Cantharidin derivatives from the medicinal insect Mylabris phalerata

Natural Occurring Terpene Cyclic Anhydrides: Biosynthetic Origin and Biological Activities

Cyclic acid anhydride is a not very widespread structure in nature, but with a determining role in natural products possessing this functionality in their skeleton. To the best of our knowledge, no revision of terpenes containing cyclic anhydrides has been previously reported. The result was that more than 100 terpenic cyclic anhydrides and related compounds were found to be in need of being reported. This review has been systematically organized by terpene skeletons, from the smallest to largest, describing their sources and bioactivities. In addition, different biosynthetic pathways for their final oxidations, namely, routes A, B and C, leading to the formation of these heterocyclic natural products, have been proposed. We have also included the most plausible precursors of these natural products, which mostly happened to be present in the same natural source. Some molecules derived from terpene cyclic anhydrides, such as their natural imide derivatives, have also been described due to their significant biological activity. In this sense, special attention has been paid to cantharidin because of its historical relevance and its broad bioactivity. A plausible biosynthesis of cantharidin has been proposed for the first time. Finally, cyclic anhydride structures that were firstly assigned as anhydrides and later corrected have been also described.

Network toxicology, molecular docking technology, and experimental verification revealed the mechanism of cantharidin-induced testicular injury in mice

As a protein kinase inhibitor, cantharidin (CTD) exhibits antitumor activities. However, CTD is highly toxic, thereby limiting clinical applications. Moreover, relatively few studies have investigated CTD-induced reproductive toxicity, thus the underlying mechanism remains unclear. In this study, the toxic effects of CTD on mouse testis were confirmed in vivo and the potential mechanism was predicted by network toxicology (NT) and molecular docking technology. Proteins involved in the signaling pathways and core targets were verified. The results showed that different concentrations of CTD induced weight loss increased the testicular coefficient, and caused obvious pathological damage to testicular cells. The NT results showed that the main targets of CTD-induced testicular injury (TI) included AKT1, Caspase 3, Bcl-2, and Bax. The results of pathway enrichment analysis showed that CTD-induced TI was closely related to apoptosis and the PI3K/AKT and HIF-1 signaling pathways. Molecular docking methods confirmed high affinity between CTD and key targets. Western blot analysis showed that CTD inhibited expression of PI3K, AKT, and the anti-apoptotic protein Bcl-2, while promoting expression of the pro-apoptotic proteins Bax and Caspase 3. These results suggest that CTD-induced TI involves multiple targets and pathways, and the underlying mechanism was associated with inhibition of the apoptosis-related PI3K/AKT signaling pathway.

Novel spirooxindole alkaloid derivatives from the medicinal insect Blaps japanensis and their biological evaluation

Blapspirooxindoles A-C (1-3), three novel spirooxindole alkaloids with a unique spiro[chromane-4,3'-indoline]-2,2'-dione motif, blapcumaranons A and B (4 and 5), two new 2-cumaranon derivatives, blapoxindoles A-J (6-15), ten new oxindole alkaloid derivatives, along with one known compound (16), were isolated from the whole bodies of Blaps japanensis. Their structures including absolute configurations were determined by using spectroscopic, X-ray crystallographic, and computational methods. Compounds 1-11 and 13 exist as racemic mixtures in nature, and their (-)- and (+)-antipodes were separated by chiral HPLC. Biological evaluations of these compounds were determined with multiple assays including anti-tumor, anti-inflammatory, and renal protection activities in vitro. Several compounds displayed effective activity in one or more assays.

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-β1-induced NRK-52e cells.

Sodium cantharidate promotes autophagy in breast cancer cells by inhibiting the PI3K-Akt-mTOR signaling pathway

Sodium cantharidate (SCA) is a derivative of cantharidin obtained by its reaction with alkali. Studies have shown that it inhibits the occurrence and progression of several cancers. However, therapeutic effects of SCA on breast cancer are less well studied. This study aimed to clarify the effect of SCA on breast cancer cells and its mechanism, and to provide a scientific basis for the clinical use of SCA for the treatment of breast cancer. The results of cell counting kit-8, colony formation assay, and 5-ethynyl-2'-deoxyuridine staining showed that SCA inhibited breast cancer cell proliferation. Wound-healing and transwell assays demonstrated that SCA inhibited the migration and invasion of breast cancer cells. Transmission electron microscopy revealed that SCA induced autophagy in breast cancer cells. RNA sequencing technology showed that SCA significantly regulated the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin (PI3K-Akt-mTOR) pathway, which was further verified using western blotting. The inducing effect of SCA on breast cancer autophagy was reversed by the mTOR activator MHY1485. In addition, subcutaneous xenograft experiments confirmed that SCA significantly inhibited tumor growth in vivo. Hematoxylin-eosin, TdT-mediated dUTP nick-end labeling, and immunohistochemical staining indicated that SCA induced tumor cell autophagy and apoptosis in nude mice without causing organ damage. In summary, we found that SCA promoted breast cancer cell apoptosis by inhibiting the PI3K-Akt-mTOR pathway and inducing autophagy.

