Cantharidin overcomes IL-2Rα signaling-mediated vorinostat resistance in cutaneous T-cell lymphoma through reactive oxygen species.

BACKGROUND: Vorinostat (SAHA) is a histone deacetylase inhibitor that has shown clinical efficacy against advanced cutaneous T-cell lymphoma (CTCL). However, only a subset of patients with CTCL (30-35%) respond to SAHA and the response is not always sustainable. Thus, understanding the mechanisms underlying evasive resistance in this cancer is an unmet medical need to improve the efficacy of current therapies. PURPOSE: This study aims to identify factors contributing to resistance against SAHA in CTCL and ways to mitigate it. METHODS AND RESULTS: In this study, we demonstrated that attenuated reactive oxygen species (ROS) induces the expression of interleukin (IL)-2Rα, one of the IL-2 receptors, which drives resistance to SAHA in CTCL. We also determined that cantharidin could overcome SAHA resistance to CTCL by blocking IL-2Rα-related signaling via ROS-dependent manner. Mechanistically, accelerated translation of IL-2Rα contributes to excessive IL-2Rα protein formation as a result of reduced ROS levels in SAHA-resistant CTCL. At the same time, amplified IL-2R signals are evidenced by strengthened interaction of IL-2Rß with IL-2Rγ and Janus kinase/signal transducer and activator of transcription molecules, and by increased expression of protein kinase B (AKT)/mTOR and mitogen-activated protein kinase signaling. Moreover, cantharidin, an active constituent of Mylabris used in traditional Chinese medicine, markedly increased ROS levels, and thereby restrained IL-2Rα translation, resulting in suppression of downstream pathways in SAHA-resistant cells. Cantharidin is also found to synergize with SAHA and triggers SAHA-resistant cell death via IL-2R signaling both in vitro and in vivo. CONCLUSION: Our study uncovers a novel molecular mechanism of acquired SAHA resistance and also suggests that using cantharidin is a potential approach to overcome CTCL therapy resistance. Our findings underlie the therapeutic potential of cantharidin in treating CTCL.

In vitro immune-depression and anti-inflammatory activities of cantharidin on gilthead seabream (Sparus aurata) leucocytes activated by λ-carrageenan.

Cantharidin is a natural compound with known therapeutic applications in humans. The aim of this study was to investigate the in vitro effects of cantharidin on gilthead seabream (Sparus aurata) head kidney leucocytes (HKL) stimulated with λ-carrageenan. HKLs were incubated for 24 h with cantharidin (0, 2.5 and 5 µg mL-1) and λ-carrageenan (0 and 1000 µg mL-1). The results showed that HKL viability only decreased by 15.2% after incubated with 5 µg mL-1 of cantharidin and λ-carrageenan. Cantharidin increased the peroxidase activity of HKLs only when incubated in combination with λ-carrageenan. Besides this, cantharidin inhibited the respiratory burst and phagocytic activities. Furthermore, cantharidin induced morphological changes in HKLs (apoptotic and vacuolization signs) that were enhanced when incubated with λ-carrageenan. Considering the analysis of the selected gene expression studied in HKLs [NF-κB subunits (rela, relb, crel, nfkb1, nfkb2), proinflammatory cytokines (il1b, tnfa), anti-inflammatory cytokines (il10, tgfb) and caspases (casp1, casp3, casp8, casp9)], although λ-carrageenan up-regulated the expression of the proinflammatory gene il1b, λ-carrageenan and cantharidin down-regulated its expression in HKLs. In addition, cantharidin up-regulated casp3 and casp9 expression. The casp3 and casp9 gene expression was down-regulated while casp1 gene expression was up-regulated in HKLs incubated with both cantharidin and λ-carrageenan. All the effects of cantharidin are related to its inhibitory effect on protein phosphatases, which induce apoptosis at long exposure times, and minimize the effects of λ-carrageenan. The present results provide detailed insight into the immune-depressive and anti-inflammatory properties of cantharidin on immune cells, which could be of interest to the aquaculture sector.

