New substituted quinoxalines inhibit triple-negative breast cancer by specifically downregulating the c-MYC transcription

Development of a fluorescent ligand that specifically binds to the c-MYC G-quadruplex by migrating the benzene group on a carbazole-benzothiazolium scaffold

c-MYC is one of the most important oncogenes, which is overexpressed in many cancers, and is highly related to development, metastasis, and drug resistance of cancers. The G4 structure in the promoter of c-MYC oncogene contributes a lot to the gene transcriptional mechanism. Small-molecule ligands binding to the c-MYC G4 appear to be a new class of anticancer agents. However, selective ligands for the c-MYC G4 over other G4s have been rarely reported. In this study, we reported a novel fluorescent ligand by migrating the benzene group on a carbazole-benzothiazolium scaffold, which was demonstrated to exhibit considerable specificity to the c-MYC G4, which was distinguished from other small-molecule ligands. The further cellular experiments suggested that this ligand may indeed target the promoter G4 and cause apparent transcriptional inhibition of the c-MYC oncogene instead of other G4-mediated oncogenes, which thereby resulted in cancer cell growth inhibition. Collectively, this study provided a good example for developing specific c-MYC G4 ligands, which may further develop into an effective anticancer agent that inhibit the c-MYC expression.

Harnessing Light for G-Quadruplex Modulation: Dual Isomeric Effects of an Ortho-Fluoroazobenzene Derivative

G-quadruplexes (G4s) are important therapeutic and photopharmacological targets in cancer research. Small-molecule ligands targeting G4s offer a promising strategy to block DNA transactions and induce genetic instability in cancer cells. While numerous G4-ligands have been reported, relatively few examples exist of compounds whose G4-interactive binding properties can be modulated using light. Herein, we report the photophysical characterization of a novel ortho-fluoroazobenzene derivative, Py-Azo4F-3N, that undergoes reversible two-way isomerization upon visible light exposure. Using a combination of biophysical techniques, including affinity and selectivity assays, structural and computational analysis, and cytotoxicity experiments in cancer cell lines, we carefully characterized the G4-interactive binding properties of both isomers. We identify the trans isomer as the most promising form of interacting and stabilizing G4s, enhancing their ablation capability in cancer cells. Our research highlights the importance of light-responsive molecules in achieving precise control over G4 structures, demonstrating their potential in innovative anticancer strategies.

Novel quinoxaline analogs as telomeric G-quadruplex ligands exert antitumor effects related to enhanced immunomodulation

G-quadruplexes (G4s) are commonly formed in the G-rich strand of telomeric DNA. Ligands targeting telomeric G4 induce DNA damage and telomere dysfunction, which makes them potential antitumor drugs. New telomeric G4 ligands with drug-likeness are still needed to be exploited, especially with their antitumor mechanisms thoroughly discussed. In this study, a novel series of quinoxaline analogs were rationally designed and synthesized. Among them, R1 was the most promising ligand for its cytotoxic effects on tumor cells and stabilizing ability with telomeric G4. Cellular assays illustrated that R1 stabilized G4 and induced R-loop accumulation in the telomeric regions, subsequently triggering DNA damage responses, cell cycle arrest in G2/M phase, apoptosis and antiproliferation. Moreover, R1 evoked immunogenic cell death (ICD) in tumor cells, which promoted the maturation of bone marrow derived dendritic cells (BMDCs). In breast cancer mouse model, R1 exhibited a significant decrease in tumor burden through the immunomodulatory effects, including the increase of CD4+ and CD8+ T cells in tumors and cytokine levels in sera. Our research provides a new idea that targeting telomeric G4 induces DNA damage responses, causing antitumor effects both in vitro and in vivo, partially due to the enhancement of immunomodulation.

A Phenotypic Approach to the Discovery of Potent G-Quadruplex Targeted Drugs

G-quadruplex (G4) sequences, which can fold into higher-order G4 structures, are abundant in the human genome and are over-represented in the promoter regions of many genes involved in human cancer initiation, progression, and metastasis. They are plausible targets for G4-binding small molecules, which would, in the case of promoter G4s, result in the transcriptional downregulation of these genes. However, structural information is currently available on only a very small number of G4s and their ligand complexes. This limitation, coupled with the currently restricted information on the G4-containing genes involved in most complex human cancers, has led to the development of a phenotypic-led approach to G4 ligand drug discovery. This approach was illustrated by the discovery of several generations of tri- and tetra-substituted naphthalene diimide (ND) ligands that were found to show potent growth inhibition in pancreatic cancer cell lines and are active in in vivo models for this hard-to-treat disease. The cycles of discovery have culminated in a highly potent tetra-substituted ND derivative, QN-302, which is currently being evaluated in a Phase 1 clinical trial. The major genes whose expression has been down-regulated by QN-302 are presented here: all contain G4 propensity and have been found to be up-regulated in human pancreatic cancer. Some of these genes are also upregulated in other human cancers, supporting the hypothesis that QN-302 is a pan-G4 drug of potential utility beyond pancreatic cancer.

Design and Optimization of Sesamol Nanosuspensions to Potentiate the Anti-Tumor Activity of Epirubicin against Ehrlich Solid Carcinoma-Bearing Mice

There is a growing interest in discovering natural sources of anti-cancer drugs. Sesamol (SES) is a phenolic compound with antitumor effects. The present study aimed to investigate the anticancer properties of SES and its nano-suspensions (SES-NS) combined with Epirubicin (EPI) in breast cancer (BC) using mice bearing a solid Ehrlich tumor. The study involved 35 female albino mice and investigated the effects of SES and EPI on tumor growth, proliferation, apoptosis, autophagy, angiogenesis, and oxidative stress. Methods including ELISA, qRT-PCR, and immunohistochemistry were utilized. The findings revealed reductions in tumor growth and proliferation using SES either alone or combined and evidenced by decreased AKT (AKT Serine/Threonine kinase1) levels, angiogenesis indicated by lower levels of VEGFR (vascular endothelial growth factor), and apoptosis demonstrated by elevated caspase3 and BAX levels. Furthermore, autophagy increased and was indicated by increased levels of beclin1 and lc3, along with decreased oxidative stress as evidenced by elevated TAC (total antioxidant capacity) and reduced MDA (malondialdehyde) levels. Interestingly, SES-NS demonstrated more significant effects at lower doses. In summary, this study underscores the potential of SES as a promising agent for BC treatment. Moreover, SES-NS potentiated the beneficial effects of EPI while mitigating its adverse effects.