The potential roles of p53 signaling reactivation in pancreatic cancer therapy

Globally, pancreatic cancer (PC) is a common and highly malignant gastrointestinal tumor that is characterized by an insidious onset and ready metastasis and recurrence. Over recent decades, the incidence of PC has been increasing on an annual basis; however, the pathogenesis of this condition remains enigmatic. PC is not sensitive to radio- or chemotherapy, and except for early surgical resection, there is no curative treatment regime; consequently, the prognosis for patients with PC is extremely poor. Transcription factor p53 is known to play key roles in many important biological processes in vertebrates, including normal cell growth, differentiation, cell cycle progression, senescence, apoptosis, metabolism, and DNA damage repair. However, there is a significant paucity of basic and clinical studies to describe how p53 gene mutations or protein dysfunction facilitate the occurrence, progression, invasion, and resistance to therapy, of malignancies, including PC. Herein, we describe the involvement of p53 signaling reactivation in PC treatment as well as its underlying molecular mechanisms, thereby providing useful insights for targeting p53-related signal pathways in PC therapy.

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.

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.

Sodium cantharidinate, a novel anti-pancreatic cancer agent that activates functional p53

Despite the use of many types of chemotherapies for pancreatic cancer, optimal efficacy has not been obtained so far. Pancreatic cancer shows a high incidence of TP53 mutations, inactivating its tumor suppressor activity. In this study, we identified sodium cantharidinate as a novel, potential anti-pancreatic cancer agent that activates p53 function. Sodium cantharidinate reduced the viability of pancreatic cancer cells, including the human primary pancreatic cancer cells, PANC-1, AsPC-1, SW1990 and BXPC-3, in a dose-dependent manner. Sodium cantharidinate induced apoptosis and DNA damage of pancreatic cancer cells. Furthermore, proteome-wide sequencing analysis detected a marked perturbation in p53 signaling pathway on PANC-1 cells upon sodium cantharidinate. Consistent with the previous results, sodium cantharidinate treatment decreased Bcl-2 and mitochondrial cytochrome-c protein expression, as well as phosphorylation of MDM2; meanwhile, it increased the levels of cleaved-caspase-3, cleaved-caspase-9, cleaved-PARP, Bax, and phosphorylated p53, thus inducing the apoptosis of pancreatic cancer cells. The p53-activating effect of sodium cantharidinate was strongly abrogated by treatment with TP53-targeting shRNA. Moreover, sodium cantharidinate inhibited neoplasm growth via the JAK2-STAT3 pathway, which was inhibited by shRNA-TP53 and triggered by combination with gemcitabine. Combination therapy indicated that sodium cantharidinate and gemcitabine synergistically reduced ex vivo and in vivo growth of pancreatic neoplasm. Further docking studies revealed the different binding fates of sodium cantharidinate to activate wild-type p53 function. Thus, sodium cantharidinate could be a potential agent with promising anti-pancreatic cancer efficacy.

Methyl-Cantharidimide (MCA) Has Anticancer Efficacy in ABCB1- and ABCG2-Overexpressing and Cisplatin Resistant Cancer Cells

In this study, we investigated the efficacy of methyl-cantharidimide (MCA), a cantharidin (CTD) analog, as an anticancer drug, in cancer cells overexpressing either ABCB1 or ABCG2 transporters and in cisplatin-resistant cancer cells. The results indicated that: (i) MCA was efficacious in the ABCB1-overexpressing cell line, KB-C2, and the ABCB1-gene-transfected cell line, HEK293/ABCB1 (IC50 from 6.37 to 8.44 mM); (ii) MCA was also efficacious in the ABCG2-overexpressing cell line, NCI-H460/MX20, and the ABCG2-gene-transfected cell lines, HEK293/ABCG2-482-R2, HEK293/ABCG2-482-G2, and the HEK293/ABCG2-482-T7 cell lines (IC50 from 6.37 to 9.70 mM); (iii) MCA was efficacious in the cisplatin resistant cancer cell lines, KCP-4 and BEL-7404/CP20 (IC50 values from 7.05 to 8.16 mM); (iv) MCA (up to 16 mM) induced apoptosis in both BEL-7404 and BEL-7404/CP20 cancer cells; (v) MCA arrested both BEL-7404 and BEL-7404/CP20 cancer cells in the G0/G1 phase of the cell cycle; (vi) MCA (8 mM) upregulated the expression level of the protein, unc-5 netrin receptor B (UNC5B) in HepG2 and BEL-7404 cancer cells. Overall, our results indicated that MCA's efficacy in ABCB1- and ABCG2-overexpressing and cisplatin resistant cancer cells is due to the induction of apoptosis and cell cycle arrest in the G0/G1 phase.