Cantharidin and sodium fluoride attenuate the negative inotropic effects of carbachol in the isolated human atrium.

Carbachol, an agonist at muscarinic receptors, exerts a negative inotropic effect in human atrium. Carbachol can activate protein phosphatases (PP1 or PP2A). We hypothesized that cantharidin or sodium fluoride, inhibitors of PP1 and PP2A, may attenuate a negative inotropic effect of carbachol. During bypass-surgery trabeculae carneae of human atrial preparations (HAP) were obtained. These trabeculae were mounted in organ baths and electrically stimulated (1 Hz). Force of contraction was measured under isometric conditions. For comparison, we studied isolated electrically stimulated left atrial preparations (LA) from mice. Cantharidin (100 µM) and sodium fluoride (3 mM) increased force of contraction in LA (n = 5-8, p < 0.05) by 113% ± 24.5% and by 100% ± 38.2% and in HAP (n = 13-15, p < 0.05) by 625% ± 169% and by 196% ± 23.5%, respectively. Carbachol (1 µM) alone exerted a rapid transient maximum negative inotropic effect in LA (n = 6) and HAP (n = 14) to 46.9% ± 3.63% and 19.4% ± 3.74%, respectively (p < 0.05). These negative inotropic effects were smaller in LA (n = 4-6) and HAP (n = 9-12) pretreated with 100 µM cantharidin and amounted to 58.0% ± 2.27% and 59.2% ± 6.19% or 3 mM sodium fluoride to 63.7% ± 9.84% and 46.3% ± 5.69%, (p < 0.05). We suggest that carbachol, at least in part, exerts a negative inotropic effect in the human atrium by stimulating the enzymatic activity of PP1 and/or PP2A.

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.

Integrative analysis of the molecular signature of target genes involved in the antitumor effects of cantharidin on hepatocellular carcinoma.

BACKGROUND: Cantharidin (CTD) is the active ingredient of Chinese medicine, which has been traditionally used in multiple cancers treatment, especially in hepatocellular carcinoma (HCC). However, a comprehensive analysis of the CTD-related molecular mechanism is still necessary to understand its functions in HCC treatment. This study aimed to reveal the novel molecular targets and regulatory networks of CTD in HCC. METHODS: A model of H22 tumour-bearing mice was constructed, and the function of CTD in tumour growth was evaluated. An integrated approach of CTD associated transcriptional profiling and biological systems analysis was used to identify key regulators involved in antitumour pathways. The identified differential expression patterns were supported by the results of Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyse, and by protein-protein interaction (PPI) network construction. The relationships between gene expression and tumour immunity were evaluated using Tumour Immune Estimation Resource (TIMER). Prognostic value was analyzed with Kaplan-Meier plotter. RESULTS: In the present study, the therapeutic effect of CTD on HCC was evaluated in vivo. We obtained the CTD-related transcriptional profiles, systematically and intuitively illustrated its possible pharmacological mechanisms in HCC through multiple targets and signalling pathways. These results revealed that the CTD-related differentially expressed genes were involved in autophagy, transcription factors (TFs) related transcriptional regulation, fatty acid metabolism and immune response in HCC. We found that MAPT, TOP2A, CENPF and MEFV were hub genes of CTD targets involved in autophagy regulation. Totally, 14 TFs have been confirmed to be critical for transcriptional regulation, and 33 TF targets were identified as the hub genes in transcriptional mis-regulation pathway in cancer. These TFs were associated with the immune response and immune cell infiltration. In addition, the downregulated genes were significantly enriched in metabolic regulation pathways, especially fatty acid metabolism after CTD treatment. Furthermore, the network of CTD associated miRNAs with these fatty acid metabolism-related targets was constructed in HCC. CONCLUSIONS: Taken together, our results comprehensively elucidated that CTD could act on multiple targets in HCC therapy, affecting autophagy, transcriptional regulation, the immune response and fatty acid metabolism. Our results provide a foundation for the study of the molecular mechanistic of CTD and its clinical application in the treatment of HCC.

