Design and synthesis of cantharidin derivative DCZ5418 as a TRIP13 inhibitor with anti-multiple myeloma activity in vitro and in vivo.

Natural product cantharidin can inhibit multiple myeloma cell growth in vitro, while serious adverse effects limited its clinical application. Therefore, the structural modification of cantharidin is needed. Herein, inspired by the structural similarity of the aliphatic endocyclic moiety in cantharidin and TRIP13 inhibitor DCZ0415, we designed and synthesized DCZ5418 and its nineteen derivatives. The molecular docking study indicated that DCZ5418 had a similar binding mode to TRIP13 protein as DCZ0415 while with a stronger docking score. Moreover, the bioassay studies of the MM-cells viability inhibition, TRIP13 protein binding affinity and enzyme inhibiting activity showed that DCZ5418 had good anti-MM activity in vitro and definite interaction with TRIP13 protein. The acute toxicity test of DCZ5418 showed less toxicity in vivo than cantharidin. Furthermore, DCZ5418 showed good anti-MM effects in vivo with a lower dose administration than DCZ0415 (15 mg/kg vs 25 mg/kg) on the tumor xenograft models. Thus, we obtained a new TRIP13 inhibitor DCZ5418 with improved safety and good activity in vivo, which provides a new example of lead optimization by using the structural fragments of natural products.

Five New Cantharidin Derivatives from the Insect Mylabris cichorii L. and Their Potential against Kidney Fibrosis In Vitro.

Five new monoterpenoids including three 1-hydroxymethyl-2-methyl cantharimide-type derivatives (1, 2, and 5) and two 1,2-dimethyl cantharimide-type derivatives (3 and 4), together with three known compounds (6-8) were isolated from the insect Mylabris cichorii Linnaeus. The structures of these new compounds, including their absolute configurations, were characterized by detailed analysis of NMR, chemical derivatization, and quantum chemical ECD calculations. All of the compounds were tested for their biological activity against kidney fibrosis. The results revealed that compounds 2, 4, and 7 could inhibit kidney fibrosis in vitro at 40 µM by inhibiting the expression of fibronectin and collagen I in TGF-ß1-induced NRK-52e cells.

Use of different ligand modification liposomes to evaluate the anti-liver tumor activity of cantharidin.

In this study, cantharidin(CTD), a bioactive terpenoid in traditional Chinese medicine cantharidin, was selected as a model component to construct novel nano liposome delivery systems for hepatocellular carcinoma therapy. Previous studies have shown that although cantharidin has definite curative effects on primary liver cancer, it is associated with numerous toxic and side effects. Therefore, based on the glycyrrhetinic acid (GA) binding site and the asialoglycoprotein receptor (ASGPR) on the hepatocyte membrane, the surface of CTD liposomes was modified with stearyl alcohol galactoside (SA-Gal) or/and the newly synthesized 3-succinic-30-stearyl deoxyglycyrrhetinic acid (11-DGA-Suc) ligands, and the physicochemical properties, pharmacokinetics, in vivo and in vitro anti-liver tumor activity and its mechanism of modified liposomes were investigated. Compared to CTD-lip, SA-Gal-CTD-lip, and 11-DGA-Suc + SA-Gal-CTD-lip, 11-DGA-Suc-CTD-lip showed stronger cytotoxicity and increased inhibition of HepG2 cell migration had the highest apoptosis rate. The cell cycle results indicated that HepG2 cells was arrested mainly at G0/G1phase and G2/M phase. The results of in vivo pharmacokinetic experiments revealed that the distribution of modified liposomes in the liver was significantly increased compared with that of unmodified liposome. In vivo tumor inhibition experiment showed that 11-DGA-Suc-CTD-lip had excellent tumor inhibition, and the tumor inhibition rates was 80.96%. The 11-DGA-Suc-CTD-lip group also displayed the strongest proliferation inhibition with the lowest proliferation index of 7% in PCNA assay and the highest apoptotic index of 49% in TUNEL assay. Taken together, our findings provide a promising solution for improving the targeting of nano liposomes and further demonstrates the encouraging potential of poor solubility and high toxicity drugs applicable to tumor therapy.

