Norcantharidin induces apoptosis of breast cancer cells: Involvement of activities of mitogen activated protein kinases and signal transducers and activators of transcription

Desmocollin-1 is associated with pro-metastatic phenotype of luminal A breast cancer cells and is modulated by parthenolide

BACKGROUND

Desmocollin-1 (DSC1) is a desmosomal transmembrane glycoprotein that maintains cell-to-cell adhesion. DSC1 was previously associated with lymph node metastasis of luminal A breast tumors and was found to increase migration and invasion of MCF7 cells in vitro. Therefore, we focused on DSC1 role in cellular and molecular mechanisms in luminal A breast cancer and its possible therapeutic modulation.

METHODS

Western blotting was used to select potential inhibitor decreasing DSC1 protein level in MCF7 cell line. Using atomic force microscopy we evaluated effect of DSC1 overexpression and modulation on cell morphology. The LC-MS/MS analysis of total proteome on Orbitrap Lumos and RNA-Seq analysis of total transcriptome on Illumina NextSeq 500 were performed to study the molecular mechanisms associated with DSC1. Pull-down analysis with LC-MS/MS detection was carried out to uncover DSC1 protein interactome in MCF7 cells.

RESULTS

Analysis of DSC1 protein levels in response to selected inhibitors displays significant DSC1 downregulation (p-value ≤ 0.01) in MCF7 cells treated with NF-κB inhibitor parthenolide. Analysis of mechanic cell properties in response to DSC1 overexpression and parthenolide treatment using atomic force microscopy reveals that DSC1 overexpression reduces height of MCF7 cells and conversely, parthenolide decreases cell stiffness of MCF7 cells overexpressing DSC1. The LC-MS/MS total proteome analysis in data-independent acquisition mode shows a strong connection between DSC1 overexpression and increased levels of proteins LACRT and IGFBP5, increased expression of IGFBP5 is confirmed by RNA-Seq. Pathway analysis of proteomics data uncovers enrichment of proliferative MCM_BIOCARTA pathway including CDK2 and MCM2-7 after DSC1 overexpression. Parthenolide decreases expression of LACRT, IGFBP5 and MCM_BIOCARTA pathway specifically in DSC1 overexpressing cells. Pull-down assay identifies DSC1 interactions with cadherin family proteins including DSG2, CDH1, CDH3 and tyrosine kinase receptors HER2 and HER3; parthenolide modulates DSC1-HER3 interaction.

CONCLUSIONS

Our systems biology data indicate that DSC1 is connected to mechanisms of cell cycle regulation in luminal A breast cancer cells, and can be effectively modulated by parthenolide.

Paclitaxel and docetaxel resistance in prostate cancer: Molecular mechanisms and possible therapeutic strategies

Prostate cancer is among most malignant tumors around the world and this urological tumor can be developed as result of genomic mutations and their accumulation during progression towards advanced stage. Due to lack of specific symptoms in early stages of prostate cancer, most cancer patients are diagnosed in advanced stages that tumor cells display low response to chemotherapy. Furthermore, genomic mutations in prostate cancer enhance the aggressiveness of tumor cells. Docetaxel and paclitaxel are suggested as well-known compounds for chemotherapy of prostate tumor and they possess a similar function in cancer therapy that is based on inhibiting depolymerization of microtubules, impairing balance of microtubules and subsequent delay in cell cycle progression. The aim of current review is to highlight mechanisms of paclitaxel and docetaxel resistance in prostate cancer. When oncogenic factors such as CD133 display upregulation and PTEN as tumor-suppressor shows decrease in expression, malignancy of prostate tumor cells enhances and they can induce drug resistance. Furthermore, phytochemicals as anti-tumor compounds have been utilized in suppressing chemoresistance in prostate cancer. Naringenin and lovastatin are among the anti-tumor compounds that have been used for impairing progression of prostate tumor and enhancing drug sensitivity. Moreover, nanostructures such as polymeric micelles and nanobubbles have been utilized in delivery of anti-tumor compounds and decreasing risk of chemoresistance development. These subjects are highlighted in current review to provide new insight for reversing drug resistance in prostate cancer.