Development of a fluorescent ligand that can illuminate nuclear G-quadruplexes and modulate oncogene expression

In this study, we developed a promising dual-function fluorescent ligand termed KS-1 by a slight structural modification on a reported carbazole-based scaffold. KS-1 was then found to mainly bind and illuminate the nuclear DNA G-quadruplexes (G4s) in a sandwich-like interacting mode, and also effectively modulate the oncogene expression through a G4-mediated manner. Furthermore, KS-1 was proved to inhibit cancer cell growth either in 2D monolayer cells or 3D multicellular tumor spheroids. To be noted, this ligand could overcome the shortcomings of other reported dual-function ligands that appeared to accumulate in the lysosomes or mitochondria, and may be used as a theranostic agent in the future.

Constructing triazole-modified quinazoline derivatives as selective c-MYC G-quadruplex ligands and potent anticancer agents through click chemistry

c-MYC is a hallmark of various cancers, playing a critical role in promoting tumorigenesis. The formation of G-quadruplex (G4) in the c-MYC promoter region significantly suppresses its expression. Therefore, developing small-molecule ligands to stabilize c-MYC G4 formation and subsequentially suppress c-MYC expression is an attractive topic for c-MYC-driven cancer therapy. However, achieving selective ligands for c-MYC G4 poses challenges. In this study, we developed a series of triazole-modified quinazoline (TMQ) derivatives as potential c-MYC G4 ligands and c-MYC transcription inhibitors from 4-anilinoquinazoline lead 7a using click chemistry. Importantly, the c-MYC G4 stabilizing ability and antiproliferation activity were well correlated among these new derivatives, particularly in the c-MYC highly expressed colorectal cancer cell line HCT116. Among them, compound A6 exhibited good selectivity in stabilizing c-MYC G4 and in suppressing c-MYC transcription better than 7a. This compound induced G4 formation, selectively inhibited G4-related c-MYC transcription and suppressed the progression of HCT116 cells. These findings identify a new c-MYC transcription inhibitor and provide new insights for optimizing c-MYC G4-targeting ligands.

Discovery of a near-infrared fluorescent probe for G-quadruplexes by exploiting the concept of unfolding-intramolecular-aggregation-induced emission

In the very recent years, the concept of disaggregation-induced emission (DIE) has been applied to design G4 probes, thereby rendering several fluorophores that may suffer from aggregation-induced quenching (ACQ) to develop into desirable G4-selective probes. However, the design idea based on DIE was often limited by the instability and irreversibility of the "intermolecular" aggregation/disaggregation process. In this study, a self-folded, near-infrared fluorescent probe for selectively illuminating G4s was engineered. This probe restored its fluorescence via unfolding of its intramolecular aggregation (UIA) mediated by distinctive G4 binding, which may display more controllable background emission as well as more promising ability to track G4 forming dynamics as compared to the reported DIE probes. Altogether, this study provided insights into the development of new types of applicable G4 selective fluorescent probes.

Discovery of Palbociclib as a potent c-Myc G4 stabilizer for lung cancer treatment using molecular docking, molecular dynamics simulation, and in vitro activity evaluation

Despite significant progress in lung cancer treatment, this disease remains a prevalent and serious global malignancy, leading to high rates of illness and death. Urgent research is needed to discover new or alternative therapies that can improve clinical outcomes for lung cancer patients. In our study, we successfully demonstrated the effectiveness of Palbociclib, a CDK4/6 inhibitor, in suppressing the growth of lung cancer cells. The IC50 values obtained were 11.00 μM and 11.74 μM for H1299 and A549 cells, respectively. Furthermore, our findings indicate that Palbociclib may possess strong c-Myc G4 stabilizing properties by significantly reducing both protein and mRNA expression levels of c-Myc. Additionally, Palbociclib induces apoptosis and causes cell cycle arrest at the G2/M phase in two cells. Through circular dichroism (CD), molecular docking, and molecular dynamics (MD) simulation, we have provided evidence that Palbociclib enhances the structural stability of c-Myc G4 while exhibiting a high binding affinity to its ligand's binding site on c-Myc G4. These results suggest that Palbociclib holds promise as a novel c-Myc G4 stabilizer for treating cancers associated with abnormal c-Myc activity; further optimization and development are warranted.

G-quadruplex ligands as therapeutic agents against cancer, neurological disorders and viral infections

G-quadruplexes (G4s) within the human genome have undergone extensive molecular investigation, with a strong focus on telomeres, gene promoters and repetitive regulatory sequences. G4s play central roles in regulating essential biological processes, including telomere maintenance, replication, transcription and translation. Targeting these molecular processes with G4-binding ligands holds substantial therapeutic potential in anticancer treatments and has also shown promise in treating neurological, skeletal and muscular disorders. The presence of G4s in bacterial and viral genomes also suggests that G4-binding ligands could be a critical tool in fighting infections. This review provides an overview of the progress and applications of G4-binding ligands, their proposed mechanisms of action, challenges faced and prospects for their utilization in anticancer treatments, neurological disorders and antiviral activities.

Moschus ameliorates glutamate-induced cellular damage by regulating autophagy and apoptosis pathway

Alzheimer's disease (AD), a neurodegenerative disorder, causes short-term memory and cognition declines. It is estimated that one in three elderly people die from AD or other dementias. Chinese herbal medicine as a potential drug for treating AD has gained growing interest from many researchers. Moschus, a rare and valuable traditional Chinese animal medicine, was originally documented in Shennong Ben Cao Jing and recognized for its properties of reviving consciousness/resuscitation. Additionally, Moschus has the efficacy of "regulation of menstruation with blood activation, relief of swelling and pain" and is used for treating unconsciousness, stroke, coma, and cerebrovascular diseases. However, it is uncertain whether Moschus has any protective effect on AD patients. We explored whether Moschus could protect glutamate (Glu)-induced PC12 cells from cellular injury and preliminarily explored their related action mechanisms. The chemical compounds of Moschus were analyzed and identified by GC-MS. The Glu-induced differentiated PC12 cell model was thought to be the common AD cellular model. The study aims to preliminarily investigate the intervention effect of Moschus on Glu-induced PC12 cell damage as well as their related action mechanisms. Cell viability, lactate dehydrogenase (LDH), mitochondrial reactive oxygen species, mitochondrial membrane potential (MMP), cell apoptosis, autophagic vacuoles, autolysosomes or autophagosomes, proteins related to apoptosis, and the proteins related to autophagy were examined and analyzed. Seventeen active compounds of the Moschus sample were identified based on GC-MS analysis. In comparison to the control group, Glu stimulation increased cell viability loss, LDH release, mitochondrial damage, loss of MMP, apoptosis rate, and the number of cells containing autophagic vacuoles, and autolysosomes or autophagosomes, while these results were decreased after the pretreatment with Moschus and 3-methyladenine (3-MA). Furthermore, Glu stimulation significantly increased cleaved caspase-3, Beclin1, and LC3II protein expression, and reduced B-cell lymphoma 2/BAX ratio and p62 protein expression, but these results were reversed after pretreatment of Moschus and 3-MA. Moschus has protective activity in Glu-induced PC12 cell injury, and the potential mechanism might involve the regulation of autophagy and apoptosis. Our study may promote research on Moschus in the field of neurodegenerative diseases, and Moschus may be considered as a potential therapeutic agent for AD.

