which contributes to telomeric DNA shortening and thereby causes cell aging and apoptosis. The anticancer treatment is further proved by in vivo studies. In this way, this design provides a telomeric G-overhang-specific eradication strategy based on a non-G-quadruplex targeting manner.

Ethyl-p-methoxycinnamate enhances oct4 expression and reinforces pluripotency through the NF-κB signaling pathway.

Pluripotent stem cells are have therapeutic applications in regenerative medicine and drug discovery. However, the differentiation of stem cells in vitro hinders their large-scale production and clinical applications. The maintenance of cell pluripotency relies on a complex network of transcription factors; of these, octamer-binding transcription factor-4 (Oct4) plays a key role. This study aimed to construct an Oct4 gene promoter-driven firefly luciferase reporter and screen small-molecule compounds could maintain cell self-renewal and pluripotency. The results showed that ethyl-p-methoxycinnamate (EPMC) enhance the promoter activity of the Oct4 gene, increased the expression of Oct4 at both mRNA and protein levels, and significantly promoted the colony formation of P19 cells. These findings suggesting that EPMC could reinforce the self-renewal capacity of P19 cells. The pluripotency markers Oct4, SRY-related high-mobility-group-box protein-2, and Nanog were expressed at higher levels in EPMC-induced colonies. EPMC could promote teratoma formation and differentiation potential of P19 cells in vivo. It also enhanced self-renewal and pluripotency of human umbilical cord mesenchymal stem cells and mouse embryonic stem cells. Moreover, it significantly activated the nuclear factor kappa B (NF-κB) signaling pathway via the myeloid differentiation factor 88-dependent pathway. The expression level of Oct4 decreased after blocking the NF-κB signaling pathway, suggesting that EPMC promoted the expression of Oct4 partially through the NF-κB signaling pathway. This study indicated that EPMC could maintain self-renewal and pluripotency of stem cells.

A Sequential Target-Responsive Nanocarrier with Enhanced Tumor Penetration and Neighboring Effect In Vivo.

Nanodrug-based cancer therapy is impeded by poor penetration into deep tumor tissues mainly due to the overexpression of hyaluronic acid (HA) in the tumor extracellular matrix (ECM). Although modification of nanoparticles (NPs) with hyaluronidase (HAase) is a potent strategy, it remains challenging to get a uniform distribution of drug at the tumor site because of the internalization of NPs by the cells in the tumor and HA regeneration. Herein, an intelligent nanocarrier, which can release HAase in response to the acidic tumor microenvironment (pH 6.5) and perform a strong neighboring effect with size reduction to overcome the above two problems and accomplish drug deep tumor penetration in vivo, is reported. In this design, HAase is encapsulated on the surfaces of doxorubicin (DOX) preloaded ZnO-DOX NPs using a charge convertible polymer PEG-PAH-DMMA (ZDHD). The polymer can release HAase to degrade HA in the tumor ECM (pH 6.5). ZnO-DOX NPs can release DOX in lysosomes (pH 4.5) to induce cell apoptosis, and exert a neighboring effect with size reduction to infect neighboring cells. The hierarchical targeted release of HAase and drugs is demonstrated to enhance tumor penetration and decrease side effects in vivo. This work shows promise for further application of ZDHD NPs in cancer therapy.

20(S)-25-methoxyl-dammarane-3ß,12ß,20-triol attenuates endoplasmic reticulum stress via ERK/MAPK signaling pathway.

