Plant-derived virulence arresting drugs as novel antimicrobial agents: Discovery, perspective, and challenges in clinical use.

Antimicrobial resistance (AMR) emerges as a severe crisis to public health and requires global action. The occurrence of bacterial pathogens with multi-drug resistance appeals to exploring alternative therapeutic strategies. Antivirulence treatment has been a positive substitute in seeking to circumvent AMR, which aims to target virulence factors directly to combat bacterial infections. Accumulated evidence suggests that plant-derived natural products, which have been utilized to treat infectious diseases for centuries, can be abundant sources for screening potential virulence-arresting drugs (VADs) to develop advanced therapeutics for infectious diseases. This review sums up some virulence factors and their actions in various species of bacteria, as well as recent advances pertaining to plant-derived natural products as VAD candidates. Furthermore, we also discuss natural VAD-related clinical trials and patents, the perspective of VAD-based advanced therapeutics for infectious diseases and critical challenges hampering clinical use of VADs, and genomics-guided identification for VAD therapeutic. These newly discovered natural VADs will be encouraging and optimistic candidates that may sustainably combat AMR.

Predictive Value of Carotid Plaque Contrast-Enhanced Ultrasound Score and Homocysteine in Senile Metabolic Syndrome Complicated by Cerebral Infarction.

OBJECTIVE: To investigate the predictive value of the carotid plaque contrast-enhanced ultrasound (CEUS) score and blood homocysteine (HCY) in senile metabolic syndrome (MetS) complicated by cerebral infarction. STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Ultrasound Imaging, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, China, from July 2020 to December 2021. METHODOLOGY: A total of 118 senile MetS patients complicated by cerebral infarction were selected as Group A, and 103 senile MetS patients without cerebral infarction were selected as Group B. Both groups were compared in terms of cardiovascular risk factors and ultrasonic examination of carotid plaques. The independent risk factors for cerebral infarction among senile MetS patients were analysed using logistic regression. An ROC curve was used to assess the predictive value of statistically significant risk factors in senile MetS complicated by cerebral infarction. RESULTS: Significant differences were observed in smoking, abdominal circumference, blood pressure, HCY, fasting blood glucose, high-density and low-density lipoprotein cholesterol, triacylglycerol, carotid plaque thickness, CEUS score, lumen stenosis, and ulcer plaque between the two groups. Logistic regression analysis showed that the plaque CEUS score and HCY were independent risk factors for senile MetS complicated by cerebral infarction. The areas under the ROC curve for the CEUS score and HCY were 0.795 and 0.812, respectively, and was 0.858 for the combined diagnosis of both. When the CEUS score was ≥2 and HCY was ≥16.45 mmol/l, the sensitivity and specificity of predicted senile MetS complicated by cerebral infarction were 83.1% and 74.8%, respectively. CONCLUSION: The carotid plaque CEUS score and blood HCY exhibit a substantial predictive capacity for cerebral infarction in elderly MetS patients. The combined diagnostic efficacy of the two is superior. KEY WORDS: Contrast-enhanced ultrasound, Homocysteine, Elderly, Metabolic syndrome, Cerebral infarction, Carotid plaque.

Chemical profiling and investigation of molecular mechanisms underlying anti-hepatocellular carcinoma activity of extracts from Polygonum perfoliatum L.

Polygonum perfoliatum L. is an herbal medicine that has been extensively used in traditional Chinese medicine to treat various health conditions ranging from ancient internal to surgical and gynecological diseases. Numerous studies suggest that P. perfoliatum extract elicits significant anti-tumor, anti-inflammatory, anti-bacterial, and anti-viral effects. Nevertheless, the underlying mechanisms of its anti-liver cancer effects remain poorly understood. Our study suggests that P. perfoliatum stem extract (PPLA) has a favorable safety profile and exhibits a significant anti-liver cancer effect both in vitro and in vivo. We identified that PPLA activates the cGMP-PKG signaling pathway, and key regulatory genes including ADRA1B, PLCB2, PRKG2, CALML4, and GLO1 involved in this activation. Moreover, PPLA modulates the expression of genes responsible for the cell cycle. Additionally, we identified four constituents of PPLA, namely taxifolin, myricetin, eriodictyol, and pinocembrin, that plausibly act via the cGMP-PKG signaling pathway. Both in vitro and in vivo experiments confirmed that PPLA, along with its constituting compounds taxifolin, myricetin, and eriodictyol, exhibit potent anti-cancer activities and hold the promise of being developed into therapeutic agents.