Network Pharmacology Integrated Molecular Docking to Explore the Mechanism of Blister Beetle Therapy for Lung Adenocarcinoma.

Lung adenocarcinoma (LUAD) is one of the major causes of cancer death in the world. Studies show that the effective anticancer component in blister beetles is cantharidin, which can improve chemotherapy efficacy, median survival, and prognosis of LUAD. However, the antitumor mechanism of blister beetles has not been fully clarified. This study aimed to identify the key targets of the treatment of LUAD by blister beetles based on the principle of network pharmacology. An integrated approach including network pharmacology and a molecular docking technique was conducted, which mainly comprises target prediction, weighted gene correlation network analysis (WGCNA) analysis, network construction, gene ontology, and pathway enrichment analysis. 35 key targets were obtained and significantly associated with response to external stimuli, collagen binding, cyclin binding, organic acid binding, pyruvate metabolism, glycolysis, and amino acid biosynthesis pathways. Both LASSO regression and the RF model had a high predictive ability, and 9 candidate genes were screened, among which BIRC5 and PLK1 were the key targets for the treatment of LUAD by using blister beetles and showed significant survival significance. Cantharidin exerts its antitumor effects through 8 targets in 32 pathways, while BIRC5 and PLK1 have obvious survival significance.

Pharmacokinetics and tissue distribution of cantharidin after oral administration of aqueous extracts from Mylabris in rats.

A sensitive gas chromatography-mass spectroscopy method was established for the determination of cantharidin (CTD) in rat plasma and liver homogenates. During the experiment, rats were randomly divided into two groups (low, high) and were administered aqueous extract of Mylabris compound for 7 days. Then, plasma and tissue samples were taken at different time points to study the pharmacokinetics and tissue distribution of CTD in rats. The selected reaction monitoring transitions for CTD and clofibrate (internal standard) were m/z 128 → 85 and m/z 169 → 141, respectively. The calibration curve ranged from 10.26 to 3,078 ng/ml for plasma and from 10.26 to 246.24 ng/ml for liver homogenates. The lower limits of quantification were 10.26 ng/ml for both plasma and liver. The intra- and inter-day precision and accuracy were <20% for both plasma and liver homogenates. Extraction recovery ranged from 89.21 to 103.61% for CTD in rat plasma and liver and from 83.79 to 102.74% for IS in rat plasma and liver. Matrix effects ranged from 93.06 to 110.44% for CTD and from 91.65 to 110.80% for IS.

Combination of Sodium Cantharidinate with Cisplatin Synergistically Hampers Growth of Cervical Cancer.

BACKGROUND: Sodium cantharidinate (SC) has been broadly applied in lung cancer treatment in China, while its specific function in cervical cancer (CC), a great contributor to death of female reproductive system cancers, remains unclear. Our research evaluated the anti-tumor effects of SC in CC and the mechanism involved. METHODS: First, cisplatin (DDP)-resistant Caski-1 and ME180 cell lines were developed and treated with SC. The effects of SC on CC cell growth were then evaluated. Subsequently, the genes targeted by SC were predicted via the bioinformatics website. The correlations between PTPN1 expression and tumor stage, lymph node metastasis and tumor differentiation were examined. We further conducted rescue experiments by overexpressing PTPN1 in CC cells, followed by SC and cisplatin treatments. The activation of the PI3K/AKT pathway in CC cells, and the effect of SC on the growth and drug resistance of Caski-1 cells in vivo were investigated. RESULTS: The sensitivity of Caski-1 and ME180 cells to DDP was increased after SC treatment, which also enhanced the inhibitory effect of DDP on the cell growth. By prediction, we found that SC could target PTPN1. Patients with high expression of PTPN1 had higher clinical stage, lymph node metastasis and lower tumor differentiation. SC inhibited PTPN1 expression. Overexpression of PTPN1 attenuated the effect of SC. Furthermore, PTPN1 activated the PI3K/AKT pathway. Moreover, SC treatment inhibited the growth and drug resistance of Caski-1 cells in vivo. CONCLUSION: SC promotes drug sensitivity of CC cells to DDP by targeting PTPN1, thereby impairing the PI3K/AKT pathway.