Endoplasmic reticulum (ER) stress, together with unfolded protein response (UPR), can remove unfolded proteins and promote survival. However, severe and prolonged ER stress leads to cell death, tissue injury, and many serious diseases. Therefore, it is essential to identify drugs that can attenuate ER stress for ER-related disease treatment. A great deal of research shows that selenoprotein S (SelS) is a sensitive and ideal marker of ER stress. Here, we used a firefly luciferase reporter driven by SelS gene promoter to screen natural compounds that can attenuate ER stress. Then we identified compound 20(S)-25-methoxyl-dammarane-3ß,12ß,20-triol (25-OCH3-PPD) could inhibit the promoter activity of SelS, further results showed that 25-OCH3-PPD effectively inhibited tunicamycin (TM) induced up-regulation of SelS expression in both mRNA and protein levels. Moreover, 25-OCH3-PPD significantly inhibited glucose-regulated protein 78 (GRP78; the major ER stress marker) expression in TM-induced ER stress in HepG2 and HEK293T cells, suggesting that 25-OCH3-PPD could attenuate ER stress in these cells. Mechanism studies showed that 25-OCH3-PPD significantly activated ERK/MAPK signaling pathway, and the inhibition of ERK/MAPK by U0126 dramatically abolished the inhibitory effect of 25-OCH3-PPD on ER stress, suggesting that 25-OCH3-PPD attenuated ER stress at least partially through activation of ERK/MAPK signaling pathway. Taken together, our studies indicate that 25-OCH3-PPD is a novel small molecular compound reducing ER stress, and a potential drug for treating diseases associated with ER stress.

Photocontrolled Multidirectional Differentiation of Mesenchymal Stem Cells on an Upconversion Substrate.

The effective guidance of mesenchymal stem cell (MSC) differentiation on a substrate by near-infrared (NIR) light is particularly attractive for tissue engineering and regenerative medicine. However, most of current substrates cannot control multidirectional differentiation of MSCs like natural tissues. Herein, a photocontrolled upconversion-based substrate was designed and constructed for guiding multidirectional differentiation of MSCs. The substrate enables MSCs to maintain their stem-cell characteristics due to the anti-adhesive effect of 4-(hydroxymethyl)-3-nitrobenzoic acid modified poly(ethylene glycol) (P1) attached on the upconversion substrate. Upon NIR irradiation, the P1 is released from the substrate by photocleavage. The detachment of P1 can change cell-matrix interactions dynamically. Moreover, MSCs cultured on the upconversion substrate can be specifically induced to differentiate to adipocytes or osteoblasts by adjusting the NIR laser. Our work provides a new way of using NIR-based upconversion substrate to modulate the multidirectional differentiation of MSCs.

Graphitic carbon nitride nanosheets as a multifunctional nanoplatform for photochemical internalization-enhanced photodynamic therapy.

Photodynamic therapy (PDT) has been widely used as a noninvasive and moderate technique in precision cancer therapy by destroying cancer cells via light-induced reactive oxygen species (ROS). However, the overproduction of heat shock protein 70 (HSP70) induced by ROS will contribute to the cell survival under harsh conditions, finally leading to decreased PDT efficiency. To overcome this issue, herein, for the first time, we have prepared an HSP70 inhibitor (2-phenylethynesulfonamide (PES))-loaded graphitic carbon nitride nanosheet (GCNS) as a multifunctional nanoplatform (GCNS-PES) for enhanced PDT. By taking advantage of commendable PDT efficiency, strong blue fluorescence, satisfactory drug loading capacity and good water dispersity, the GCNS can simultaneously serve as a photosensitizer, an imaging agent and a drug carrier. Moreover, when the nanoplatform is restricted in the endo/lysosome vesicles through endocytosis, the GCNS can generate ROS effectively under visible light irradiation to promote the lipid peroxidation of endo/lysosomal membranes and accelerate the liberation of GCNS and PES into the cytoplasm. Finally, the tolerance of cancer cells to ROS is decreased by PES-induced HSP70 inactivation, and therefore the efficiency of PDT is significantly enhanced. As a result, GCNS-PES can serve as a promising therapeutic nanoplatform for photo-controlled cancer therapy.

Metallo-supramolecular Complexes Enantioselectively Eradicate Cancer Stem Cells in Vivo.