Chinese herbal medicines for treating ulcerative colitis via regulating gut microbiota-intestinal immunity axis.

Ulcerative colitis (UC) is one of types of inflammatory bowel disease with high recurrence. Recent studies have highlighted that microbial dysbiosis as well as abnormal gut immunity are crucial factors that initiate a series of inflammatory responses in the UC. Modulating the gut microbiota-intestinal immunity loop has been suggested as one of key strategies for relieving UC. Many Chinese herbal medicines including some of single herb, herbal formulas and the derived constituents have been reported with protective effect against UC through modulating gut microbiome and intestinal immunity. Some clinical trials have shown promising results. This review thus focused on the current knowledge on using Chinese herbal medicines for treating UC from the mechanism aspects of regulating intestinal homeostasis involving microbiota and gut immunity. The existing clinical trials are also summarized.

Enhancing Crystallization in Hybrid Perovskite Solar Cells Using Thermally Conductive 2D Boron Nitride Nanosheet Additive.

Controlling crystallization and grain growth is crucial for realizing highly efficient hybrid perovskite solar cells (PSCs). In this work, enhanced PSC photovoltaic performance and stability by accelerating perovskite crystallization and grain growth via 2D hexagonal boron nitride (hBN) nanosheet additives incorporated into the active perovskite layer are demonstrated. In situ X-ray scattering and infrared thermal imaging during the perovskite annealing process revealed the highly thermally conductive hBN nanosheets promoted the phase conversion and grain growth in the perovskite layer by facilitating a more rapid and spatially uniform temperature rise within the perovskite film. Complementary structural, physicochemical, and electrical characterizations further showed that the hBN nanosheets formed a physical barrier at the perovskite grain boundaries and the interfaces with charge transport layers, passivating defects, and retarding ion migration. As a result, the power conversion efficiency of the PSC is improved from 17.4% to 19.8%, along with enhanced device stability, retaining ≈90% of the initial efficiency even after 500 h ambient air storage. The results not only highlight 2D hBN as an effective additive for PSCs but also suggest enhanced thermal transport as one of the pathways for improved PSC performance by 2D material additives in general.

Therapeutic prospects of ceRNAs in COVID-19.

Since the end of 2019, COVID-19 caused by SARS-CoV-2 has spread worldwide, and the understanding of the new coronavirus is in a preliminary stage. Currently, immunotherapy, cell therapy, antiviral therapy, and Chinese herbal medicine have been applied in the clinical treatment of the new coronavirus; however, more efficient and safe drugs to control the progress of the new coronavirus are needed. Long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) may provide new therapeutic targets for novel coronavirus treatments. The first aim of this paper is to review research progress on COVID-19 in the respiratory, immune, digestive, circulatory, urinary, reproductive, and nervous systems. The second aim is to review the body systems and potential therapeutic targets of lncRNAs, miRNAs, and circRNAs in patients with COVID-19. The current research on competing endogenous RNA (ceRNA) (lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA) in SARS-CoV-2 is summarized. Finally, we predict the possible therapeutic targets of four lncRNAs, MALAT1, NEAT1, TUG1, and GAS5, in COVID-19. Importantly, the role of PTEN gene in the ceRNA network predicted by lncRNA MALAT1 and lncRNA TUG1 may help in the discovery and clinical treatment of effective drugs for COVID-19.

Pueraria lobata starch regulates gut microbiota and alleviates high-fat high-cholesterol diet induced non-alcoholic fatty liver disease in mice.