MYC function and regulation in physiological perspective

MYC, a key member of the Myc-proto-oncogene family, is a universal transcription amplifier that regulates almost every physiological process in a cell including cell cycle, proliferation, metabolism, differentiation, and apoptosis. MYC interacts with several cofactors, chromatin modifiers, and regulators to direct gene expression. MYC levels are tightly regulated, and deregulation of MYC has been associated with numerous diseases including cancer. Understanding the comprehensive biology of MYC under physiological conditions is an utmost necessity to demark biological functions of MYC from its pathological functions. Here we review the recent advances in biological mechanisms, functions, and regulation of MYC. We also emphasize the role of MYC as a global transcription amplifier.

Novel c-Myc G4 stabilizer EP12 promotes myeloma cytotoxicity by disturbing NF-κB signaling

Multiple myeloma (MM) is a B-cell malignancy characterized by the excessive proliferation of bone marrow plasma cells and the production of abnormal immunoglobulins. Despite advances in therapeutic strategies, it remains an incurable disease. Recently, innovative anticancer drugs have been developed and approved, leading to improvements in MM therapy; however, drug resistance continues to be a major obstacle that results in treatment failure. Therefore, the development of novel agents is imperative to achieve superior therapeutic outcomes for relapsed/refractory multiple myeloma (MM) patients. Previously, we identified EP12 as a c-Myc G4 stabilizer that could induce cytotoxicity in MM cells in vitro. However, further investigation is required to elucidate the underlying molecular mechanisms and anti-MM activity of EP12 in vivo. In this study, we have discovered that the compound EP12 effectively inhibits primary myeloma growth in vivo by destabilizing c-Myc and disrupting the canonical nuclear factor-κB (NF-κB) signaling pathway. Overall, our findings suggest that EP12, as a potent c-Myc inhibitor, holds great promise as a therapeutic agent for MM.

Non-fused imidazole-biphenyl analogs repress triple-negative breast cancer growth by mainly stabilizing the c-MYC G-quadruplex via a multi-site binding mode

As oncogene c-MYC is abnormally expressed during TNBC pathogenesis, stabilizing its promoter G-quadruplex (G4), which may thus inhibit c-MYC expression and promote DNA damage, may be a potential anti-TNBC strategy. However, large quantities of potential G4-forming sites exist in the human genome, which represents a potential drug selectivity problem. In order to achieve better recognition for c-MYC G4, we herein presented a new approach of designing small-molecule ligands by linking tandem aromatic rings with the c-MYC G4 selective binding motifs. Thus, a series of non-fused, conformation-tunable imidazole-biphenyl analogs were designed and synthesized. Among them, the optimal ligand appeared more effective on stabilizing c-MYC G4 than other types of G4s possibly through an adaptive, multi-site binding mode involved of end-stacking, groove-binding and loop-interacting. Then, the optimal ligand exerted good inhibitory activity on c-MYC expression and induced remarkable DNA damage, leading to the occurrence of G2/M phase arrest, apoptosis and autophagy. Furthermore, the optimal ligand exhibited potent antitumor effects in a TNBC xenograft tumor model. To sum up, this work offers new insights for the development of selective c-MYC G4 ligands against TNBC.

New triazole-attached quinoxalines selectively recognize the telomeric multimeric G-quadruplexes and inhibit breast cancer cell growth

The telomeric 3'-overhang had potential to form into higher-order structures termed multimeric G-quadruplexes (G4s), which may mainly exist in telomeres, representing an attractive drug target for development of anticancer agents with few side effects. However, only a few molecules that selectively bind to multimeric G4s have been found by random screening, which means a lot of room for improvement. In this study, we raised a feasible strategy to design small-molecule ligands with possible selectivity to multimeric G4s, and then synthesized a focused library of multi-aryl compounds by attaching triazole rings to the quinoxaline skeleton. Among them, QTR-3 was identified as the most promising selective ligand that may bind at the G4-G4 interface, which accordingly stabilized multimeric G4s and induced DNA damage in telomeric region, thereby leading to cell cycle arrest and apoptosis. Notably, QTR-3 showed more significant inhibition on breast cancer cells against normal mammary cells.

G-Quadruplexes in c-MYC Promoter as Targets for Cancer Therapy

Cancer is a societal burden demanding innovative approaches. A major problem with the conventional chemotherapeutic agents is their strong toxicity and other side effects due to their poor selectivity. Uncontrolled proliferation of cancer cells is due to mutations, deletions, or amplifications in genes (oncogenes) encoding for proteins that regulate cell growth and division, such as transcription factors, for example, c-MYC. The direct targeting of the c-MYC protein has been attempted but so far unsuccessfully, as it lacks a definite binding site for the modulators. Meanwhile, another approach has been explored since the discovery that G-quadruplex secondary DNA structures formed in the guanine-rich sequences of the c-MYC promoter region can downregulate the transcription of this oncogene. Here, we will overview the major achievements made in the last decades towards the discovery of a new class of anticancer drugs targeting G-quadruplexes in the c-MYC promoter of cancer cells.

Moschus exerted protective activity against H2O2-induced cell injury in PC12 cells through regulating Nrf-2/ARE signaling pathways

The pivotal characteristics of Alzheimer's disease (AD) are irreversible memory loss and progressive cognitive decline, eventually causing death from brain failure. In the various proposed hypotheses of AD, oxidative stress is also regarded as a symbolic pathophysiologic cascade contributing to brain diseases. Using Chinese herbal medicine may be beneficial for treating and preventing AD. As a rare and valuable animal medicine, Moschus possesses antioxidant and antiapoptotic efficacy and is extensively applied for treating unconsciousness, stroke, coma, and cerebrovascular diseases. We aim to evaluate whether Moschus protects PC12 cells from hydrogen peroxide (H₂O₂)-induced cellular injury. The chemical constituents of Moschus are analyzed by GC-MS assay. The cell viability, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP) levels, oxidative stress-related indicators, and apoptotic proteins are determined. Through GC-MS analysis, nineteen active contents were identified. The cell viability loss, lactate dehydrogenase releases, MMP levels, ROS productions, and Malondialdehyde (MDA) activities decreased, and BAX, Caspase-3, and Kelch-like ECH-associated protein 1 expression also significantly down-regulated and heme oxygenase 1, nuclear factor erythroid-2-related factor 2 (Nrf-2), and quinine oxidoreductase 1 expression upregulated after pretreatment of Moschus. The result indicated Moschus has neuroprotective activity in relieving H₂O₂-induced cellular damage, and the potential mechanism might be associated with regulating the Nrf-2/ARE signaling pathway. A more in-depth and comprehensive understanding of Moschus in the pathogenesis of AD will provide a fundamental basis for in vivo AD animal model research, which may be able to provide further insights and new targets for AD therapy.

