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.

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.

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.

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.

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.

Cantharis by photosynthetic bacteria biotransformation: Reduced toxicity and improved antitumor efficacy.

ETHNOPHARMACOLOGICAL RELEVANCE: The blister beetle, also known as Mylabris cichorii, is not only widely used in clinical applications in Chinese anticancer medicine, but is also one of the main ingredients in a variety of traditional Chinese medicinal preparations with anticancer activity. However, the strong toxicity exhibited by this beetle species limits its clinical applicability, with the photosynthetic bacteria featuring a strong biological conversion function. Therefore, in this study we explore the use of photosynthetic bacteria for bioconversion of the blister beetle in order to reduce the toxicity and in effort to enhance the overall antitumor effect. METHODS AND RESULTS: In the first set of experiments, we utilized an orthogonal experimental design to optimize the culture medium of photosynthetic bacteria. Concurrently, the growth curve of photosynthetic bacteria was used to determine the inoculation amount of the photosynthetic bacteria and the safe concentration of cantharis. Through antitumor activity experiments conducted in vitro we found that the inhibition rate increased through cantharis by PSB biotransformation of HepG2, A549 and BEL-7406 cells. Furthermore, through acute toxicity tests in mice it was found that the blister beetle water extraction liquid exhibits a LD50 value of 1383mg/kg, while the blister beetle transformation liquid exhibits a LD50 value of 206mg/kg. The LD50 value of the blister beetle water extract was found to be 6.7 times higher than the transformation liquid, thus demonstrating that the toxicity of cantharis by PSB biotransformation may be decreased. More strikingly, decreased toxicity was observed in the mouse liver and in pathological sections of the kidneys after transformation. CONCLUSIONS: In this paper we demonstrate for the first time that PSB bioconversion of the blister beetle is able to reduce the toxicity of a common method used in anticancer treatments as part of the principles in traditional Chinese medicine and may therefore improve antitumor activity in vitro.

Crystal structures and mutagenesis of PPP-family ser/thr protein phosphatases elucidate the selectivity of cantharidin and novel norcantharidin-based inhibitors of PP5C.

Cantharidin is a natural toxin and an active constituent in a traditional Chinese medicine used to treat tumors. Cantharidin acts as a semi-selective inhibitor of PPP-family ser/thr protein phosphatases. Despite sharing a common catalytic mechanism and marked structural similarity with PP1C, PP2AC and PP5C, human PP4C was found to be insensitive to the inhibitory activity of cantharidin. To explore the molecular basis for this selectivity, we synthesized and tested novel C5/C6-derivatives designed from quantum-based modeling of the interactions revealed in the co-crystal structures of PP5C in complex with cantharidin. Structure-activity relationship studies and analysis of high-resolution (1.25Å) PP5C-inhibitor co-crystal structures reveal close contacts between the inhibitor bridgehead oxygen and both a catalytic metal ion and a non-catalytic phenylalanine residue, the latter of which is substituted by tryptophan in PP4C. Quantum chemistry calculations predicted that steric clashes with the bulkier tryptophan side chain in PP4C would force all cantharidin-based inhibitors into an unfavorable binding mode, disrupting the strong coordination of active site metal ions observed in the PP5C co-crystal structures, thereby rendering PP4C insensitive to the inhibitors. This prediction was confirmed by inhibition studies employing native human PP4C. Mutation of PP5C (F446W) and PP1C (F257W), to mimic the PP4C active site, resulted in markedly suppressed sensitivity to cantharidin. These observations provide insight into the structural basis for the natural selectivity of cantharidin and provide an avenue for PP4C deselection. The novel crystal structures also provide insight into interactions that provide increased selectivity of the C5/C6 modifications for PP5C versus other PPP-family phosphatases.

De Novo Transcriptome and Expression Profile Analysis to Reveal Genes and Pathways Potentially Involved in Cantharidin Biosynthesis in the Blister Beetle Mylabris cichorii.