Antitumor potential of the protein phosphatase inhibitor, cantharidin, and selected derivatives.

Cantharidin is a potent natural protein phosphatase monoterpene anhydride inhibitor secreted by several species of blister beetle, with its demethylated anhydride analogue, (S)-palasonin, occurring as a constituent of the higher plant Butea frondosa. Cantharidin shows both potent protein phosphatase inhibitory and cancer cell cytotoxic activities, but possible preclinical development of this anhydride has been limited thus far by its toxicity. Thus, several synthetic derivatives of cantharidin have been prepared, of which some compounds exhibit improved antitumor potential and may have use as lead compounds. In the present review, the potential antitumor activity, structure-activity relationships, and development of cantharidin-based anticancer drug conjugates are summarized, with protein phosphatase-related and other types of mechanisms of action discussed. Protein phosphatases play a key role in the tumor microenvironment, and thus described herein is also the potential for developing new tumor microenvironment-targeted cancer chemotherapeutic agents, based on cantharidin and its naturally occurring analogues and synthetic derivatives.

Norcantharidin: research advances in pharmaceutical activities and derivatives in recent years.

Cantharidin (CTD) is the main bioactive component of Cantharides, which is called Banmao in Traditional Chinese Medicine (TCM). Norcantharidin (NCTD) is a structural modifier of CTD. To compare with CTD, NCTD has lighter side effects and stronger bioactivity in anti-cancer through inhibiting cell proliferation, causing apoptosis and autophagy, overwhelming migration and metastasis, affecting immunity as well as lymphangiogenesis. Examples of these effects include suppressing Protein Phosphatase 2A and modulating Wnt/beta catenin signal, with Caspase family proteins, AMPK pathway and c-Met/EGFR pathway involving respectively. Moreover, NCTD has the effects of immune enhancement, anti-platelet aggregation and inhibition of renal interstitial fibrosis with distinct signaling pathways. The immunological effects induced by NCTD are related to the regulation of macrophage polarization and LPS-mediated immune response. The antiplatelet activity that NCTD induced is relevant to the inhibition of platelet signaling and the downregulation of α2 integrin. Furthermore, some of novel derivatives designed and synthesized artificially show stronger biological activities (e.g., anticancer effect, enzyme inhibition effect, antioxidant effect) and lower toxicity than NCTD itself. Plenty of literatures have reported various pharmacological effects of NCTD, particularly the anticancer effect, which has been widely concerned in clinical application and laboratory research. In this review, the pharmaceutical activities and derivatives of NCTD are discussed, which can be reference for further study.

Inhibition of Jurkat T Cell Growth by N-farnesyl-norcantharimide Through Up-regulation of Tumor Suppressor Genes and Down-regulation of Genes for Steroid Biosynthesis, Metabolic Pathways and Fatty Acid Metabolism.

BACKGROUND/AIM: To evaluate the anti-cancer mechanism of N-Farnesyl-norcantharimide (NC15). MATERIALS AND METHODS: The viability of NC15-treated human leukemic Jurkat T (JKT) cells was assessed using the Kit-8 cell counting method. Flow cytometry analysis, human apoptosis antibody array assay, and whole genome sequencing were adopted to investigate the mechanism underlying the anti-cancer activity of NC15 in JKT cells. RESULTS: The growth inhibition rates of NC15 in JKT cells were about 80% and 95% after treatment with 8 µmol/l NC15 for 24 and 48 h, respectively. The percentages of NC15-treated JKT cells in the sub-G1 phase at 24 and 48 h were 22.0% and 34.3%, respectively, in contrast to the 1.5% in the control. Next-generation sequencing showed that many tumor suppressor genes (TSG) were up-regulated, while many genes associated with steroid biosynthesis, metabolic pathways, and fatty acid metabolism were down-regulated. CONCLUSION: NC15 can reduce the cell viability and increase the percentage of JKT cells in the sub-G1 phase by up-regulating TSG and related genes, and down-regulating the genes for steroid biosynthesis, metabolic pathways and fatty acid metabolism, instead of through apoptosis.