Expanding the Toolbox of Target Directed Bio-Orthogonal Synthesis: In Situ Direct Macrocyclization by DNA Templates

Herein, we demonstrate for the first time that noncanonical DNA can direct macrocyclization-like challenging reactions to synthesize gene modulators. The planar G-quartets present in DNA G-quadruplexes (G4s) provide a size complementary reaction platform for the bio-orthogonal macrocyclization of bifunctional azide and alkyne fragments over oligo- and polymerization. G4s immobilized on gold-coated magnetic nanoparticles have been used as target templates to enable easy identification of a selective peptidomimetic macrocycle. Structurally similar macrocycles have been synthesized to understand their functional role in the modulation of gene function. The innate fluorescence of the in situ formed macrocycle has been utilized to monitor its cellular localization using a G4 antibody and its in cell formation from the corresponding azide and alkyne fragments. The successful execution of in situ macrocyclization in vitro and in cells would open up a new dimension for target-directed therapeutic applications.

10-Gingerol Enhances the Effect of Taxol in Triple-Negative Breast Cancer via Targeting ADRB2 Signaling

Purpose

Although paclitaxel is widely used in cancer treatment, severe side effects and drug resistance limit its clinical use. 10-gingerol (10-G) is a natural compound isolated from ginger, which displays anti-inflammatory, antioxidant, and antiproliferative properties. However, the chemotherapy-sensitization effect of 10-G on triple-negative breast cancer (TNBC) has not been fully clarified. This study is aimed at investigating the effect of 10-G on the paclitaxel sensitivity in TNBC, and its underlying mechanism.

Methods

The study was determined through in vitro and in vivo experiments. Cell viability and proliferation were detected by cell counting kit 8 (CCK-8) and colony formation. To detect cell apoptosis, flow cytometry and TUNEL were used. The expression of proteins was detected by Western blotting and immunohistochemistry. The molecular docking and gene knockout were corroborated by interactions between 10-G and adrenoceptor Beta 2 (ADRB2). The body weight of mice, histopathology and organs (kidney and spleen) coefficients were used to monitor the drug toxicities.

Results

In vitro, 10-G increased the sensitivity of TNBC cells to paclitaxel, and could synergistically promote the apoptosis of TNBC cells induced by paclitaxel. In combination with molecular docking and lentivirus knockdown studies, ADRB2 was identified as a 10-G binding protein. 10-G inhibited ADRB2 by binding to the active site of ADRB2. Knockdown of ADRB2 reduces the proliferation activity of TNBC cells but also attenuates the sensitizing effects of 10-G to paclitaxel. Western blotting and immunohistochemistry showed that 10-G played an anti-proliferation and chemotherapy-sensitizing role by inhibiting the ADRB2/ERK signal. Toxicity evaluation showed that 10-G would not increase hepatorenal toxicity with paclitaxel.

Conclusion

This data suggests that 10-G may be used as a new chemotherapeutic synergist in combination with paclitaxel to enhance anticancer activity. The potential value of ADRB2 as a target for improving chemotherapy sensitivity was also emphasized.

Crosstalk between G-quadruplex and ROS

The excessive production of reactive oxygen species (ROS) can lead to single nucleic acid base damage, DNA strand breakage, inter- and intra-strand cross-linking of nucleic acids, and protein-DNA cross-linking involved in the pathogenesis of cancer, neurodegenerative diseases, and aging. G-quadruplex (G4) is a stacked nucleic acid structure that is ubiquitous across regulatory regions of multiple genes. Abnormal formation and destruction of G4s due to multiple factors, including cations, helicases, transcription factors (TFs), G4-binding proteins, and epigenetic modifications, affect gene replication, transcription, translation, and epigenetic regulation. Due to the lower redox potential of G-rich sequences and unique structural characteristics, G4s are highly susceptible to oxidative damage. Additionally, the formation, stability, and biological regulatory role of G4s are affected by ROS. G4s are involved in regulating gene transcription, translation, and telomere length maintenance, and are therefore key players in age-related degeneration. Furthermore, G4s also mediate the antioxidant process by forming stress granules and activating Nrf2, which is suggestive of their involvement in developing ROS-related diseases. In this review, we have summarized the crosstalk between ROS and G4s, and the possible regulatory mechanisms through which G4s play roles in aging and age-related diseases.

Recent advances of bioactive proteins/polypeptides in the treatment of breast cancer

Proteins do not only serve as nutrients to fulfill the demand for food, but also are used as a source of bioactive proteins/polypeptides for regulating physical functions and promoting physical health. Female breast cancer has the highest incidence in the world and is a serious threat to women's health. Bioactive proteins/polypeptides exert strong anti-tumor effects and exhibit inhibition of multiple breast cancer cells. This review discussed the suppressing effects of bioactive proteins/polypeptides on breast cancer in vitro and in vivo, and their mechanisms of migration and invasion inhibition, apoptosis induction, and cell cycle arrest. This may contribute to providing a basis for the development of bioactive proteins/polypeptides for the treatment of breast cancer.

Graphical abstract

Strategies to target the cancer driver MYC in tumor cells

The MYC oncoprotein functions as a master regulator of cellular transcription and executes non-transcriptional tasks relevant to DNA replication and cell cycle regulation, thereby interacting with multiple proteins. MYC is required for fundamental cellular processes triggering proliferation, growth, differentiation, or apoptosis and also represents a major cancer driver being aberrantly activated in most human tumors. Due to its non-enzymatic biochemical functions and largely unstructured surface, MYC has remained difficult for specific inhibitor compounds to directly address, and consequently, alternative approaches leading to indirect MYC inhibition have evolved. Nowadays, multiple organic compounds, nucleic acids, or peptides specifically interfering with MYC activities are in preclinical or early-stage clinical studies, but none of them have been approved so far for the pharmacological treatment of cancer patients. In addition, specific and efficient delivery technologies to deliver MYC-inhibiting agents into MYC-dependent tumor cells are just beginning to emerge. In this review, an overview of direct and indirect MYC-inhibiting agents and their modes of MYC inhibition is given. Furthermore, we summarize current possibilities to deliver appropriate drugs into cancer cells containing derailed MYC using viral vectors or appropriate nanoparticles. Finding the right formulation to target MYC-dependent cancers and to achieve a high intracellular concentration of compounds blocking or attenuating oncogenic MYC activities could be as important as the development of novel MYC-inhibiting principles.