The dried roots of Pueraria lobata (Willd.) Ohwi as an edible medicinal herb are enriched with starch. However, the structure, physiology, and biological bioactivity of P. lobata starch (PLS) has not yet been fully investigated. This study showed that PLS consisted of mixed population of granules with polyhedral or spherical surface. The apparent content of resistant starch was 23.14%, and the molecular weight was 1.93 × 107 Da. PLS showed a branching degree and an average polymerization rate of 2.06% and 20.74%, respectively, with fairly high proportion of B1 short chains. The solubility and swelling power of PLS were 38.51% and 28.10 g/g, respectively, showing high hot stability of the viscosity. In vitro fermentation of PLS resulted in specifically altered composition of gut microbiota and increased production of SCFAs, showing a potential prebiotic effect. Moreover, PLS remarkably alleviated inflammation, hepatic steatosis and dyslipidemia in mice with high-fat high-cholesterol diet induced non-alcoholic fatty liver disease (NAFLD). The protective effect of PLS was associated with amelioration of NAFLD-associated gut dysbiosis through specifically increasing the abundance of Lactobacillus, Bifidobacterium and Turicibacter, and decreasing Desulfovibrio. The results would support the use of PLS as a functional prebiotic for protecting against NAFLD.

The Role of Vitamin D in Gastrointestinal Diseases: Inflammation, Gastric Cancer, and Colorectal Cancer.

Vitamin D as a prohormone is converted into the active form in vivo and binds to vitamin D receptors, exercising a wide range of biological functions. Recent studies strongly support that vitamin D supplementation is associated with reduced cancer risk and a good prognosis. Gastrointestinal cancer is the leading cause of cancer-related deaths worldwide. The key role of vitamin D in the development of gastrointestinal cancer has been observed. Moreover, Vitamin D can also affect innate immunity and perform anti-inflammation and anti-infection actions. Given the intimate relationship between cancer and inflammation, we herein summarize epidemiological and preclinical studies of vitamin D and the underlying mechanism of its action in inflammation, gastric and colorectal cancer by our group and other researchers. A beneficial effect of vitamin D in cancer and inflammatory disease has been supported by different studies. More controlled and larger clinical trials are needed before a reliable conclusion and realization of vitamin D supplementation in the adjunct treatment of gastrointestinal inflammation and cancer.

Quinic acid: a potential antibiofilm agent against clinical resistant Pseudomonas aeruginosa.

BACKGROUND: The biofilm state of pathogens facilitates antimicrobial resistance which makes difficult-to-treat infections. In this regard, it has been found that the compounds screened from plant extracts represent one category of the most promising antibiofilm agents. However, the antibiofilm activities and the active ingredients of plant extracts remain largely unexplored. In this background, the study is (1) to screen out the plant extracts with antibiofilm ability against Pseudomonas aeruginosa, and (2) to identify the active ingredients in the plant extracts and elucidate the underlying mechanism of the antibiofilm activities. METHODS: Micro-broth dilution method, in vitro biofilm model, LC-MS/MS analysis and P. aeruginosa-mouse infection model were adopted to assess the antibiofilm activity. GC-MS analysis was performed to detect the active ingredients in plasma. RNA-Seq, GO analysis, KEGG analysis and RT-qPCR were adopted to elucidate the underlying mechanism of antibiofilm activities against P. aeruginosa. RESULTS: Lonicerae Japonicae Flos (LJF) among 13 plants could exert significant inhibitory effects on bacterial biofilm formation, mobility and toxin release in vitro, and it could exert antibiofilm effect in vivo too. Moreover, quinic acid, as one metabolite of chlorogenic acid, was found as an active ingredient in LJF against the biofilm of P. aeruginosa. The active ingredient significantly inhibited EPS secretion in biofilm formation and maturity and could achieve synergistic antibiofilm effect with levofloxacin. It reduced the biofilm formation by regulating core targets in quorum sensing system. In GO process, it was found that the core targets were significantly enriched in multiple biological processes involving locomotion, chemotaxis and motility mediated by flagellum/cilium, which was related to KEGG pathways such as bacterial chemotaxis, oxidative phosphorylation, ribosome, biofilm formation, cyanoamino acid metabolism and quorum sensing. Finally, the binding of quinic acid with core targets rhlA, rhlR and rhlB were validated by molecular docking and RT-qPCR. CONCLUSIONS: In summary, the study verified the in vitro and in vivo antibiofilm effects of LJF against P. aeruginosa and elucidated the active ingredients in LJF and its conceivable pharmacological mechanism, indicating that quinic acid could have the potential of an antibiofilm agent against P. aeruginosa and related infections.