Cantharidin-loaded functional mesoporous titanium peroxide nanoparticles for non-small cell lung cancer targeted chemotherapy combined with high effective photodynamic therapy.

BACKGROUND: Although photodynamic therapy (PDT) has emerged as a potential alternative to conventional chemotherapy, the low reactive oxygen species (ROS) yield of the photosensitizer such as TiO2 nanoparticles has limited its application. In addition, it is difficult to achieve effective tumor treatment with a single tumor therapy. METHODS: We used TiOx nanocomposite (YSA-PEG-TiOX ) instead of TiO2 as a photosensitizer to solve the problem of insufficient ROS generation in PDT. Benefiting from the desired mesoporous structure of TiOx, Cantharidin (CTD), one of the active components of mylabris, is loaded into TiOx for targeted combination of chemotherapy and PDT. The cellular uptake in human non-small cell lung carcinoma cell line (A549) and human normal breast cell line (MCF 10A) was evaluated by confocal microscopy. in vitro cytotoxicity was evaluated using Cell Counting Kit-8 assay. The ROS was detected via a chemical probe DCFH-DA and the photodynamic treatment effect of YSA-PEG-TiOx was further evaluated by a living-dead staining. The cell apoptosis was detected by the flow cytometry. RESULTS: Our findings showed that the modification of YSA peptide improved the cytotoxicity of YSA-PEG-TiOX /CTD to EphA2 overexpressing A549 non-small cell lung cancer (NSCLC) than non-YSA modified counterparts. In addition, TiOx generated adequate ROS under X-ray irradiation to further kill cancer cells. Flow analysis results also proved the superiority of this combined treatment. CONCLUSIONS: YSA-PEG-TiOX nanoparticles could significantly increase ROS production under X-ray exposure and provide a new drug delivery nanocarrier for CTD in combination with PDT to achieve effective NSCLC treatment.

Rapid profiling of cantharidin analogs in Mylabris phalerata Pallas by ultra-performance liquid chromatography-quadrupole time-of-flight-tandem mass spectrometry.

We evaluated the protective effect and toxicity of extracts from Mylabris phalerata Pallas by measuring the activated partial thromboplastin time, prothrombin time, venous thrombosis and acute toxicity in rats. Results showed the petroleum ether and water fractions of M. phalerata inhibited thrombosis but hardly prolonged the activated partial thromboplastin time and prothrombin time in rats. The trichloromethane fraction had obvious toxicity with an LD50 of 0.2 g/kg in vivo, and contained many cantharidin analogs (CAs) by ultra-performance liquid chromatography-quadrupole ion trap-tandem mass spectrometry (UPLC-QTRAP-MS/MS). CAs are the major potential bioactivity constituent in M. phalerata. An effective and reliable UPLC-QTRAP-MS/MS method was successfully developed to separate and identify CAs. The fragmentation patterns of five purified compounds were applied to elucidate the structure of their analogs. Thirty-four CAs were characterized or tentatively identified, eight of which are proposed to be novel compounds (13-17, 20, 21, 23), and their fragmentation patterns were investigated for the first time. Most importantly, a rapid and reliable UPLC-MS method was developed to identify the CAs of M. phalerata. This method has contributed to the discovery of most of these unknown analogs or their metabolites in M. phalerata effectively and quickly, and does not rely on limited chemical structural diversity libraries.

Development of 11-DGA-3-O-Gal-Modified Cantharidin Liposomes for Treatment of Hepatocellular Carcinoma.