Dual Targeting Topoisomerase/G-Quadruplex Agents in Cancer Therapy-An Overview

Topoisomerase (Topo) inhibitors have long been known as clinically effective drugs, while G-quadruplex (G4)-targeting compounds are emerging as a promising new strategy to target tumor cells and could support personalized treatment approaches in the near future. G-quadruplex (G4) is a secondary four-stranded DNA helical structure constituted of guanine-rich nucleic acids, and its stabilization impairs telomere replication, triggering the activation of several protein factors at telomere levels, including Topos. Thus, the pharmacological intervention through the simultaneous G4 stabilization and Topos inhibition offers a new opportunity to achieve greater antiproliferative activity and circumvent cellular insensitivity and resistance. In this line, dual ligands targeting both Topos and G4 emerge as innovative, efficient agents in cancer therapy. Although the research in this field is still limited, to date, some chemotypes have been identified, showing this dual activity and an interesting pharmacological profile. This paper reviews the available literature on dual Topo inhibitors/G4 stabilizing agents, with particular attention to the structure-activity relationship studies correlating the dual activity with the cytotoxic activity.

Matrine, a potential c-Myc inhibitor, suppresses ribosome biogenesis and nucleotide metabolism in myeloid leukemia

Previous studies have shown that matrine, a natural compound extracted from the herb Sophora flavescens, has a good anti-leukemia effect, but its key target and mechanism remains unclear. Here, we found that only c-Myc could respond rapidly to matrine treatment in three myeloid leukemia cell lines, and matrine inhibited both transcription and translation of c-Myc. Ribosome biogenesis and nucleotide metabolism, the key downstream of c-Myc, were significantly suppressed after matrine treatment. Therefore, our results confirmed that matrine is a special c-Myc inhibitor which suppresses ribosome biogenesis and nucleotide metabolism by inhibiting c-Myc in myeloid leukemia. This study provides scientific basis for the development of matrine derivatives to c-Myc-driven cancers.

Crosstalk between Hypoxia and Extracellular Matrix in the Tumor Microenvironment in Breast Cancer

Even though breast cancer is the most diagnosed cancer among women, treatments are not always successful in preventing its progression. Recent studies suggest that hypoxia and the extracellular matrix (ECM) are important in altering cell metabolism and tumor metastasis. Therefore, the aim of this review is to study the crosstalk between hypoxia and the ECM and to assess their impact on breast cancer progression. The findings indicate that hypoxic signaling engages multiple mechanisms that directly contribute to ECM remodeling, ultimately increasing breast cancer aggressiveness. Second, hypoxia and the ECM cooperate to alter different aspects of cell metabolism. They mutually enhance aerobic glycolysis through upregulation of glucose transport, glycolytic enzymes, and by regulating intracellular pH. Both alter lipid and amino acid metabolism by stimulating lipid and amino acid uptake and synthesis, thereby providing the tumor with additional energy for growth and metastasis. Third, YAP/TAZ signaling is not merely regulated by the tumor microenvironment and cell metabolism, but it also regulates it primarily through its target c-Myc. Taken together, this review provides a better understanding of the crosstalk between hypoxia and the ECM in breast cancer. Additionally, it points to a role for the YAP/TAZ mechanotransduction pathway as an important link between hypoxia and the ECM in the tumor microenvironment, driving breast cancer progression.

Discovery of a Novel G-Quadruplex and Histone Deacetylase (HDAC) Dual-Targeting Agent for the Treatment of Triple-Negative Breast Cancer

The development of triple-negative breast cancer (TNBC) is highly associated with G-quadruplex (G4); thus, targeting G4 is a potential strategy for TNBC therapy. Because concomitant histone deacetylases (HDAC) inhibition could amplify the impact of G4-targeting compounds, we designed and synthesized two novel series of G4/HDAC dual-targeting compounds by connecting the zinc-binding pharmacophore of HDAC inhibitors to the G4-targeting isaindigotone scaffold (1). Among the new compounds, a6 with the potent HDAC inhibitory and G4 stabilizing activity could induce more DNA G4 formation than SAHA and 1 in TNBC cells. Remarkably, a6 caused more G4-related DNA damage and G4-related differentially expressed genes, consistent with its effect on disrupting the cell cycle, invasion, and glycolysis. Furthermore, a6 significantly suppresses the proliferation of various TNBC cells and the MDA-MB-231 xenograft model without evident toxicity. Our study suggests a novel strategy for TNBC therapeutics through dual-targeting HDAC and G4.

Interaction between non-coding RNAs, mRNAs and G-quadruplexes

G-quadruplexes are secondary helical configurations established between guanine-rich nucleic acids. The structure is seen in the promoter regions of numerous genes under certain situations. Predicted G-quadruplex-forming sequences are distributed across the genome in a non-random way. These structures are formed in telomeric regions of the human genome and oncogenic promoter G-rich regions. Identification of mechanisms of regulation of stability of G-quadruplexes has practical significance for understanding the molecular basis of genetic diseases such as cancer. A number of non-coding RNAs such as H19, XIST, FLJ39051 (GSEC), BC200 (BCYRN1), TERRA, pre-miRNA-1229, pre-miRNA-149 and miR-1587 have been found to contain G-quadraplex-forming regions or affect configuration of these structures in target genes. In the current review, we outline the recent research on the interaction between G-quadruplexes and non-coding RNAs, other RNA transcripts and DNA molecules.

Development of a Smart Fluorescent Probe Specifically Interacting with C-Myc I-Motif

I-motifs play key regulatory roles in biological processes, holding great potential as attractive therapeutic targets. In the present study, we developed a novel fluorescent probe G59 with strong and selective binding to the c-myc gene promoter i-motif. G59 had an i-motif-binding carbazole moiety conjugated with naphthalimide fluorescent groups. G59 could differentiate the c-myc i-motif from other DNA structures through selective activation of its fluorescence, with its apparent visualization in solution. The smart probe G59 showed excellent sensitivity, with a low fluorescent detection limit of 154 nM and effective stabilization to the c-myc i-motif. G59 could serve as a rapid and sensitive probe for label-free screening of selective c-myc i-motif binding ligands under neutral crowding conditions. To the best of our knowledge, G59 is the first fluorescent probe with high sensitivity for recognizing the i-motif structure and screening for selective binding ligands.