The dried body of Mylabris cichorii is well-known Chinese traditional medicine. The sesquiterpenoid cantharidin, which is secreted mostly by adult male beetles, has recently been used as an anti-cancer drug. However, little is known about the mechanisms of cantharidin biosynthesis. Furthermore, there is currently no genomic or transcriptomic information for M. cichorii. In this study, we performed de novo assembly transcriptome of M. cichorii using the Illumina Hiseq2000. A single run produced 9.19 Gb of clean nucleotides comprising 29,247 sequences, including 23,739 annotated sequences (about 81%). We also constructed two expression profile libraries (20-25 day-old adult males and 20-25 day-old adult females) and discovered 2,465 significantly differentially-expressed genes. Putative genes and pathways involved in the biosynthesis of cantharidin were then characterized. We also found that cantharidin biosynthesis in M. cichorii might only occur via the mevalonate (MVA) pathway, not via the methylerythritol 4-phosphate/deoxyxylulose 5-phosphate (MEP/DOXP) pathway or a mixture of these. Besides, we considered that cantharidin biosynthesis might be related to the juvenile hormone (JH) biosynthesis or degradation. The results of transcriptome and expression profiling analysis provide a comprehensive sequence resource for M. cichorii that could facilitate the in-depth study of candidate genes and pathways involved in cantharidin biosynthesis, and may thus help to improve our understanding of the mechanisms of cantharidin biosynthesis in blister beetles.

[Stability of cantharidin and cantharidic acid in Mylabris aqueous solution].

To investigate the stability and the conversion rules of cantharidin and cantharidic acid contained in the Mylabris aqueous solution under different conditions. The contents of cantharidin and cantharidic acid under different conditions (pH, temperature and light) were determined by HPLC-TQ-MS. The results showed that the content of cantharidin was gradually decreased with the rising of pH value, while on the contrary, the content of cantharidic acid was increased gradually; after Mylabris aqueous solution with different pH values were placed at 25, 40 ℃ and 25 ℃ respectively for lighting for 90 days, the samples were collected for analysis. The results showed the contents of cantharidin and cantharidic acid were changed greatly in the first 10 days, mainly including the decrease of cantharidic acid and increase of cantharidin when the solution was acidic, and the increase of cantharidic acid and decrease of cantharidin when the solution was alkaline. After that, the contents of the above two components basically remained stable. This study revealed that pH was the main factor to affect the contents of cantharidin and cantharidic acid, and they could be converted into each other with the changes of pH value. High temperature and light can accelerate the speed of achieving such balance. The study can provide certain reference for the quality control of the medicines using the Mylabris as raw material.

The natural compound cantharidin induces cancer cell death through inhibition of heat shock protein 70 (HSP70) and Bcl-2-associated athanogene domain 3 (BAG3) expression by blocking heat shock factor 1 (HSF1) binding to promoters.

Heat shock factor 1 (HSF1) enhances the survival of cancer cells under various stresses. The knock-out of HSF1 impairs cancer formation and progression, suggesting that HSF1 is a promising therapeutic target. To identify inhibitors of HSF1 activity, we performed cell-based screening with a library of marketed and experimental drugs and identified cantharidin as an HSF1 inhibitor. Cantharidin is a potent antitumor agent from traditional Chinese medicine. Cantharidin inhibited heat shock-induced luciferase activity with an IC50 of 4.2 µm. In contrast, cantharidin did not inhibit NF-κB luciferase reporter activity, demonstrating that cantharidin is not a general transcription inhibitor. When the HCT-116 colorectal cancer cells were exposed to heat shock in the presence of cantharidin, the induction of HSF1 downstream target proteins, such as HSP70 and BAG3 (Bcl-2-associated athanogene domain 3), was suppressed. HSP70 and its co-chaperone BAG3 have been reported to protect cells from apoptosis by stabilizing anti-apoptotic Bcl-2 family proteins. As expected, treating HCT-116 cancer cells with cantharidin significantly decreased the amounts of BCL-2, BCL-xL, and MCL-1 protein and induced apoptotic cell death. Chromatin immunoprecipitation analysis showed that cantharidin inhibited the binding of HSF1 to the HSP70 promoter and subsequently blocked HSF1-dependent p-TEFb recruitment. Therefore, the p-TEFb-dependent phosphorylation of the C-terminal domain of RNA polymerase II was blocked, arresting transcription at the elongation step. Protein phosphatase 2A inhibition with PP2CA siRNA or okadaic acid did not block HSF1 activity, suggesting that cantharidin inhibits HSF1 in a protein phosphatase 2A-independent manner. We show for the first time that cantharidin inhibits HSF1 transcriptional activity.