Norbornene and Related Structures as Scaffolds in the Search for New Cancer Treatments

The norbornene scaffold has arisen as a promising structure in medicinal chemistry due to its possible therapeutic application in cancer treatment. The development of norbornene-based derivatives as potential chemotherapeutic agents is attracting significant attention. Here, we report an unprecedented review on the recent advances of investigations into the antitumoral efficacy of different compounds, including the abovementioned bicyclic scaffold in their structure, in combination with chemotherapeutic agents or forming metal complexes. The impact that structural modifications to these bicyclic compounds have on the antitumoral properties and the mechanisms by which these norbornene derivatives act are discussed in this review. In addition, the use of norbornene, and its related compounds, encapsulation in nanosystems for its use in cancer therapies is here detailed.

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.

Inhibiting STAT3 signaling pathway by natural products for cancer prevention and therapy: In vitro and in vivo activity and mechanisms of action

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in signal transmission from the plasma membrane to the nucleus, regulating the expression of genes involved in essential cell functions and controlling the processes of cell cycle progression and apoptosis. Thus, STAT3 has been elucidated as a promising target for developing anticancer drugs. Many natural products have been reported to inhibit the STAT3 signaling pathway during the past two decades and have exhibited significant anticancer activities in vitro and in vivo. However, there is no FDA-approved STAT3 inhibitor yet. The major mechanisms of these natural product inhibitors of the STAT3 signaling pathway include targeting the upstream regulators of STAT3, directly binding to the STAT3 SH2 domain and inhibiting its activation, inhibiting STAT3 phosphorylation and/or dimerization, and others. In the present review, we have systematically discussed the development of these natural product inhibitors of STAT3 signaling pathway as well as their in vitro and in vivo anticancer activity and mechanisms of action. Outlooks and perspectives on the associated challenges are provided as well.

Norcantharidin counteracts acquired everolimus resistance in renal cell carcinoma by dual inhibition of mammalian target of rapamycin complex 1 and complex 2 pathways in Vitro

Everolimus, an oral mammalian target of rapamycin complex 1 (mTORC1) inhibitor, presents a therapeutic option in metastatic renal cell carcinoma (RCC) patients who were intolerant to, or previously failed, immune- and vascular endothelial growth factor-targeted therapies. However, the onset of drug resistance limits its clinical use. One possible mechanism underpinning the resistance is that inhibiting mTORC1 by everolimus results in mTORC2-dependent activation of v-Akt murine thymoma viral oncogene (AKT) and upregulation of hypoxia-inducible transcription factors (HIF). Norcantharidin (NCTD) is a demethylated derivative of cantharidin with antitumor properties which is an active ingredient of the traditional Chinese medicine Mylabris. In this study, everolimus-resistant RCC cells (786-O-R) obtained by chronic everolimus treatment revealed higher level of HIF2α and over-activated mTORC2 pathway and NCTD inhibits cell proliferation in both everolimus-resistant and -sensitive RCC cells by arresting cell cycle in G0/G1 phase and reducing cell cycle-related proteins of C-Myc and cyclin D. Furthermore, NCTD shows synergistic anticancer effects combined with everolimus in everolimus-resistant 786-O-R cells. Mechanically, NCTD repressed both mTORC1 and mTORC2 signaling pathways as well as downstream molecular signaling pathways, such as p-4EBP1, p-AKT, HIF1α and HIF2α. Our findings provide sound evidence that combination of NCTD and everolimus is a potential therapeutic strategy for treating RCC and overcoming everolimus resistance by dual inhibition of mTORC1 and mTORC2.

Norcantharidin combined with paclitaxel induces endoplasmic reticulum stress mediated apoptotic effect in prostate cancer cells by targeting SIRT7 expression

Prostate cancer (PCa), an extremely common malignancy in males, is the most prevalent disease in several countries. Norcantharidin (NCTD) has antiproliferation, antimetastasis, apoptosis, and autophagy effects in various tumor cells. Nevertheless, the antitumor effect of NCTD combined with paclitaxel (PTX), a chemotherapeutic drug, in PCa remains unknown. The cell growth, proliferative rate, cell cycle distribution, and cell death were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, colony formation assay, PI staining, and Annexin V/PI staining by flow cytomertry, whereas the mitochondrial membrane potential (MMP) and endoplasmic reticulum (ER) stress was evaluated using the MitoPotential assay and ER-ID red assay. We also evaluated the protein and mRNA expression of SIRTs by Western blotting and qRTPCR assay. Overexpression effectivity was measured by DNA transfection assay. Our study showed that cell viability and proliferative PC3 and DU145 rates were effectively inhibited after NCTD-PTX combination. We also found that NCTD-PTX combination treatment significantly enhance G2/M phase arrest, induction of cell death and ER stress, loss of MMP, and ER- or apoptotic-related protein expression. Furthermore, NCTD-PTX combination treatment was significantly decreasing the protein and mRNA expression of SIRT7 in PCa cells. Combination therapy effectively reduced cell viability, ER stress-mediated apoptosis and p-eIF2α/ATF4/CHOP/cleaved-PARP expression inhibition in SIRT7 overexpression of PCa cells. These results indicate that NCTD combined with PTX induces ER stress-mediated apoptosis of PCa cells by regulating the SIRT7 expression axis. Moreover, combination therapy may become a potential therapeutic strategy against human PCa.