Cantharidin-Based Verbenone Derivatives as a Novel Insecticide against Plutella xylostella: Design, Synthesis, Insecticidal Activity Evaluation, and 3D QSAR Study.

The diamondback moth is a detrimental insect pest of brassicaceous crops which was among the first crop insects to be reported as DDT resistant. It has since proven to be significantly resistant to nearly every synthetic insecticide used in the field in many crucifer-producing regions. Due to insecticide control failures in some parts of the world, economically viable crucifer production is now all but impossible. As a result, there has been an increasing effort to identify new compounds with strong pesticidal activity. Cantharidin is one such compound that has been shown to be highly effective against a variety of insect pests. However, its chemical synthesis and potential toxicity to non-target organisms have been a major source of concern. Herein, using rational design approaches, a new series of cantharidin-based verbenone derivatives were synthesized and evaluated for their insecticidal activities against the diamondback moth. Among different compounds screened, compounds 6a, 6h, 6i, and 6q emerged as the most potent compounds exhibiting 100% mortality at a concentration of 100 mg/L after four days. These compounds demonstrated a good anti-feeding effect against the diamondback moth on cabbage leaves. Subsequently, a 3D QSAR study was carried out to identify the key structural features of the synthesized compounds and their correlation with insecticidal activity.

Cantharidin analogue alleviates dextran sulfate sodium-induced colitis in mice by inhibiting the activation of NF-κB signaling.

Ulcerative colitis is a chronic inflammatory disease with a remitting-relapsing clinical course, it has evolved into a global burden given its high incidence worldwide. Cantharidin (CTD) derivatives are a class of compounds whose structures characterized with a 7-oxabicyclo [2.2.1]heptane core. Though potent cytotoxicity CTD and its derivatives showed, their clinical usage as anti-cancer drugs was limited by the toxicity in organs. In order to find new CTD analogues with good activity and lower toxicity, 21 CTD analogues with or without alkynyl substitution at C5 position of 7-oxabicyclo [2.2.1]heptane core were synthesized, some compounds showed better in vitro anti-inflammatory activity compared to CTD and norcantharidin (NCTD). Based on the structure-activity relationship results of in vitro experiment, analogue 3i was chosen for further study. Results from the acute toxicity in mice showed that 3i was hypotoxic with the single-dose MTD (maximum tolerated dose) for oral administration is over 1852 mg/kg, at least 35-fold lower than that of NCTD. Mechanism study indicated that 3i could potently inhibit TNF-α induced activation of NF-κB signaling by down-regulation the expression levels of phosphor- IKK, IκBα, and NF-κB p65, and alleviated dextran sulfate sodium-induced colitis in mice. This study indicated that CTD analogues with alkynyl substitution at C5 position of 7-oxabicyclo [2.2.1]heptane core is a kind of new compounds with good anti-inflammatory activity and lower toxicity in vivo, and might be used as therapeutic agents for inflammatory diseases.

The role of protein phosphatase 2A (PP2A) in the unfolded protein response (UPR) of plants.