BACKGROUND: Liver cancer is a common malignant tumor worldwide, and its morbidity and mortality increase each year. The disease has a short course and high mortality, making it a serious threat to human health. PURPOSE: The objective of this study was to create novel liver-targeting nanoliposomes to encapsulate cantharidin (CTD) as a potential treatment for hepatic carcinoma. METHODS: 3-Galactosidase-30-stearyl deoxyglycyrrhetinic acid (11-DGA-3-O-Gal)-modified liposomes (11-DGA-3-O-Gal-CTD-lip) for the liver-targeted delivery of CTD were prepared via the film-dispersion method and characterized. In vitro analyses of the effects on cellular cytotoxicity, cell migration, cell cycle, and cell apoptosis were carried out and an in vivo pharmacokinetics study and tissue distribution analysis were performed. RESULTS: Compared with unmodified liposomes (CTD-lip), 11-DGA-3-O-Gal-CTD-lip showed higher cytotoxicity and increased the inhibition of HepG2 cell migration, but they did not increase the apoptotic rate of cells. The inhibition mechanism of 11-DGA-3-O-Gal-CTD-lip on hepatocellular carcinoma was partly through cell cycle arrest at the S phase. Analysis of pharmacokinetic parameters indicated that 11-DGA-3-O-Gal-CTD-lip were eliminated more rapidly than CTD-lip. Regarding tissue distribution, the targeting efficiency of 11-DGA-3-O-Gal-CTD-lip to the liver was (41.15 ± 3.28)%, relative targeting efficiency was (1.53 ± 0.31)%, relative uptake rate was( 1.69 ± 0.37)%, and peak concentration ratio was (2.68 ± 0.12)%. CONCLUSION: 11-DGA-3-O-Gal-CTD-lip represent a promising nanocarrier for the liver-targeted delivery of antitumor drugs to treat hepatocellular carcinoma.

Light-activatable dual prodrug polymer nanoparticle for precise synergistic chemotherapy guided by drug-mediated computed tomography imaging.

The synergistic efficacy and clinical application of light-responsive polymeric co-delivery systems are severely restricted by uncontrollable/imprecise drug loading, release, and adverse effects caused by the introduction of additional light-responsive molecules or contrast agents when diagnostic imaging is applied to guide therapy. Here, we report the design of a light-activatable dual prodrug polymer nanoparticle (DPP NP) for precise synergistic chemotherapy guided by drug-mediated computed tomography (DMCT) imaging without the introduction of any additional diagnostic imaging agent. DPP NP enables visible light-triggered prodrug polymer backbone cleavage and bioactive Pt(II) release in cancer cell/tumor site; the light-cleaved polymer fragments are further hydrolyzed to produce demethyl cantharidin (DMC). Notably, the drug loading ratio of Pt(IV) and DMC in DPP NP was fixed at an optimal value to achieve maximum synergistic cancer cell killing, which was kept even after cellular uptake, thereby resulting in enhanced synergistic antitumor efficacy both in vitro and in vivo. Because of the high content of the heavy metal Pt in the polymer chain, the spatial/temporal dynamic biodistribution as well as metabolism of DPP NP in vivo can be monitored by Pt DMCT imaging to guide the light irradiation parameters for optimized light-activatable synergistic chemotherapy. Guided by Pt DMCT imaging, DPP NP was able to achieve an improved light-activatable antitumor efficacy, with 75% tumors fully cured and low toxicity. The light-activatable DDP NP system exhibits tremendous potential as precise theranostic nanomedicine. STATEMENT OF SIGNIFICANCE: The synergistic efficacy and clinical application of light-responsive polymeric co-delivery systems are severely restricted by uncontrollable/imprecise drug loading, delivery, and release, as well as adverse effects caused by the introduction of additional light-responsive molecules or contrast agents when diagnostic imaging is applied to guide therapy. Herein, we report the design of a light-activatable dual prodrug polymer nanoparticle (DPP NP) for precise synergistic chemotherapy guided by drug-mediated computed tomography imaging without the introduction of any additional diagnostic imaging agents. Notably, the drug loading ratio of Pt(II) and DMC in DPP NP was fixed at an optimal value to achieve maximum synergistic cancer cell killing, which was kept even after cellular uptake, thereby resulting in enhanced synergistic antitumor efficacy both in vitro and in vivo. The light-activatable DDP NP system exhibits tremendous potential as precise theranostic nanomedicine.

Interactions of cantharidin-like inhibitors with human protein phosphatase-5 in a Mg2+ system: molecular dynamics and quantum calculations.