Excessive Intake of Longan Arillus Alters gut Homeostasis and Aggravates Colitis in Mice.

Background: Longan is the fruit of Dimocarpus longan Lour. and the longan arillus has long been used in traditional Chinese medicine possessing various health benefits. However, the excessive intake of longan is found in daily life to cause "shanghuo" syndrome. "Shanghuo" has been linked to increased disease susceptibility. The present study thus aimed to investigate the toxicological outcomes after excessive longan treatment. Methods: Longan extract at a normal dosage of 4 g/kg and two excess dosages of 8 and 16 g/kg was orally administered to normal C57BL/6J mice for two weeks or to C57BL/6J mice with DSS-induced colitis. Mouse gut microbiome were analyzed by 16S rRNA sequencing. Short chain fatty acid (SCFA) contents in colonic contents were measured by GC-MS. Colon tissue was used for histopathological observation after H and E staining, detection of protein expression by western blot, analysis of gene expression by qPCR, and detection of apoptotic cells by TUNEL assay. ELISA was used for biochemical analysis in serum. Results: In normal mice, repeated longan intake at excess doses, but not the normal dose, increased infiltration of inflammatory cells, elevated serum levels of TNF-α and IL-6 and reduced production of SCFAs. In DSS-induced colitic mice, longan intake at 4 g/kg did not promote colitis in mice, while excessive longan (8 or 16 g/kg) aggravated colitis in mice, showing increased inflammation, more serious histological abnormalities, increased gut permeability, and increased epithelia injury when compared to DSS alone. Excessive longan induced a significant reduction of microbial diversity in colitic mice, accompanied with aggravated alterations of DSS-associated bacteria including the increase of Proteobacteria phylum and genera of Bacteroides, Akkermansia, Turicibacter and Escherchia-Shigella, and the decrease of norank_f__Muribaculaceae. The changed microbial compositions were accompanied with decreased SCFAs when longan was supplemented with DSS. The aggravated colon injury by excessive intake of longan in colitic mice was tightly correlated with the altered microbial communities and decreased SCFAs production. Conclusion: Excessive longan intake disturbs gut homeostasis and aggravates colitis via promoting inflammation and altering gut microbe compositions and associated metabolism in mice. Our findings warrant rational longan arillus consumption as a dietary supplement or herbal medicine.

The dietary supplement Rhodiola crenulata extract alleviates dextran sulfate sodium-induced colitis in mice through anti-inflammation, mediating gut barrier integrity and reshaping the gut microbiome.

Rhodiola species are edible medicinal plants, which have been traditionally used in both Asia and Europe as an adaptogen, a tonic, an anti-depressant and anti-inflammatory supplement. However, whether it presents a therapeutic effect on colitis or not remains unknown. The aim of this study is to investigate the protective effect of a Rhodiola crenulata extract (RCE) on mice with DSS-induced colitis. RCE significantly alleviated the pathological abnormalities in colitic mice, including the correspondingly increased colon length, ameliorated colonic injury and reduced pro-inflammatory factors. The protective effect was similar to that of the positive control, 5-aminosalicylic acid. The DSS-induced epithelial apoptosis and maintained intestinal barrier function were attenuated by RCE through the upregulation of the level of tight junction proteins such as ZO-1 and occludin. Notably, RCE prevented gut dysbiosis in colitic mice by restoring the microbial richness and diversity, and decreasing the abundance of Proteobacteria phylum and opportunistic pathogenic Parasutterella and Staphylococcus, as well as increasing the abundance of beneficial microbes in Lactobacillus and Bifidobacterium, which were closely correlated with its protective effect against colitis. Meanwhile, chemical characterization of RCE was performed by UPLC-HR-MS to explain its material basis. A total of 63 compounds were identified, while the content of two bioactive ingredients (salidroside, 1.81%; rosavin, 0.034%) was determined.