Discovery of a fluorescent, long chain-bridged bispurine that selectively targets the c-MYC G-quadruplex

G-quadruplexes (G4s) are special nucleic acid structures which are involved in the regulation of some key biological events like transcription and translation, which are now treated as promising therapeutic targets for cancers. Stabilizing the promoter G4 by small-molecule ligands can suppress the c-MYC oncogene transcription, thus inhibiting cancer cell proliferation. So far, targeting the very structure, a number of ligands have been reported. However, most of them showed unsatisfactory specificity to the c-MYC G4 over other G4s, resulting in uncertain side effects. In this contribution, we discovered a new class of bispurines bridged with flexible hydrocarbon chains, which presented somewhat selectivity to the c-MYC G4 possibly by adaptive binding, which then showed clear inhibition on the c-MYC expression rather than other G4-driven oncogenes. Moreover, these novel molecules had the potential to fluorescently label G4s. We believed that this study may shed light on the discovery of new functional small molecules targeting a specific G4 structure.

Major Achievements in the Design of Quadruplex-Interactive Small Molecules

Organic small molecules that can recognize and bind to G-quadruplex and i-Motif nucleic acids have great potential as selective drugs or as tools in drug target discovery programs, or even in the development of nanodevices for medical diagnosis. Hundreds of quadruplex-interactive small molecules have been reported, and the challenges in their design vary with the intended application. Herein, we survey the major achievements on the therapeutic potential of such quadruplex ligands, their mode of binding, effects upon interaction with quadruplexes, and consider the opportunities and challenges for their exploitation in drug discovery.

G-Quadruplex Matters in Tissue-Specific Tumorigenesis by BRCA1 Deficiency

How and why distinct genetic alterations, such as BRCA1 mutation, promote tumorigenesis in certain tissues, but not others, remain an important issue in cancer research. The underlying mechanisms may reveal tissue-specific therapeutic vulnerabilities. Although the roles of BRCA1, such as DNA damage repair and stalled fork stabilization, obviously contribute to tumor suppression, these ubiquitously important functions cannot explain tissue-specific tumorigenesis by BRCA1 mutations. Recent advances in our understanding of the cancer genome and fundamental cellular processes on DNA, such as transcription and DNA replication, have provided new insights regarding BRCA1-associated tumorigenesis, suggesting that G-quadruplex (G4) plays a critical role. In this review, we summarize the importance of G4 structures in mutagenesis of the cancer genome and cell type-specific gene regulation, and discuss a recently revealed molecular mechanism of G4/base excision repair (BER)-mediated transcriptional activation. The latter adequately explains the correlation between the accumulation of unresolved transcriptional regulatory G4s and multi-level genomic alterations observed in BRCA1-associated tumors. In summary, tissue-specific tumorigenesis by BRCA1 deficiency can be explained by cell type-specific levels of transcriptional regulatory G4s and the role of BRCA1 in resolving it. This mechanism would provide an integrated understanding of the initiation and development of BRCA1-associated tumors.

Are Transcription Factors Plausible Oncotargets for Triple Negative Breast Cancers?

Simple Summary

Triple negative breast cancer is a type of breast cancer that does not have a selective and effective therapy. It is known that this cancer possesses high abundance of certain proteins called transcription factors, which are essential for their growth. However, inhibiting transcription factors is very difficult with common therapeutics due to their inaccessibility inside the cell and their molecular structure. In this work, we identified the most important transcription factors for the growth of triple negative breast cancers, and that can predict worse clinical outcome. Moreover, we described different strategies that have been utilised to inhibit them. A successful inhibition of these transcription factors could reduce the mortality and convalescence associated with triple negative breast cancers.

Abstract

Breast cancer (BC) is the most diagnosed cancer worldwide and one of the main causes of cancer deaths. BC is a heterogeneous disease composed of different BC intrinsic subtypes such as triple-negative BC (TNBC), which is one of the most aggressive subtypes and which lacks a targeted therapy. Recent comprehensive analyses across cell types and cancer types have outlined a vast network of protein–protein associations between transcription factors (TFs). Not surprisingly, protein–protein networks central to oncogenesis and disease progression are highly altered during TNBC pathogenesis and are responsible for the activation of oncogenic programs, such as uncontrollable proliferation, epithelial-to-mesenchymal transition (EMT) and stemness. From the therapeutic viewpoint, inhibiting the interactions between TFs represents a very significant challenge, as the contact surfaces of TFs are relatively large and featureless. However, promising tools have emerged to offer a solution to the targeting problem. At the clinical level, some TF possess diagnostic and prognostic value in TNBC. In this review, we outline the recent advances in TFs relevant to TNBC growth and progression. Moreover, we highlight different targeting approaches to inhibit these TFs. Furthermore, the validity of such TFs as clinical biomarkers has been explored. Finally, we discuss how research is likely to evolve in the field.

Modulating gene expression in breast cancer via DNA secondary structure and the CRISPR toolbox

Breast cancer is the most commonly diagnosed malignancy in women, and while the survival prognosis of patients with early-stage, non-metastatic disease is ∼75%, recurrence poses a significant risk and advanced and/or metastatic breast cancer is incurable. A distinctive feature of advanced breast cancer is an unstable genome and altered gene expression patterns that result in disease heterogeneity. Transcription factors represent a unique therapeutic opportunity in breast cancer, since they are known regulators of gene expression, including gene expression involved in differentiation and cell death, which are themselves often mutated or dysregulated in cancer. While transcription factors have traditionally been viewed as 'undruggable', progress has been made in the development of small-molecule therapeutics to target relevant protein-protein, protein-DNA and enzymatic active sites, with varying levels of success. However, non-traditional approaches such as epigenetic editing, transcriptional control via CRISPR/dCas9 systems, and gene regulation through non-canonical nucleic acid secondary structures represent new directions yet to be fully explored. Here, we discuss these new approaches and current limitations in light of new therapeutic opportunities for breast cancers.

Quinoxaline Derivatives as a Promising Scaffold for Breast Cancer Treatment

According to Global Cancer Statistics 2021, female breast cancer has exceeded lung cancer as the most frequently diagnosed cancer. As a result of this widespread breast cancer, it was necessary...