The serine/threonine protein phosphatase type 5 (PP5) is a promising target for designing new antitumor drugs. This enzyme is a member of the PPP phosphatases gene family, which catalyzes a dephosphorylation reaction: a regulatory process in the signal transduction pathway that controls various biological processes. The aim of this work is to study and compare the inhibition of PP5 by ten cantharidin-like inhibitors in order to bring about contributions relevant to the better comprehension of their inhibitory activity. In this theoretical investigation, we used molecular dynamics techniques to understand the role of key interactions that occur in the protein active site; QM calculations were employed to study the interaction mode of these inhibitors in the enzyme. In addition, atoms in molecules (AIM) calculations were carried out to characterize the chemical bonds among the atoms involved and investigate the orbital interactions with their respective energy values. The obtained results suggest that the Arg275, Asn303, His304, His352, Arg400, His427, Glu428, Val429, Tyr451, and Phe446 residues favorably contribute to the interactions between inhibitors and PP5. However, the Asp271 and Asp244 amino acid residues do not favor such interactions for some inhibitors. Through the QM calculations, we can suggest that the reactional energy of the coordination mechanism of these inhibitors in the PP5 active site is quite important and is responsible for the inhibitory activity. The AIM technique employed in this work was essential to get a better comprehension of the transition states acquired from the mechanism simulation. This work offers insights of how cantharidin-like inhibitors interact with human PP5, potentially allowing the design of more specific and even less cytotoxic drugs for cancer treatments. Graphical Abstract Interactions of cantharidin-like inhibitors with human protein phosphatase-5 in a Mg2+ system.

Bioassay-guided isolation of cantharidin from blister beetles and its anticancer activity through inhibition of epidermal growth factor receptor-mediated STAT3 and Akt pathways.

Cantharidin is an active constituent of blister beetles (cantharides) which have traditionally been used for cancer treatment. Several studies have shown that cantharidin has a cytotoxic effect on various cancer cells. However, few studies have examined the effect of cantharidin on signal transducer and activator of transcription 3 (STAT3) signaling in cancer. In this study, we isolated cantharidin from cantharides by bioassay-guided fractionation and examined its inhibitory effect on STAT3 activation in human breast cancer MDA-MB-231 cells, expressing high level of phosphorylated STAT3. Cantharides were extracted with acetonitrile and separated into hexane, methylene chloride/acetonitrile, and water fractions. The methylene chloride/acetonitrile fraction was further separated into four fractions by preparative high-throughput high-performance liquid chromatography. Cantharidin was then isolated from the third fraction by countercurrent chromatography and structurally determined by comparing nuclear magnetic resonance and high-resolution mass spectrometry data. Cantharidin inhibited STAT3 tyrosine phosphorylation in MDA-MB-231 cells. Cantharidin suppressed epidermal growth factor (EGF)-induced STAT3 and PI3K/Akt signaling pathways through inhibition of EGF receptor phosphorylation. Moreover, cantharidin reduced cell proliferation and induced apoptosis with downregulation of STAT3 target genes, such as Bcl-2, COX-2, and cyclin D1. Taken together, this study provides evidence that cantharidin may be a potential therapeutic agent for triple-negative breast cancer by reducing EGFR-mediated STAT3 and Akt signaling pathways.

Cantharidin-encapsulated thermal-sensitive liposomes coated with gold nanoparticles for enhanced photothermal therapy on A431 cells.

PURPOSE: Plasmonic nanostructure-mediated photothermal therapy (PTT) is a promising alternative therapy for the treatment of skin cancer and other diseases. However, the insufficient efficiency of PTT at irradiation levels tolerable to tissues and the limited biodegradability of nanomaterials are still crucial challenges. In this study, a novel nanosystem for PTT based on liposome-nanoparticle assemblies (LNAs) was established. MATERIALS AND METHODS: Thermal-sensitive liposomes (TSLs) encapsulating cantharidin (CTD) were coated with gold nanoparticles (GNPs) and used in near-infrared (NIR) illumination-triggered PTT and thermally induced disruption on A431 cells. RESULTS: The coated GNPs disintegrated into small particles of 5-6 nm after disruption of TSLs, allowing their clearance by the liver and kidneys. CTD encapsulated in the TSLs was released into cytoplasm after PTT. The released CTD increased the apoptosis of PTT-treated tumor cells by blocking the heat shock response (HSR) and inhibiting the expression of HSP70 and BAG3 inhibiting the expression of HSP70 and BAG3 with the synergistic enhancement of CTD, the new nanosystem CTD-encapsulated TSLs coated with GNPs (CTD-TSL@GNPs) had an efficient PTT effect using clinically acceptable irradiation power (200 mW//cm2) on A431 cells. CONCLUSION: The developed CTD-TSL@GNPs may be a promising PTT agent for clinical skin cancer therapy.