Protein phosphatase 2A (PP2A) is a key regulator of plant growth and development, but its role in the endoplasmic reticulum (ER) stress response remains elusive. In this study, we investigated the function of PP2A under ER stress using loss-of-function mutants of ROOTS CURL of NAPHTHYLPHTHALAMIC ACID1 (RCN1), a regulatory A1 subunit isoform of Arabidopsis PP2A. RCN1 mutants (rcn1-1 and rcn1-2) exhibited reduced sensitivity to tunicamycin (TM), an inhibitor of N-linked glycosylation and inducer of unfolded protein response (UPR) gene expression, resulting in less severe effects compared to wild-type plants (Ws-2 and Col-0). TM negatively impacted PP2A activity in Col-0 plants but did not significantly affect rcn1-2 plants. Additionally, TM treatment did not influence the transcription levels of the PP2AA1(RCN1), 2, and 3 genes in Col-0 plants. Cantharidin, a PP2A inhibitor, exacerbated growth defects in rcn1 plants and alleviated TM-induced growth inhibition in Ws-2 and Col-0 plants. Furthermore, cantharidin treatment mitigated TM hypersensitivity in ire1a&b and bzip28&60 mutants. These findings suggest that PP2A activity is essential for an efficient UPR in Arabidopsis.

Cantharidin suppresses hepatocellular carcinoma development by regulating EZH2/H3K27me3-dependent cell cycle progression and antitumour immune response.

BACKGROUND: Cantharidin (CTD) is a major ingredient of cantharis (Mylabris phalerata Pallas) and has been used extensively in traditional Chinese medicines. It has been shown to exhibit anticancer activity in multiple types of cancer, especially hepatocellular carcinoma (HCC). However, there is no systematic study on the relationships among the regulatory networks of its targets in HCC therapy. We focused on histone epigenetic regulation and the influence of CTD on the immune response in HCC. METHODS: We performed a comprehensive analysis of novel CTD targets in HCC based on network pharmacology and RNA-seq approaches. The mRNA levels of target genes were analyzed by qRT-PCR, and the corresponding protein levels were confirmed using enzyme-linked immunosorbent assay (ELISA) and immunohistochemical staining (IHC). ChIP-seq data were visualized by IGV software. The associations of gene transcript levels with the cancer immune score and infiltration level were investigated using TIMER. In vivo, the H22 mouse model of hepatocellular carcinoma was established by treatment with CTD and 5-Fu. The immune cell proportions in the blood were elevated in model mice, as shown by flow cytometry. RESULTS: We identified 58 targets of CTD, which were involved in various pathways in cancer, including apoptosis, the cell cycle, EMT and immune pathways. Moreover, we found that 100 EMT-related genes were differentially expressed after CTD treatment in HCC cells. Interestingly, our results confirmed that the EZH2/H3K27me3 -related cell cycle pathway is a therapeutic target of CTD in antitumour. In addition, we evaluated the influence of CTD on the immune response. Our data showed that the significantly enriched gene sets were positively correlated with the chemokine biosynthetic and chemokine metabolic modules. The proportions of CD4+/CD8 + T cells and B cells were increased, but the proportion of Tregs was decreased after treatment with CTD in vivo. Moreover, we found that the expression of the inflammatory factor and immune checkpoint genes PD-1/PD-L1 was significantly reduced in the mouse model. CONCLUSION: We performed a novel integrated analysis of the potential role of CTD in HCC treatment. Our results provide innovative insight into the mechanism by which cantharidin exerts antitumour effects by regulating target genes expression to mediate apoptosis, EMT, cell cycle progression and the immune response in HCC. Based on the effect of CTD on the immune response, it can be used as a potential effective drug to activate antitumour immunity for the treatment of liver cancer.

Cantharidin increases the force of contraction and protein phosphorylation in isolated human atria.

Cantharidin, an inhibitor of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A), is known to increase the force of contraction and shorten the time to relaxation in human ventricular preparations. We hypothesized that cantharidin has similar positive inotropic effects in human right atrial appendage (RAA) preparations. RAA were obtained during bypass surgery performed on human patients. These trabeculae were mounted in organ baths and electrically stimulated at 1 Hz. For comparison, we studied isolated electrically stimulated left atrial (LA) preparations and isolated spontaneously beating right atrial (RA) preparations from wild-type mice. Cumulatively applied (starting at 10 to 30 µM), cantharidin exerted a positive concentration-dependent inotropic effect that plateaued at 300 µM in the RAA, LA, and RA preparations. This positive inotropic effect was accompanied by a shortening of the time to relaxation in human atrial preparations (HAPs). Notably, cantharidin did not alter the beating rate in the RA preparations. Furthermore, cantharidin (100 µM) increased the phosphorylation state of phospholamban and the inhibitory subunit of troponin I in RAA preparations, which may account for the faster relaxation observed. The generated data indicate that PP1 and/or PP2A play a functional role in human atrial contractility.