Norcantharidin induces G2/M arrest and apoptosis via activation of ERK and JNK, but not p38 signaling in human renal cell carcinoma ACHN cells

Renal cell carcinoma (RCC) is generally acknowledged as the most resistant primary malignancy unresponsive to conventional radiotherapy and chemotherapy treatments. Norcantharidin (NCTD), a therapeutic compound derived from medicinal plants, has been shown to trigger apoptosis, as well as antimetastatic and antioxidant activities in several tumor cells. However, NCTD's mechanism of antitumor activity in the RCC cell line remains unclear. In this study, we report that NCTD led to a time- and dose-dependent inhibition of cell proliferation. It had also markedly induced apoptosis and G2/M phase cell cycle arrest in a dose-dependent manner by decreasing the expressions of pro-caspase-3, pro-caspase-9, cyclin B1, and pCDC25C while increasing active caspase-3, cleaved-PARP, P21, and pCDC2 levels. Interestingly, NCTD treatment provoked the phosphorylation of extracellular-regulated protein kinase (ERK) and c-Jun-N-terminal kinase (JNK), but not of p38 MAPK. Moreover, SCH772984 and SP600125, ERK and JNK inhibitors, respectively, could partially abolish NCTD-induced apoptosis and G2/M phase cell cycle arrest. Collectively, these findings suggest that NCTD might activate JNK and ERK signaling pathways, consequently inducing apoptosis and G2/M arrest through the modulation of related proteins. This study provided evidence that NCTD is a promising therapeutic drug for the treatment of RCC.

Norcantharidin-blocked ANXA2P2 inhibits fibroblast proliferation by increasing UBAP2L mRNA stability through LIN28B

AIMS

Norcantharidin (NCTD) exhibits antitumor, anti-inflammatory, and anti-fibrosis properties, which makes NCTD an attractive candidate for the treatment of pathological scars. This study was designed to investigate the potential effects of NCTD on fibroblast proliferation and explore the underlying mechanisms.

MATERIALS AND METHODS

First, cell viability and cell apoptosis were evaluated to determine the effects of NCTD on human skin fibroblasts, at 10, 50, and 100 μM. To explore the mechanism, bioinformatics analyses, chromatin immunoprecipitation, RNA immunoprecipitation, and RNA pulldown assays, and luciferase reporter assays were performed to verify the relationships among NCTD, signal transducer and activator of transcription 3 (STAT3), annexin A2 pseudogene 2 (ANXA2P2), and ubiquitin-associated protein 2-like (UBAP2L) mRNA in fibroblasts. Loss-of-function experiments were performed to investigate the roles played by STAT3, ANXA2P2, and UBAP2L in the proliferation and apoptosis of fibroblasts.

KEY FINDINGS

We found that NCTD administration induced fibroblast apoptosis and inhibited fibroblast proliferation in a dose-dependent manner. Mechanistically, NCTD inhibited ANXA2P2 transcription through the inhibition of STAT3 phosphorylation. Subsequently, ANXA2P2 was found to enhance the physical interaction between UBAP2L mRNA and lin-28 homolog B (LIN28B), which increased the stability and levels of UBAP2L mRNA. Loss-of-function assays demonstrated that ANXA2P2 and UBAP2L knockdown induced fibroblast apoptosis and suppressed fibroblast proliferation.

SIGNIFICANCE

In conclusion, we confirmed that NCTD inhibits fibroblast proliferation by inhibiting the STAT3/ANXA2P2/UBAP2L axis, which suggested that NCTD could represent a new candidate for the treatment of pathological scars.