Caffeic acid phenethyl ester down-regulates claudin-2 expression at the transcriptional and post-translational levels and enhances chemosensitivity to doxorubicin in lung adenocarcinoma A549 cells.

Claudin-2 is highly expressed in human lung adenocarcinoma cells and involved in the promotion of proliferation. Here, we searched for a compound, which can decrease claudin-2 expression using lung adenocarcinoma A549 cells. In the screening using compounds included in royal jelly and propolis, the protein level of claudin-2 was dose-dependently decreased by caffeic acid phenethyl ester (CAPE), whereas the mRNA level and promoter activity were only decreased by 50 µM CAPE. These results suggest that CAPE down-regulates claudin-2 expression mediated by two different mechanisms. CAPE (50 µM) decreased the level of p-NF-κB, whereas it increased that of IκB. The CAPE-induced decrease in promoter activity of claudin-2 was blocked by the mutation in an NF-κB-binding site. The inhibition of NF-κB may be involved in the decrease in mRNA level of claudin-2. The CAPE (10 µM)-induced decrease in claudin-2 expression was inhibited by chloroquine, a lysosomal inhibitor. CAPE increased the expression and activity of protein phosphatase (PP) 1 and 2A. The CAPE-induced decrease in claudin-2 expression was blocked by cantharidin, a potent PPs inhibitor. The cell proliferation was suppressed by CAPE, which was partially rescued by ectopic expression of claudin-2. In addition, the toxicity and accumulation of doxorubicin in 3D spheroid cells were enhanced by CAPE, which was inhibited by ectopic expression of claudin-2. Taken together, CAPE down-regulates claudin-2 expression at the transcriptional and post-translational levels, and enhances sensitivity of cells to doxorubicin in 3D culture conditions. CAPE may be a useful adjunctive compound in the treatment of lung adenocarcinoma.

Overview of Cantharidin and its Analogues.

BACKGROUND: Cantharidin has been categorized as highly toxicant in Chinese medicine. But cantharidin can efficiently treat different types of diseases, such as molluscum contagiosum. While cantharidin is quite useful, unfortunately, due to its side effects, increasing regulations have limited access to this useful therapeutic option. Cantharidin's toxic effects have caused it to fall into disuse for most legitimate medical purposes. Although cantharidin generates effects and its advantages must be realized. Recently, cancer affects people's life more and more. Because cantharidin can treat some cancers, so solutions must be used to reduce side effects. This review aims to describe some its analogues, several efficient methods to inhibit the side effects of cantharidin and pharmacogenomics of cantharidin. METHODS: We searched for research about cantharidin by entering the database. Then evaluated these papers and analyzed their founding, solution, mechanism, etc., and targeted to screen the papers related to the content of our research, and then sorted them out in accordance with the solution, mechanism research and other content. Finally, these content was unified into a framework. RESULTS: Some cantharidin's analogues were found that they show some similar functions to cantharidin and we found that norcantharidin, acylthiourea derivatives, cantharidinamides, anhydride-modified derivatives and other derivatives have less side effects. The modified cantharidin analogues reduce toxicity in hepatocytes. Cantharidin consists of a six-ring and a five-ring, the moiety of oxygen on the six-ring and the anhydride section exhibit biochemical activity. Protein phosphatases are associated with many cellular processes including apoptosis, cell cycle progression and so on. Cantharidin can cause apoptosis and double-stand breakage of DNA. Cantharidin and norcantharidin can efficiently inhibit the activity of mammalian and plant protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) in vivo. Cantharidin inhibits PP5 at the nanomolar level with an IC50 value of 600 nM. PP5 can manage the cellular survival, death, proliferation and other some intracellular biological activities in mammals. After cantharidin's treatment, the level of EtPP5 mRNA expression was downregulated. Their also can be used to inhibit the Glutathione S-transferases (GSTs), angiogenesis and the expression of A549 human lung cancer cells, trigger eryptosis and induced bladder cancer cell apoptosis. We found that using Vitamin C and ginsenosides and translating cantharidin into nanoparticles can minimize the cantharidin side effects in the patients. CONCLUSION: Cantharidin can inhibit various tumor cell lines. Cantharidin causes both DNA single- and double- strand breaks and induces apoptosis. Although cantharidin shows some toxicity for human, its anti-cancer effects should be taken seriously. Several viable methods can help solve this problem. The most important pharmacogenomics of cantharidin is that cantharidin can inhibit PPs, because PPs are associated with many cellular processes. This prospect is very broad and needs to continue studying.