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.

Cantharidin and Its Analogue Norcantharidin Inhibit Metastasis-Inducing Genes S100A4 and MACC1.

Colorectal cancer (CRC) is the third most prevalent and second deadliest cancer worldwide. In addition, metastasis directly causes up to 90% of all CRC deaths, highlighting the metastatic burden of the disease. Biomarkers such as S100A4 and MACC1 aid in identifying patients with a high risk of metastasis formation. High expression of S100A4 or MACC1 and to a greater extent the combination of both biomarkers is a predictor for metastasis and poor patient survival in CRC. MACC1 is a tumor-initiating and metastasis-promoting oncogene, whereas S100A4 has not been shown to initiate tumor formation but can, nevertheless, promote malignant tumor growth and metastasis formation. Cantharidin is a natural drug extracted from various blister beetle species, and its demethylated analogue norcantharidin has been shown in several studies to have an anti-cancer and anti-metastatic effect in different cancer entities such as CRC, breast cancer, and lung cancer. The impact of the natural compound cantharidin and norcantharidin on S100A4 and MACC1 gene expression, cancer cell migration, motility, and colony formation in vitro was tested. Here, for the first time, we have demonstrated that cantharidin and norcantharidin are transcriptional inhibitors of S100A4 and MACC1 mRNA expression, protein expression, and motility in CRC cells. Our results clearly indicate that cantharidin and, to a lesser extent, its analogue norcantharidin are promising compounds for efficient anti-metastatic therapy targeting the metastasis-inducing genes S100A4 and MACC1 for personalized medicine for cancer patients.

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.

Exploring Cantharidin and its Analogues as Anticancer Agents: A Review.

BACKGROUND: Cantharidin (CTD) is a highly toxic substance which can be used to treat a variety of cancers. However, the clinical application of CTD is restricted due to the serious side effects. In recent years, screening its analogues, exploring the mechanism of action and using combinatory therapy with certain substances are considered to be feasible methods which can reduce side effects and improve the therapeutic activity of CTD. This review aims to describe SAR (structure-activity relationship) of CTD analogues, CTD induction mechanisms, and combinatory therapy exploration. METHODS: We searched for research about CTD by entering the database. Important information was screened and extracted purposefully, including SAR, mechanisms, methods, etc. Finally, these contents were unified into a framework to form a review. RESULTS: Some CTD analogues with imidazolium salt or double bonds at C-5 and C-6 positions demonstrate good anticancer activity. Through introducing methyl and acetoxy groups at the C-1 or C-4 position, the inhibitory effect of PP was weakened or even inactivated. Removing the two methyl groups of C-2 and C-3 can reduce side effects and improve efficacy. Replacing methyl with fluorine can also improve the activity and reduce toxicity. Water solubility and bioavailability could be improved by opening the five fivemembered anhydride ring to form carboxylic acid, salt, amide, and ester derivatives. The anticancer mechanism can be divided into the following aspects, including inhibiting cell invasion and metastasis, inducing apoptosis, regulating cell cycle and enhancing immunity. The proper formulation of CTD and its analogues (liposomes, nanoparticles and micelles) can improve the targeting of liver cancer and reduce toxic and side effects. CTD combined with anti-angiogenic therapeutics (Ginsenoside Rg3, Bevacizumab, Apatinib and Endostar) showed additive anti-pancreatic cancer effects. CONCLUSION: It was found that the potential mechanism was closely related to multi-channel and multi-target interactions, which provided a guiding direction for the later exploration of new clinical therapeutic applications. However, some detailed mechanisms are still unclear, and more evidence is required to verify. In addition, the new methods to improve the therapeutic potential of CTD and its analogues still need more clinical trials to be tested in the future. This prospect is very broad and worthy of further study.