Cantharidin as an antitumor agent: a retrospective review.

This review summarizes the progress that has been made recently in the medicinal chemistry of cantharidin, a potent antitumor agent from traditional Chinese medicine. Thousands of analogs have been synthesized on the basis of cantharidin, a part of which shows excellent properties, in particular, norcantharidin and norcantharimide. Despite the enormous efforts made, the intriguing bioactivities, mechanism, indications, and their interplay are still ill-defined. This review provides our up-to-date understanding in connection with the therapeutic use, mechanism, structure-activity relationship (SAR) and interesting properties of cantharidin analogs. Considerable development in the design of cantharidin analogs, in combination with mechanistic studies, has laid a foundation for transforming novel antitumor drugs into the clinic.

Scutellaria baicalensis alleviates cantharidin-induced rat hemorrhagic cystitis through inhibition of cyclooxygenase-2 overexpression.

Cantharidin, an active component in mylabris, is used in traditional Chinese medicine (TCM) to treat scabies and hepatoma, but accompanied by hemorrhagic cystitis. Evidence shows that cantharidin induces human bladder carcinoma cell death through COX-2 overexpression in vitro. In TCM, Scutellaria baicalensis is usually used to cure mylabris-induced hematuria. This work was undertaken to determine the mechanisms of cantharidin-induced rat hemorrhagic cystitis and explore the uroprotective effect of S. baicalensis. In vitro results showed cantharidin could induce cytotoxicity through prostaglandin (PG)E2 overproduction of T24 cells. Boiling-water extract of S. baicalensis (SB-WE) could significantly inhibit PGE2 production and COX-2 expression in lipo-polysaccharide-induced RAW 264.7 cells, indicating obvious anti-inflammatory abilities. In vivo results indicated that cantharidin caused rat hemorrhagic cystitis with hematuria via c-Fos and COX-2 overexpression. SB-WE was given orally to cantharidin-treated rats, whereby hematuria level, elevated PGE2 and COX-2 protein overexpression were significantly and dose-dependently inhibited by SB-WE. The anti-inflammatory components of SB-WE are baicalin and wogonin, whose contents were 200.95 ± 2.00 and 31.93 ± 0.26 µg/mg, respectively. In conclusion, cantharidin induces rat cystitis through c-Fos and COX-2 over-expression and S. baicalensis can prevent the resulting hematuria because of its anti-inflammatory effects.

[Preparation and characterization of non-ionic surfactant vesicle of cantharidin].

OBJECTIVE: To study the preparation of cantharidin entrapped non-ionic surfactant vesicle (noisome)and evaluate its quality. METHOD: The niosome loaded with cantharidin was prepared using injection method by non-ionic surfactants as the carrier. An centrifugation separation method and HPLC analysis method of the cantharidin were established to detect the entrapment efficiency. The optimum preparation technology was established by a orthogonal experiment. The morphology, and particle size were studied to evaluate the preparation. RESULT: The average size of niosomes were (209. 8 +/- 0.5) nm. The entrapment efficiency of the CTD-NS was (27.5% +/- 2.0%) and Zeta potential was (41.5 +/- 0.65) mV. CONCLUSION: The preparation of cantharidin noisome by TweenA and SpanB is practicable and successful. These experiments can be the basement of developing targeting drug delivery system.

Three novel cantharidin-related compounds from the Chinese blister beetle, Mylabris phalerata Pall.

Three novel cantharidin analogues were isolated from the Chinese blister beetle, Mylabris phalerata PALL. (Meloidae), which has been used in traditional Chinese medicine for the treatment of cancer. Their structures were determined on the basis of heteronuclear multiple-bond connectivity and nuclear Overhauser effect spectroscopy experiments, and chemical data confirmed them to be so-called cantharimides, in which the anhydride oxygen atoms are replaced by the basic amino acid L-lysine, L-ornithine, and L-arginine moieties.