An integrated microbiome and metabolomic analysis identifies immunoenhancing features of Ganoderma lucidum spores oil in mice.

Ganoderma lucidum (Leyss. ex Fr.) Karst. is a valuable dietary supplement used worldwide for promoting health as well as a medicinal fungus for handling fatigue, immunological disorders, and cancer. Previous studies have revealed the immunoenhancing effect of G. lucidum and the polysaccharide extract, with potential involvement of gut microbiome. The oil of G. lucidum spores (GLSO)is one of the well-known G. lucidum-related products. However, there is little evidence supporting the immune promotion activity and the underlying mechanisms. The present study aims to investigate the immunoenhancing effect of GLSO in mice. GLSO enhanced macrophage phagocytosis and NK cell cytotoxicity of mice. Further microbiome and metabolomics studies showed that GLSO induced structural rearrangement of gut microbiota, mediating alterations in a wide range of metabolites. By clustering, multivariate and correlation analysis, the immunoenhancing effect of GLSO was found to be highly correlated with elevated abundance of several bacterial genera (Lactobacillus, Turicibacter and Romboutsia) and species (Lactobacillus_intestinalis and Lactobacillus_reuteri), and decreased level of Staphylococcus and Helicobacter, which resulted in the regulation of a range of key metabolites such as dopamine, prolyl-glutamine, pentahomomethionine, leucyl-glutamine, l-threonine, stearoylcarnitine, dolichyl ß-d-glucosyl phosphate, etc. These results provide new insights into the understanding of the modulatory effect of GLSO on immune system.

Characterization of chemical composition and prebiotic effect of a dietary medicinal plant Penthorum chinense Pursh.

Penthorum chinense Pursh is a dietary medicinal plant widely distributed in Asia-Pacific countries. The present study aims to profile the chemical constituents of P. chinense and investigate its prebiotic role in modulating gut microbiota. Fifty polyphenolic compounds were rapidly identified using UPLC-HR-MS. Total flavonoid and phenolic contents of P. chinense were 46.6% and 61.3% (w/w), respectively. Thirteen individual polyphenols were quantified, which accounted for 33.1% (w/w). P. chinense induced structural arrangement of microbial community in mice, showing increased microbiota diversity, elevated Bacteroidetes/Firmicutes ratio and enriched gut health-promoting bacteria. After a one-week drug-free wash, most of these changes were recovered, but the abundance of some beneficial bacteria was further increased. The altered composition of gut microbiota enriched several metabolic pathways. Moreover, P. chinense increased antioxidant capacity in vivo. The results suggest that polyphenol-enriched P. chinense modulates gut microbiota and enhances antioxidant capacity in mice toward a beneficial environment for host health.

A review of Penthorum chinense Pursh for hepatoprotection: Traditional use, phytochemistry, pharmacology, toxicology and clinical trials.