Inhibition of MZF1/c-MYC Axis by Cantharidin Impairs Cell Proliferation in Glioblastoma.

Myeloid zinc finger 1 (MZF1), also known as zinc finger protein 42, is a zinc finger transcription factor, belonging to the Krüppel-like family that has been implicated in several types of malignancies, including glioblastoma multiforme (GBM). MZF1 is reportedly an oncogenic gene that promotes tumor progression. Moreover, higher expression of MZF1 has been associated with a worse overall survival rate among patients with GBM. Thus, MZF1 may be a promising target for therapeutic interventions. Cantharidin (CTD) has been traditionally used in Chinese medicine to induce apoptosis and inhibit cancer cell proliferation; however, the mechanism by which CTD inhibits cell proliferation remains unclear. In this study, we found that the expression of MZF1 was higher in GBM tissues than in adjacent normal tissues and low-grade gliomas. Additionally, the patient-derived GBM cells and GBM cell lines presented higher levels of MZF1 than normal human astrocytes. We demonstrated that CTD had greater anti-proliferative effects on GBM than a derivative of CTD, norcantharidin (NCTD). MZF1 expression was strongly suppressed by CTD treatment. Furthermore, MZF1 enhanced the proliferation of GBM cells and upregulated the expression of c-MYC, whereas these effects were reversed by CTD treatment. The results of our study suggest that CTD may be a promising therapeutic agent for patients with GBM and suggest a promising direction for further investigation.

Strategies for Solubility and Bioavailability Enhancement and Toxicity Reduction of Norcantharidin.

Cantharidin (CTD) is the main active ingredient isolated from Mylabris, and norcantharidin (NCTD) is a demethylated derivative of CTD, which has similar antitumor activity to CTD and lower toxicity than CTD. However, the clinical use of NCTD is limited due to its poor solubility, low bioavailability, and toxic effects on normal cells. To overcome these shortcomings, researchers have explored a number of strategies, such as chemical structural modifications, microsphere dispersion systems, and nanodrug delivery systems. This review summarizes the structure-activity relationship of NCTD and novel strategies to improve the solubility and bioavailability of NCTD as well as reduce the toxicity. This review can provide evidence for further research of NCTD.

Development of Glycyrrhetinic Acid and Folate Modified Cantharidin Loaded Solid Lipid Nanoparticles for Targeting Hepatocellular Carcinoma.