DSTYK Enhances Chemoresistance in Triple-Negative Breast Cancer Cells

Breast cancer, as the most prevalent cancer in women, is responsible for more than 15% of new cancer cases and about 6.9% of all cancer-related death in the US. A major cause of therapeutic failure in breast cancer is the development of resistance to chemotherapy, especially for triple-negative breast cancer (TNBC). Therefore, how to overcome chemoresistance is the major challenge to improve the life expectancy of breast cancer patients. Our studies demonstrate that TNBC cells surviving the chronic treatment of chemotherapeutic drugs show significantly higher expression of the dual serine/threonine and tyrosine protein kinase (DSTYK) than non-treated parental cells. In our in vitro cellular models, DSTYK knockout via the CRISPR/Cas9-mediated technique results in apoptotic cell death of chemoresistant cells upon drug treatment. Moreover, DSTYK knockout promotes chemotherapeutic drug-induced tumor cell death in an orthotopic mouse model. These findings suggest that DSTYK exerts an important and previously unknown role in promoting chemoresistance. Our studies provide fundamental insight into the role of DSTYK in chemoresistance in TNBC cells and lay the foundation for the development of new strategies targeting DSTYK for improving TNBC therapy.

Ginsenoside Compound K Assisted G-Quadruplex Folding and Regulated G-Quadruplex-Containing Transcription

Ginsenoside compound K (CK) is one of the major metabolites of the bioactive ingredients in Panax ginseng, which presents excellent bioactivity and regulates the expression of important proteins. In this work, the effects of CK on G-quadruplexes (G4s) were quantitatively analyzed in the presence and absence of their complementary sequences. CK was demonstrated to facilitate the formation of G4s, and increase the quantity of G4s in the competition with duplex. Thermodynamic experiments suggested that the electrostatic interactions were important for G4 stabilization by CK. CK was further found to regulate the transcription of G4-containing templates, reduce full-length transcripts, and decrease the transcription efficiency. Our results provide new evidence for the pharmacological study of ginsenosides at the gene level.

Selective Recognition of a Single HIV-1 G-Quadruplex by Ultrafast Small-Molecule Screening

G-quadruplexes (G4s) are implicated in pathological processes such as cancer and infective diseases. Their targeting with G4-ligands has shown therapeutic capacity. Most of the current G4-ligands are planar molecules, do not discriminate among G4s, and have poor druglike properties. The available methods to identify compounds selective for one single G4 are often time-consuming. Here, we describe the development, validation, and application of an affinity-selection mass spectrometry method that employs unlabeled G4 oligonucleotides as targets and allows testing of up to 320 unmodified small molecules in a single tube. As a proof of concept, this method was applied to screen a library of 40 000 druglike molecules against two G4s, transcriptional regulators of the HIV-1 LTR promoter. We identified nonplanar pyrazolopyrimidines that selectively recognize and stabilize the major HIV-1 LTR G4 possibly by fitting and binding through H-bonding in its unique binding pocket. The compounds inhibit LTR promoter activity and HIV-1 replication. We propose this method to prompt the fast development of new G4-based therapeutics.

Association between systemic immune-inflammation index and neoadjuvant chemotherapy efficacy as well as prognosis in triple-negative breast cancer

OBJECTIVES

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer with a relatively poor prognosis. Neoadjuvant chemotherapy (NAC) is the main treatment method. Due to the heterogeneity of the tumor, the chemotherapy response of TNBC patients is significantly different. Inflammation is closely related to the occurrence and development of cancer. The systemic immune-inflammation index (SII) is an indicator that can comprehensively reflect the state of systemic inflammation. This study aims to explore the association between SII and the NAC efficacy as well as the prognosis in TNBC.

METHODS

The data of TNBC patients who underwent NAC and systemic treatment in Xiangya Hospital of Central South University from January 2015 to June 2019 were collected. According to the inclusion and exclusion criteria, 231 TNBC patients were finally included. The pre-NAC SII was calculated according to the blood routine results of the patients at 1 week before chemotherapy, and the patients were divided into a pre-NAC low SII group (SII<412, 115 cases) and a pre-NAC high SII group (SII≥412, 116 cases). The SII after chemotherapy was calculated according to the blood routine results of the patients at 2 to 3 months after the end of chemotherapy, and the patients were divided into a low SII group after chemotherapy (SII<474, 115 cases) and a high SII group after chemotherapy (SII≥474, 116 cases). Pearson's chi-square test was used to analyze the relationship between SII and other clinical characteristics of TNBC patients, and the relationship between the NAC efficacy and clinical characteristics of TNBC patients. Binary logistic regression analysis was used to find independent factors that affect the efficacy of NAC in TNBC patients. Kaplan-Meier curve analysis was used to analyze factors affecting the prognosis of TNBC patients. Cox regression model was used to find independent factors affecting the prognosis of TNBC patients.

RESULTS

Before NAC, the differences in SII between groups with different ages and tumor sizes were significant (P=0.007 and P=0.002, respectively); after chemotherapy, there were no significant differences in SII between different ages, tumor sizes, histological grades, lymph node staging, and Ki-67 groups (all P>0.05). There were 115 patients with low SII before NAC, with a pathological complete response (pCR) rate of 15.7%; there were 116 patients with high SII before NAC, with a pCR rate of 6.0%. Patients with low SII before NAC had a higher pCR rate than patients with high SII before NAC, and the difference was statistically significant (P=0.019).There were 156 patients with lymph node staging pN0, with a pCR rate of 14.7%; and there were 75 patients with lymph node staging pN1-pN2, with a pCR rate of 2.7%. Patients with lymph node staging pN0 had a higher pCR rate than those with lymph node staging pN1-pN2, and the difference was significant (P=0.006). During the follow-up, 34 patients had local recurrence or distant metastasis. The Kaplan-Meier survival curve showed that the 3-year disease-free survival (DFS) rates for patients with low SII before NAC and high SII before NAC were 87.8% and 82.8%, respectively, and the former was significantly higher than the latter (P=0.005); the 3-year DFS rates for patients with tumor sizes of T1-T2 and T3 were 89.0% and 67.5%, respectively, and the former was significantly higher than the latter (P=0.001); the 3-year DFS rates for patients with lymph node staging of pN0 and pN1-pN2 were 87.8% and 82.8%, respectively, and the former was significantly higher than the latter (P=0.009). Cox analysis showed that SII before NAC and tumor size were independent influencing factors of patients' DFS (P=0.038, P=0.010, respectively).

CONCLUSIONS

SII has important clinical significance in predicting the efficacy and prognosis of NAC in TNBC patients, and it has the potential to be a biomarker.