ETHNOPHARMACOLOGICAL RELEVANCE: In China, Penthorum chinense Pursh (P. chinense) has been used for hundreds of years traditionally for alleviating symptoms by excessive intake of alcohol as well as in the treatment of traumatic injury, edema and liver diseases. Recently, P. chinense and its extract have been developed into tea, drinks or medicines for treatment of liver diseases, including hepatic virus infections, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD) and liver fibrosis. AIM OF THE STUDY: The main purpose of this review is to provide a critical appraisal of the existing knowledge on the phytochemical data, quality control aspect, pharmacological, as well as toxicological and clinical studies performed on P. chinense, including the identification of scientific gaps. MATERIALS AND METHODS: A detailed literature search was conducted using various online search engines, such as Pubmed, Scopus, Google Scholar, Mendeley, Web of Science as well as China National Knowledge Infrastructure (CNKI) database. RESULTS: In the pharmacological studies, there clearly are links between local/traditional uses and the biomedical investigations. Most pharmacological studies indicated potential liver protective effects in experimental models of chemicals-induced liver injury, acute and chronic alcoholic liver injury, NAFLD, liver fibrosis and viral infection, potentially through antioxidant effects, balancing key liver enzyme levels, inhibition of hepatic virus DNA replication, inhibition of hepatic stellate cells activation and inflammation either in vitro or in vivo. In some models, the effects of P. chinense is comparable with the one of silymarin. Clinical studies have suggested that P. chinense is safe and effective in treating several liver diseases, although most of them are not double-blinded and placebo-controlled studies. Toxicology studies show that P. chinense has no obvious toxicity or side effects in animals or human. Flavonoids, lignans, coumarins, polyphenols and organic acids have been identified. However, only a few studies have investigated the active compounds (mainly flavonoids and lignans) and molecular mechanisms of P. chinense. CONCLUSION: P. chinense seems to be safe and shows relevant liver protecting effects. Therefore, it might be a promising candidate for developing as new hepatoprotective agents. However, a lack of understanding of the active compounds and mechanisms of action needs further attention.

Targets and mechanisms of sulforaphane derivatives obtained from cruciferous plants with special focus on breast cancer - contradictory effects and future perspectives.

Breast cancer is the most common type of cancer among women. Therefore, discovery of new and effective drugs with fewer side effects is necessary to treat it. Sulforaphane (SFN) is an organosulfur compound obtained from cruciferous plants, such as broccoli and mustard, and it has the potential to treat breast cancer. Hence, it is vital to find out how SFN targets certain genes and cellular pathways in treating breast cancer. In this review, molecular targets and cellular pathways of SFN are described. Studies have shown SFN inhibits cell proliferation, causes apoptosis, stops cell cycle and has anti-oxidant activities. Increasing reactive oxygen species (ROS) produces oxidative stress, activates inflammatory transcription factors, and these result in inflammation leading to cancer. Increasing anti-oxidant potential of cells and discovering new targets to reduce ROS creation reduces oxidative stress and it eventually reduces cancer risks. In short, SFN effectively affects histone deacetylases involved in chromatin remodeling, gene expression, and Nrf2 anti-oxidant signaling. This review points to the potential of SFN to treat breast cancer as well as the importance of other new cruciferous compounds, derived from and isolated from mustard, to target Keap1 and Akt, two key regulators of cellular homeostasis.

Melanin-loaded biocompatible photosensitive nanoparticles for controlled drug release in combined photothermal-chemotherapy guided by photoacoustic/ultrasound dual-modality imaging.

Combined photothermal-chemotherapy guided by multimodal imaging is a promising strategy for cancer diagnosis and treatment. Multifunctional nanoparticles, such as those comprising organic and inorganic compounds, have been extensively investigated for combined photothermal-chemotherapy; however, their application is still limited by their potential long-term toxicity and lack of contrast properties. To solve these problems, in this study, a new type of multifunctional nanoparticle for combined photothermal-chemotherapy guided by dual-modality imaging was prepared with endogenous melanin by multistep emulsification to enhance tumor ablation. The nanoparticles were coated with poly(lactide-co-glycolic acid) (PLGA) and loaded with paclitaxel (PTX), encapsulated melanin and perfluoropentane (PFP). The materials in the nanoparticles were endogenous, ensuring high stability, biocompatibility, and biosafety. Nanoparticles irradiated with a laser, which induced their phase transformation into microbubbles, exhibited high photothermal conversion efficiency, thereby achieving photoacoustic (PA)/ultrasound (US) dual-modality imaging to determine tumor location, boundary, and size and to monitor drug distribution. Furthermore, optical droplet vaporization (ODV) of the nanoparticles could trigger the release of PTX; thus, these nanoparticles are a useful drug carrier. In vivo and in vitro experiments revealed that a strong synergistic antitumor effect was achieved by combining the photothermal properties of the nanoparticles with a chemotherapy drug. Importantly, the cavitation, thermoelastic expansion, and sonoporation caused by the phase transformation of the nanoparticles could directly damage the tumors. These processes also promoted the release, penetration and absorption of the drug, further enhancing the effect of combined photothermal-chemotherapy on tumor suppression. Therefore, the multifunctional nanoparticles prepared in this study provide a new strategy of using endogenous materials for controlled near-infrared (NIR)-responsive drug release and combined photothermal-chemotherapy guided by multimodal imaging.