In Vitro and In Vivo Evaluation of SP94 Modified Liposomes Loaded with N-14NCTDA, a Norcantharimide Derivative for Hepatocellular Carcinoma-Targeting

The purpose of this research is to develop a liposomal drug delivery system, which can selectively target hepatocellular carcinoma (HCC) to deliver the antitumor agent N-14NCTDA, a C₁₄ alkyl chain norcantharimide derivative of norcantharidin. N-14NCTDA-loaded liposomes were successfully prepared by lipid membrane hydration and extrusion methods. SP94, a targeting peptide for HCC cells, was attached to the liposomes loaded with N-14NCTDA by the post-insertion method to obtain SP94 modified liposomes (SP94-LPs). SP94-LPs had a significant cytotoxicity against Hep G2 cells with the IC₅₀ of 15.395 ± 0.89 μg/mL, which is lower than that of NCTD-S (IC₅₀ = 20.863 ± 0.56 μg/mL) and GAL-LPs (IC₅₀ = 24.589 ± 1.02 μg/mL). Compared with conventional liposomes (Con-LPs), SP94-LPs showed greater cellular uptake in Hep G2 cells. Likewise, significant tumor suppression was achieved in H22 tumor-bearing mice which were treated with SP94-LPs. The tumor inhibition rate (IRw) of SP94-LPs was 82 ± 0.98%, obviously higher than that of GAL-LPs (69 ± 1.39%), Con-LPs (60 ± 2.78%), and NCTD-S (51 ± 3.67%). SP94-LPs exhibited a significant hepatocellular carcinoma-targeting activity in vitro and in vivo, which will provide a new alternative for hepatocellular carcinoma treatment in future. Graphical Abstract.

How Different Are the Molecular Mechanisms of Nodal and Distant Metastasis in Luminal A Breast Cancer?

Simple Summary

Lymph node status is one of the best prognostic factors in breast cancer, however, its association with distant metastasis is not straightforward. Here we compare molecular mechanisms of nodal and distant metastasis in molecular subtypes of breast cancer, with major focus on luminal A patients. Our results indicate that lymph node positivity is associated with NF-κB and Src pathways and is related to high risk of distant metastasis in luminal A patients. Distant metastasis of lymph node negative tumors is related to cell proliferation control and thrombolysis, whereas distant metastasis of lymph node positive tumors is associated mostly to immune response. These mechanisms vary in other molecular subtypes. Our data indicate that the management of breast cancer and prevention of distant metastasis requires stratified approach based on targeted strategies.

Abstract

Lymph node status is one of the best prognostic factors in breast cancer, however, its association with distant metastasis is not straightforward. Here we compare molecular mechanisms of nodal and distant metastasis in molecular subtypes of breast cancer, with major focus on luminal A patients. We analyze a new cohort of 706 patients (MMCI_706) as well as an independent cohort of 836 primary tumors with full gene expression information (SUPERTAM_HGU133A). We evaluate the risk of distant metastasis, analyze targetable molecular mechanisms in Gene Set Enrichment Analysis and identify relevant inhibitors. Lymph node positivity is generally associated with NF-κB and Src pathways and is related to high risk (OR: 5.062 and 2.401 in MMCI_706 and SUPERTAM_HGU133A, respectively, p < 0.05) of distant metastasis in luminal A patients. However, a part (≤15%) of lymph node negative tumors at the diagnosis develop the distant metastasis which is related to cell proliferation control and thrombolysis. Distant metastasis of lymph node positive patients is mostly associated with immune response. These pro-metastatic mechanisms further vary in other molecular subtypes. Our data indicate that the management of breast cancer and prevention of distant metastasis requires stratified approach based on targeted strategies.

NCTD elicits proapoptotic and antiglycolytic effects on colorectal cancer cells via modulation of Fam46c expression and inhibition of ERK1/2 signaling

Colorectal cancer is a digestive tract malignancy and the third leading cause of cancer‑related mortality worldwide. Norcantharidin (NCTD), the demethylated form of cantharidin, has been reported to possess anticancer properties. Family‑with‑sequence‑similarity‑46c (Fam46c), a non‑canonical poly(A) polymerase, has been reported to be critical in NCTD‑mediated effects in numerous types of cancer, including hepatoma. In the current study, it was found that Fam46c expression was reduced in colorectal cancer tissues and cells. Treatment with NCTD was observed to significantly enhance apoptosis and inhibit glycolysis in colorectal cancer cells. In addition, Fam46c and cleaved caspase 3 expression levels were found to be increased in response to NCTD treatment, in contrast to tumor‑specific pyruvate kinase M2 and phosphorylated ERK expression, which was reduced. Importantly, overexpression of Fam46c exerted similar effects as NCTD treatment on the apoptosis and glycolysis of colorectal cancer cells, whereas Fam46c knockdown strongly attenuated the effect of NCTD. Moreover, epidermal growth factor, which acts as an agonist of ERK1/2 signaling, weakened the effects of NCTD on colorectal cancer cells. Taken together, the results indicated that NCTD promotes apoptosis and suppresses glycolysis in colorectal cancer cells by possibly targeting Fam46c and inhibiting ERK1/2 signaling, hence suggesting that Fam46c may act as a tumor suppressor in colorectal cancer. Thus, the present study identified a novel therapeutic target of NCTD in the clinical treatment of colorectal cancer.