Cantharidin inhibits competitively heme-Fe(III) binding to the FA1 site of human serum albumin.

Cantharidin, a monoterpene isolated from the insect blister beetle, has long been used as a medicinal agent in the traditional Chinese medicine. Cantharidin inhibits a subgroup of serine/threonine phosphatases, thus inducing cell growth inhibition and cytotoxicity. Cantharidin has anticancer activity in vitro, since it is able of inducing p53-dependent apoptosis and double-strand breakage of DNA in cancer cells. Although the toxicity of cantharidin to the gastrointestinal and urinary tracts prevents its medical use, it is a promising lead compound for chemical modification to develop new anticancer therapeutics. In fact, cantharidin does not cause myelosuppression and displays anticancer activity against cells with a multidrug resistance phenotype. Here, the competitive inhibitory effect of cantharidin on heme-Fe(III) binding to the fatty acid site 1 (FA1) of human serum albumin (HSA) is reported. Docking and molecular dynamics simulations support functional data indicating the preferential binding of cantharidin to the FA1 site of HSA. Present results may be relevant in vivo as HSA could transport cantharidin, which in turn could affect heme-Fe(III) scavenging by HSA.

Asialoglycoprotein receptor-targeted liposomes loaded with a norcantharimide derivative for hepatocyte-selective targeting.

In order to overcome the shortcomings associated with the clinical application of norcantharidin (NCTD), including intense irritation and a short half-life, and to obtain a hepatocyte-selective liposome system with high encapsulation efficiency (EE) and low leakage, we synthesized a C14 alkyl chain norcantharimide derivative of NCTD (2-tetradecylhexahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione, N-14NCTDA). Asialoglycoprotein receptor-targeted, galactosylated liposomes loaded with N-14NCTDA (GAL-Lipo) were prepared by the lipid film hydration method. GAL-Lipo with a satisfactory particle size of approximately 120nm has a higher encapsulation efficiency of more than 98.0%, which is markedly increased compared with NCTD loaded liposomes (EE%=47.6%). In addition, GAL-Lipo remained stable for at least 1 month at 4°C. In cytotoxicity assays, GAL-Lipo demonstrated stronger cytotoxicity effects (IC50=24.58µmolL-1) on Hep G2 cells than free N-14NCTDA (100µmol/L) and conventional liposomes (Con-Lipo, 39.49µmol/L) without the GAL modification. GAL-Lipo can continuously accumulate in Hep G2 cells and be internalized into cells via two pathways, namely caveolin-dependent endocytosis and clathrin-dependent asialoglycoprotein receptors (ASGP-R) mediated endocytosis and produces considerably more significant cellular apoptosis. The results of vivo toxicity studies showed that GAL-Lipo dramatically reduced renal toxicity. In addition, GAL-Lipo has a markedly improved pharmacokinetic profile in vivo and a longer circulation time (AUC=6.700±2.964mgL-1h, t1/2z=1.347±0.519h) than Con-Lipo (AUC=2.319±0.121mgL-1h, t1/2z=0.413±0.238h). In conclusion, N-14NCTDA with an ideal logP is a better alternative for the treatment of primary hepatic carcinoma. GAL-Lipo offers an attractive strategy to specifically target hepatocytes via caveolin-dependent and clathrin-dependent asialoglycoprotein receptor-mediated endocytosis resulting in higher anticancer activity and fewer side-effects.