Cantharidin (CTD) is the major component of anticancer drugs obtained from Mylabris Cichorii and has a good inhibitory effect on several cancers, including hepatocellular carcinoma (HCC) and breast cancer. However, due to its toxicity, oral administration can cause various adverse reactions, limiting its clinical application. The aim of this work was to design glycyrrhetinic acid (GA)- and/or folate (FA)-modified solid lipid nanoparticles (SLNs) for the encapsulation of CTD to target HCC. Four CTD-loaded SLNs (cantharidin solid lipid nanoparticles (CSLNs), glycyrrhetinic acid-modified cantharidin solid lipid nanoparticles (GA-CSLNs), folate-modified cantharidin solid lipid nanoparticles (FA-CSLNs), and glycyrrhetinic acid and folate-modified cantharidin solid lipid nanoparticles (GA-FA-CSLNs)) were prepared by the emulsion ultrasonic dispersion method, and their physicochemical parameters were determined (particle size and distribution, morphology, zeta-potential, entrapment efficiency, drug loading, and hemolysis). Additionally, the antitumor activities of the four SLNs were evaluated comprehensively by tests for cytotoxicity, cell migration, cell cycle, apoptosis, cellular uptake, competition suppression assay, and in vivo tumor suppression assay. Four SLNs showed spherical shapes and mean diameters in the range of 75-110 nm with size dispersion (PDI) within the range of 0.19-0.50 and zeta-potential approximately -10 mV. The entrapment efficiency of CTD in SLNs was higher than 95% for all tested formulations, and no hemolysis was observed. Compared to GA-CSLNs or CSLNs, GA-FA-CSLNs and FA-CSLNs showed stronger cytotoxicity on hepatocellular carcinoma cells (HepG2), and the cytotoxicity of GA-FA-CSLNs on hepatocyte cells (L-02) was remarkably reduced compared with other formulations. GA-FA-CSLNs and FA-CSLNs also increased the inhibition of HepG2 cell migration, and FA-CSLNs had the highest apoptosis rate. The cell cycle results indicated that HepG2 cells were arrested mainly in the S phase and G2/M phase. Analysis of competition inhibition experiments showed that GA and FA ligands had targeted effects on HepG2 cells. The in vivo tumor inhibition experiment showed that GA-FA-CSLNs and FA-CSLNs had excellent tumor inhibition ability-their tumor inhibition rates were 96.46% and 89.92%, respectively. Our results indicate that GA-FA-CSLNs and FA-CSLNs have a promising future in the therapeutic intervention of HCC.

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.

Cantharidin downregulates PSD1 expression and inhibits autophagic flux in yeast cells.

Cantharidin is a terpenoid compound of insect origin, naturally produced by male blister beetles as an antipredatory mechanism. Cantharidin has anticancer properties, which are attributed to its ability to induce cell cycle arrest, DNA damage, MAPK signaling pathway, and apoptosis. Cantharidin has been reported to induce apoptosis in triple-negative breast cancer cells by suppressing autophagy via downregulation of Beclin 1 expression and autophagosome formation. However, it remains unclear which stage of the autophagic pathway is targeted by cantharidin. Herein, we report that yeast cells are sensitive to cantharidin, and external supplementation of ethanolamine (ETA) ameliorates the cytotoxicity. In addition, cantharidin downregulates phosphatidylserine decarboxylase 1 (PSD1) expression. We also report that cantharidin inhibits autophagic flux, and external administration of ETA could rescue this inhibition. Additionally, cotreatment with chloroquine sensitized the autophagy inhibitory effects of cantharidin. We conclude that yeast cells are sensitive to cantharidin due to inhibition of autophagic flux.

Sodium cantharidate induces Apoptosis in breast cancer cells by regulating energy metabolism via the protein phosphatase 5-p53 axis.

Breast cancer is the leading cause of cancer-related death in women worldwide, and despite multiple chemotherapeutic approaches, effective treatment strategies for advanced metastatic breast cancer are still lacking. Metabolic reprogramming is essential for tumor cell growth and propagation, and most cancers, including breast cancer, are accompanied by abnormalities in energy metabolism. Here, we confirmed that sodium cantharidate inhibited cell viability using the Cell Counting Kit-8, clonogenic assay, and Transwell assay. The cell cycle and apoptosis assays indicated that sodium cantharidate induced apoptosis and cell cycle arrest in breast cancer cells. Additionally, proteomic assays, western blots, and metabolic assays revealed that sodium cantharidate converted the metabolic phenotype of breast cancer cells from glycolysis to oxidative phosphorylation. Furthermore, bioinformatics analysis identified possible roles for p53 with respect to the effects of sodium cantharidate on breast cancer cells. Western blot, docking, and phosphatase assays revealed that the regulation of p53 activity by sodium cantharidate was related to its inhibition of protein phosphatase 5 activity. Moreover, sodium cantharidate significantly inhibited tumor growth in tumor-bearing nude mice. In summary, our study provides evidence for the use of sodium cantharidate as an effective and new therapeutic candidate for the treatment of human breast cancer in clinical trials.