Repurposing vitamin D for treatment of human malignancies via targeting tumor microenvironment.

Tumor cells along with a small proportion of cancer stem cells exist in a stromal microenvironment consisting of vasculature, cancer-associated fibroblasts, immune cells and extracellular components. Recent epidemiological and clinical studies strongly support that vitamin D supplementation is associated with reduced cancer risk and favorable prognosis. Experimental results suggest that vitamin D not only suppresses cancer cells, but also regulates tumor microenvironment to facilitate tumor repression. In this review, we have outlined the current knowledge on epidemiological studies and clinical trials of vitamin D. Notably, we summarized and discussed the anticancer action of vitamin D in cancer cells, cancer stem cells and stroma cells in tumor microenvironment, providing a better understanding of the role of vitamin D in cancer. We presently re-propose vitamin D to be a novel and economical anticancer agent.

Combination of shikonin with paclitaxel overcomes multidrug resistance in human ovarian carcinoma cells in a P-gp-independent manner through enhanced ROS generation.

BACKGROUND: Shikonin (SKN), a naphthoquinone compound, is isolated from Chinese herbal medicine Lithospermum root and has been studied as an anticancer drug candidate in human tumor models. This study is designed to investigate whether SKN can sensitize the therapeutic effect of paclitaxel (PTX) in drug-resistant human ovarian carcinoma cells. METHODS: Human ovarian carcinoma A2780 cell along with the paired PTX-resistant A2780/PTX cells were used. The effects of SKN, PTX or their combination on cell viability were conducted using Sulforhodamine B assay. P-glycoprotein (P-gp) expression was analyzed by flow cytometry after staining with P-gp-FITC anti-body. P-gp activity was determined by a fluorometric MDR assay kit or a rhodamine 123-based efflux assay, respectively. Apoptosis was evaluated by flow cytometry after Annexin V-FITC/PI co-staining. The effect of SKN, PTX or their combination on reactive oxygen species (ROS) generation and expression of pyruvate kinase M2 (PKM2) were investigated using flow cytometry or western blotting, respectively. PKM2 activity was detected by a Pyruvate Kinase Assay Kit. RESULTS: SKN/PTX co-treatment led to synergistically enhanced cytotoxicity and apoptosis in PTX-resistant ovarian cancer cells, indicating the circumvention of multidrug resistance (MDR) of PTX by SKN. Further study indicated that the MDR reversal effect of SKN was independent of inhibiting activity of the efflux transporter P-gp. Notably, SKN/PTX significantly increased the generation of intracellular ROS in A2780/PTX cells, and scavenging intracellular ROS blocked the sensitizing effects of SKN in PTX-induced cytotoxicity and apoptosis in A2780/PTX cells, but not in A2780 cells. Furthermore, SKN/PTX-induced downregulation of PKM2 (a key enzyme in glycolysis) and the suppression of its activity were inhibited by a ROS scavenger N-acetyl cysteine (NAC), suggesting that the synergy of the SKN/PTX combination may be not rely on PKM2 suppression. CONCLUSIONS: These results reveal a P-gp-independent mechanism through ROS generation for the SKN/PTX combination to overcome MDR in ovarian cancer.