Zoopharmacology: A Way to Discover New Cancer Treatments

Zoopharmacognosy is the multidisciplinary approach of the self-medication behavior of many kinds of animals. Recent studies showed the presence of antitumoral secondary metabolites in some of the plants employed by animals and their use for the same therapeutic purposes in humans. Other related and sometimes confused term is Zootherapy, which consists on the employment of animal parts and/or their by-products such as toxins, venoms, etc., to treat different human ailments. Therefore, the aim of this work is to provide a brief insight for the use of Zoopharmacology (comprising Zoopharmacognosy and Zootherapy) as new paths to discover drugs studying animal behavior and/or using compounds derived from animals. This work is focused on the approaches related to cancer, in order to propose a new promising line of research to overcome multidrug resistance (MDR). This novel subject will encourage the use of new alternative prospective ways to find new medicines.

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.

Methyl-Cantharidimide Inhibits Growth of Human Hepatocellular Carcinoma Cells by Inducing Cell Cycle Arrest and Promoting Apoptosis

Methyl-Cantharidimide (MCA) is a derivative of cantharidin which has potential anticancer activity. This study investigates the effect of MCA on the growth and metastasis of human hepatocellular carcinoma (HCC) cells. Human HCC HepG2 and Hep3B2.1-7 cells, and normal hepatocytes (L02) were treated with a series of concentrations of MCA. The inhibition ability of these cells was examined by CCK-8 assay. Cell cycle and cell apoptosis were determined using Flow Cytometry. The effect of MCA on cell migration and invasion was evaluated through scratch wound healing and transwell migration assays. Furthermore, Western blot was used to evaluate biomarkers associated with cell cycle and apoptosis. It was found that: (i) MCA inhibited cell proliferation in HCC cells in a dose- and time-dependent manner, especially in HepG2 cells; (ii) MCA arrested HCC cells in G-1 phase cell cycle; (iii) MCA induced HCC cells apoptosis; (iv) MCA inhibited the migration ability of HCC cells; and (v) MCA treatment significantly increased cleaved-caspase3 and decreased NF-κB protein in HCC cells. These results suggest that MCA has cytotoxic effect on HCC cells by inducing cell cycle arrest and promoting apoptosis. MCA could be developed as an previous anticancer drug for the treatment of human hepatocellular carcinoma.

Effects of adjuvant traditional Chinese medicine therapy on long-term survival in patients with hepatocellular carcinoma

BACKGROUND

Many patients with hepatocellular carcinoma (HCC) in Asian countries seek adjuvant therapy with traditional Chinese medicine (TCM). This study aims to explore the benefits of TCM therapy in the long-term survival of patients with hepatocellular carcinoma in China.

PATIENTS AND METHODS

In total, 3483 patients with HCC admitted to the Beijing Ditan Hospital of Capital Medical University were enrolled in this study. We used 1:1 frequency matching by sex, age, diagnosis time, Barcelona Clinic Liver Cancer staging, and type of treatments to compare the TCM users (n = 526) and non-TCM users (n = 526). A Cox multivariate regression model was employed to evaluate the effects of TCM therapy on the HR value and Kaplan-Meier survival curve for mortality risk in HCC patients. A log-rank test was performed to analyze the effect of TCM therapy on the survival time of HCC patients.

RESULTS

The Cox multivariate analysis indicated that TCM therapy was an independent protective factor for 5-year survival in patients with HCC (adjusted HR = 0.46, 95% CI 0.40-0.52, p < 0.0001). The Kaplan-Meier curve also showed that after PS matching, TCM users had a higher overall survival rate and a higher progression-free survival rate than non-TCM users. TCM users, regardless of the classification of etiology, tumor stage, liver function level, or type of treatment, all benefited significantly from TCM therapy. In addition, it was found that the most commonly used Chinese patent medications are Fufang Banmao Capsule, Huaier Granule, and Jinlong Capsule.

CONCLUSION

Using traditional Chinese medications as adjuvant therapy can probably prolong median survival time and improve the overall survival among patients with HCC. Further scientific studies and clinical trials are needed to examine the efficiency and safety.