G-quadruplex DNA: a novel target for drug design

G-quadruplex (G4) DNA is a type of quadruple helix structure formed by a continuous guanine-rich DNA sequence. Emerging evidence in recent years authenticated that G4 DNA structures exist both in cell-free and cellular systems, and function in different diseases, especially in various cancers, aging, neurological diseases, and have been considered novel promising targets for drug design. In this review, we summarize the detection method and the structure of G4, highlighting some non-canonical G4 DNA structures, such as G4 with a bulge, a vacancy, or a hairpin. Subsequently, the functions of G4 DNA in physiological processes are discussed, especially their regulation of DNA replication, transcription of disease-related genes (c-MYC, BCL-2, KRAS, c-KIT et al.), telomere maintenance, and epigenetic regulation. Typical G4 ligands that target promoters and telomeres for drug design are also reviewed, including ellipticine derivatives, quinoxaline analogs, telomestatin analogs, berberine derivatives, and CX-5461, which is currently in advanced phase I/II clinical trials for patients with hematologic cancer and BRCA1/2-deficient tumors. Furthermore, since the long-term stable existence of G4 DNA structures could result in genomic instability, we summarized the G4 unfolding mechanisms emerged recently by multiple G4-specific DNA helicases, such as Pif1, RecQ family helicases, FANCJ, and DHX36. This review aims to present a general overview of the field of G-quadruplex DNA that has progressed in recent years and provides potential strategies for drug design and disease treatment.

A Minimalistic Coumarin Turn-On Probe for Selective Recognition of Parallel G-Quadruplex DNA Structures

G-quadruplex (G4) DNA structures are widespread in the human genome and are implicated in biologically important processes such as telomere maintenance, gene regulation, and DNA replication. Guanine-rich sequences with potential to form G4 structures are prevalent in the promoter regions of oncogenes, and G4 sites are now considered as attractive targets for anticancer therapies. However, there are very few reports of small “druglike” optical G4 reporters that are easily accessible through one-step synthesis and that are capable of discriminating between different G4 topologies. Here, we present a small water-soluble light-up fluorescent probe that features a minimalistic amidinocoumarin-based molecular scaffold that selectively targets parallel G4 structures over antiparallel and non-G4 structures. We showed that this biocompatible ligand is able to selectively stabilize the G4 template resulting in slower DNA synthesis. By tracking individual DNA molecules, we demonstrated that the G4-stabilizing ligand perturbs DNA replication in cancer cells, resulting in decreased cell viability. Moreover, the fast-cellular entry of the probe enabled detection of nucleolar G4 structures in living cells. Finally, insights gained from the structure–activity relationships of the probe suggest the basis for the recognition of parallel G4s, opening up new avenues for the design of new biocompatible G4-specific small molecules for G4-driven theranostic applications.

Quadruplex Ligands in Cancer Therapy

Nucleic acids can adopt alternative secondary conformations including four-stranded structures known as quadruplexes. To date, quadruplexes have been demonstrated to exist both in human chromatin DNA and RNA. In particular, quadruplexes are found in guanine-rich sequences constituting G-quadruplexes, and in cytosine-rich sequences forming i-Motifs as a counterpart. Quadruplexes are associated with key biological processes ranging from transcription and translation of several oncogenes and tumor suppressors to telomeres maintenance and genome instability. In this context, quadruplexes have prompted investigations on their possible role in cancer biology and the evaluation of small-molecule ligands as potential therapeutic agents. This review aims to provide an updated close-up view of the literature on quadruplex ligands in cancer therapy, by grouping together ligands for DNA and RNA G-quadruplexes and DNA i-Motifs.

Selectivity and Targeting of G-Quadruplex Binders Activated by Adaptive Binding and Controlled by Chemical Kinetics

G-quadruplexes (G4s) are prevalent in oncogenes and are potential antitumor drug targets. However, binding selectivity of compounds to G4s still faces challenges. Herein, we report a platinum(II) complex (Pt1), whose affinity to G4-DNA is activated by adaptive binding and selectivity controlled by binding kinetics. The resolved structure of Pt1/VEGF-G4 (a promoter G4) shows that Pt1 matches 3'-G-tetrad of VEGF-G4 through Cl^- -dissociation and loop rearrangement of VEGF-G4. Binding rate constants are determined by coordination bond breakage/formation, correlating fully with affinities. The selective rate-determining binding step, Cl^- -dissociation upon G4-binding, is 2-3 orders of magnitude higher than dsDNA. Pt1 potently targets G4 in living cells, effectively represses VEGF expression, and inhibits vascular growth in zebrafish. We show adaptive G4-binding activation and controlled by kinetics, providing a complementary design principle for compounds targeting G4 or similar biomolecules.

Progress of Breast Cancer basic research in China

Breast cancer is the most commonly diagnosed and the most lethal cancer in females both in China and worldwide. Currently, the origin of cancer stem cells, the heterogeneity of cancer cells, the mechanism of cancer metastasis and drug resistance are the most important issues that need to be addressed. Chinese investigators have recently made new discoveries in basic breast cancer researches, especially regarding cancer stem cells, cancer metabolism, and microenvironments. These efforts have led to a deeper understanding of drug resistance and metastasis and have also indicated new biomarkers and therapeutic targets. These findings emphasized the importance of the cancer stem cells for targeted therapy. In this review, we summarized the latest important findings in this field in China.

Ultrabroad-spectrum, multidrug resistant bacteria-killing, and biocompatible quaternized chitin derivative for infected wound healing

Wound infections have consistently been recognized as serious threats to human. The design of antimicrobial and biocompatible wound dressings for infected wounds is an area of constant research. Herein, we homogeneously synthesized an ultrabroad-spectrum antimicrobial and biocompatible quaternized chitin derivative (QC-4) in a high-efficiency and sustainable route using aqueous KOH/urea solution. Particularly, QC-4 displayed powerful multidrug resistant bacteria-killing activities even at a very low antimicrobial concentration range from 500 ng/mL to 5 μg/mL, including clinically prevalent multidrug-resistant Escherichia coli (MDR-E. coli), methicillin resistant Staphylococcus aureus (MRSA), multidrug-resistant Pseudomonas aeruginosa (MRPA), and multidrug-resistant Acinetobacter baumannii (MDR-A. baumannii). With the aim to facilitate clinical translation, we validated the biocompatibility and safety of QC-4 both in vitro and in vivo, and further assessed the effects of QC-4 on infected wound healing in a porcine infectious full-thickness skin wound model. QC-4 demonstrated significant reduction of microbial aggregates and enhanced wound-healing effects by promoted re-epithelialization and collagen deposition, which were quite comparable to that of commercial Alginate-Ag dressing and absolutely superior to commercial Chitoclot Bandage dressing. Additionally, we provided clear evidences that QC-4 had a unique mechanism of action by attracting electrostatically to the negatively charged microbial surface, thus damaging the microbial cell wall and membrane. Findings of this work provided robust preclinical rationale for the future translational applications of QC-4 as a novel ultrabroad-spectrum and multidrug resistant bacteria-killing antimicrobial wound dressing for clinical wound management.