Cancer stem cells (CSCs) are responsible for drug resistance, metastasis and recurrence of cancers. However, there is still no clinically approved drug that can effectively eradicate CSCs. Thus, it is crucial and important to develop specific CSC-targeting agents. Chiral molecular recognition of DNA plays an important role in rational drug design. Among them, polymorphic telomeric G-quadruplex DNA has received much attention due to its significant roles in telomerase activity and chromosome stability. Herein, we find that one enantiomer of zinc-finger-like chiral metallohelices, [Ni2L3]4+-P, a telomeric G-quadruplex-targeting ligand, can preferentially reduce cell growth in breast CSCs compared to the bulk cancer cells. In contrast, its enantiomer, [Ni2L3]4+-M, has little effect on both populations. Further studies indicate that [Ni2L3]4+-P can repress CSC properties and induce apoptosis in breast CSCs. This is different to the bulk cancer cells. The inhibition of breast CSC traits is involved in the nuclear translocation of hTERT. The apoptosis is associated with the induction of telomere uncapping, telomere DNA damage and the degradation of 3'-overhang. Moreover, [Ni2L3]4+-P, but not [Ni2L3]4+-M, has the ability to reduce tumorigenesis of breast CSCs in vivo. To our knowledge, this is the first report that chiral complexes show significant enantioselectivity on eradicating CSCs.

Metal-Ion-Activated DNAzymes Used for Regulation of Telomerase Activity in Living Cells.

Telomerase is a key regulator in cell metabolism, tissue renewal, and organismal lifespan. Here we develop a simple strategy to modulate cellular telomerase activity, and further control cell fate based on Mg2+ - and Zn2+ -activated DNAzymes in living cells. Through modulation of telomerase activity, we can regulate cell behavior, including cell migration, cell differentiation, cell senescence, and cell cycle. Our work provides a new way to modulate telomerase activity in living cells by using DNAzymes.

Paclitaxel inhibits selenoprotein S expression and attenuates endoplasmic reticulum stress.

The primary effect of the endoplasmic reticulum (ER) stress response or unfolded protein response (UPR) is to reduce the load of unfolded protein and promote survival. However, prolonged and severe ER stress leads to tissue injury and serious diseases. Thus, it is important to identify drugs that can attenuate ER stress for the treatment of diseases. Natural products continue to provide lead compounds for drug discovery and front­line pharmacotherapy for people worldwide. Previous studies have indicated that selenoprotein S (SelS) is a sensitive and ideal maker of ER stress. In the present study, a firefly luciferase reporter driven by the SelS gene promoter was used to screen for natural compounds capable of attenuating ER stress. From this, paclitaxel (PTX) was identified to efficiently inhibit the promoter activity of the SelS gene, and further results revealed that PTX significantly inhibited the tunicamycin­induced upregulation of SelS at the mRNA and protein levels in HepG2 and HEK293T cells. In addition, PTX was able to efficiently inhibit the expression of the ER stress marker, glucose­regulated protein 78, in ER stress, indicating that PTX may reverse ER stress. Taken together, these results suggest that PTX is able to inhibit SelS expression during ER stress and attenuate ER stress.

25-methoxyl-dammarane-3ß, 12ß, 20-triol and artemisinin synergistically inhibit MDA-MB-231 cell proliferation through downregulation of testes-specific protease 50 (TSP50) expression.

While the incidence of cancer continues to increase, the current therapeutic options remain imperfect. Therefore, there is an urgent need to discover new targeted anti-cancer therapies. Testes-specific protease 50 (TSP50) is abnormally expressed in most cancer tissues and downregulation of TSP50 expression can reduce cell proliferation and induce cell apoptosis, which makes it a potential target for cancer therapy. In this study, we constructed a firefly luciferase reporter pGL3-TSP50-3'-UTR as a drug screening model to screen potential candidate compounds that target TSP50 mRNA. We identified the compound 7P3A, which consists of 70 % 25-methoxyl-dammarane-3ß, 12ß, 20-triol and 30 % artemisinin, as being capable of inhibiting the TSP50-3'-UTR reporter activity, as well as the expression of TSP50. Further investigation revealed that 7P3A could inhibit MDA-MB-231 cell proliferation and induce cell cycle arrest, and over-expression of TSP50 partially reversed the effect of 7P3A. In vivo investigation showed that 7P3A could inhibit tumor growth in a xenograft model of breast cancer. These results suggest that 7P3A exhibits anti-cancer effects, in part, through downregulation of TSP50 expression.