Insight into norcantharidin, a small-molecule synthetic compound with potential multi-target anticancer activities

Norcantharidin (NCTD) is a demethylated derivative of cantharidin, which is an anticancer active ingredient of traditional Chinese medicine, and is currently used clinically as a routine anti-cancer drug in China. Clarifying the anticancer effect and molecular mechanism of NCTD is critical for its clinical application. Here, we summarized the physiological, chemical, pharmacokinetic characteristics and clinical applications of NCTD. Besides, we mainly focus on its potential multi-target anticancer activities and underlying mechanisms, and discuss the problems existing in clinical application and scientific research of NCTD, so as to provide a potential anticancer therapeutic agent for human malignant tumors.

Studies on anti-hepatocarcinoma effect, pharmacokinetics and tissue distribution of carboxymethyl chitosan based norcantharidin conjugates

Aiming to enhance therapeutic efficiency and reduce toxic effect of norcantharidin (NCTD), NCTD-conjugated carboxymethyl chitosan (CMCS) conjugates (CNC) were prepared and evaluated for the treatment of hepatocellular carcinoma. In vitro cellular assays revealed that CNC conjugates possessed potent inhibitory effects on the proliferation and migration of BEL-7402 cells. Besides, CNC could change nuclear morphology of tumor cells. In comparison with free NCTD at equivalent dose, CNC exerted enhanced therapeutic efficiency and diminished systemic toxicity in H22 tumor-bearing mice with a tumor inhibition rate of 56.20%. Further investigation about pharmacokinetics and tissue distribution by high performance liquid chromatography (HPLC) analysis indicated that CNC showed a longer retention time in blood circulation and reduced distribution in heart and kidney tissues, thereby exerting different antitumor efficacy and toxicity compared with free NCTD. Our results suggested that CNC conjugates based on CMCS as polymer carriers might be used as a potential clinical alternative for NCTD in tumor therapy.

Contribution of p38 MAPK Pathway to Norcantharidin-Induced Programmed Cell Death in Human Oral Squamous Cell Carcinoma

Norcantharidin (NCTD), a demethylated analog of cantharidin isolated from blister beetles, has been used as a promising anticancer agent; however, the underlying function of NCTD against human oral squamous cell carcinoma (OSCC) has not been fully understood. Here, this study was aimed to investigate the apoptotic effect and molecular targets of NCTD in human OSCC in vitro and in vivo. The anticancer effects of NCTD and its related molecular mechanisms were evaluated by trypan blue exclusion assay, live/dead assay, western blotting, 4-6-Diamidino-2-Phenylindole (DAPI) staining, flow cytometric analysis, Terminal Deoxynucleotidyl Transferase dUTP Nick end Labeling (TUNEL) assay, and immunohistochemistry. NCTD significantly inhibited cell growth and increased the number of dead cells in HSC-3 and HN22 cell lines. It induced the following apoptotic phenomena: (1) the cleavages of poly (ADP-ribose) polymerase and casepase-3; (2) increase in apoptotic morphological changes (nuclear condensation and fragmentation); (3) increase in annexin V-positive cells or sub-G₁ population of cells. NCTD significantly activated the p38 mitogen-activated protein kinase (MAPK) pathway but inactivated the signal transducer and activator of transcription (STAT)3 pathway. A p38 MAPK inhibitor (SB203580) partially attenuated NCTD-induced programmed cell death (apoptosis) in both cell lines, whereas ectopic overexpression of STAT3 did not affect it. NCTD strongly suppressed tumor growth in the tumor xenograft bearing HSC-3 cells, and the number of TUNEL-positive cells increased in NCTD-treated tumor tissues. In addition, NCTD did not cause any histopathological changes in the liver nor the kidney. NCTD induced programmed cell death via the activation of p38 MAPK in OSCC. Therefore, these results suggest that NCTD could be a potential anticancer drug candidate for the treatment of OSCC.

Norcantharidin combined with Coix seed oil synergistically induces apoptosis and inhibits hepatocellular carcinoma growth by downregulating regulatory T cells accumulation

The immune system plays a critical role in exerts effects in the growth and progression of hepatocellular carcinoma (HCC), which needs interacting approaches for effective therapy. In this study, we have found that the Norcantharidin (NCTD) + Coix lacryma-jobi seed oil (CLSO) combination exhibited more potent antitumor effects in an terms of cytotoxicity and apoptotic induction in human HepG2 and HepG2/ADM cells than NCTD or CLSO alone. In vivo, administration of NCTD+CLSO combinations significantly suppressed the formation of tumor in Hepal-1 hepatoma-bearing mice. Furthermore, we found that the in vitro co-cultures of HepG2 or HepG2/ADM cells with PBMCs from healthy donors led to an increase in the number of CD4 + CD25 + T cells. This increase was down-regulated by the combination effectively. Down-regulation of FoxP3 mRNA and protein expression occurred during the combination in the co-cultures. The amount of Tregs of Hepal-1 hepatoma-bearing mice was significantly decreased in the combination treated group. The combination down-regulated the expression of FoxP3, CTLA-4 and Tregs related cytokine (TGF-β and IL-10) in the serum of tumor bearing mice. Taken together, these results suggest that the most valuable aspect of the NCTD+CLSO combined use improves the anti-tumor activity and regulates tumor infiltrating Tregs.

Norcantharidin induces mitochondrial-dependent apoptosis through Mcl-1 inhibition in human prostate cancer cells

Norcantharidin (NCTD) is the demethylated form of cantharidin that exhibits anticancer potential in many cancer cell types. Recent reports suggest that NCTD targeting ROS/AMPK and DNA replication signaling pathway could be an effective strategy for the treatment of PCa cells. However, supportive evidence is limited to the effect of NCTD that induction of apoptosis through suppression of the Mcl-1. Here, we show that NCTD induced PCa cell apoptosis and triggered caspase activation, which was associated with mitochondria dysfunction. Mechanistic investigations suggested that NCTD modulated the Akt signaling via increased nuclear translocation and interaction with the myeloid cell leukemia-1 (Mcl-1) promoter by FOXO4, resulting in an apoptotic effect. Moreover, miR-320d, which targets Mcl-1, was significantly upregulated after NCTD treatment. Overexpression of miR-320d by NCTD induced mitochondria dysfunction and apoptosis, which was notably attenuated with a miR-320d inhibitor. In vivo xenograft analysis revealed that NCTD significantly reduced tumor growth in mice with PC3 tumor xenografts. Taken together, our results provide new insights into the critical role of NCTD in suppressing Mcl-1 via epigenetic upregulation of miR-320d, resulting in PCa cell apoptosis.

Norcantharidin inhibits IL-6-induced epithelial‑mesenchymal transition via the JAK2/STAT3/TWIST signaling pathway in hepatocellular carcinoma cells

Epithelial-mesenchymal transition (EMT), plays a vital role in hepatocellular carcinoma (HCC) development and metastasis. Norcantharidin (NCTD; 7-oxabicyclo (2.2.1) heptane-2,3-dicarboxylic anhydride) plays anticancer roles in the regulation of tumor cell proliferation, apoptosis and migration. However, the molecular mechanism of HCC EMT and the effects of NCTD in the HCC EMT process have been either poorly elucidated or not studied. In this study, HCC EMT was induced by the treatment of IL-6 and various concentrations of NCTD (0, 30, 60 and 120 µM) were treated with HCC cell lines, HCCLM3 and SMMC-7721. We investigated the effect of NCTD on the invasion of HCC cells by using Transwell assay. Immunofluorescence staining, western blot analysis and quantitative RT-PCR were performed to evaluate the protein and mRNA expression levels of HCC cells. Here, using cell line models, our data demonstrated that interleukin 6 (IL-6) induced EMT through the JAK/STAT3/TWIST pathway in HCC. Moreover, our studies revealed that NCTD markedly inhibited IL-6-induced EMT and cell invasiveness. Signaling studies revealed that NCTD sufficiently suppressed JAK/STAT3/TWIST signaling to reverse the IL-6-promoting effects. Collectively, these data provide evidence for the use of NCTD as a potential anticancer drug in HCC metastatic patients.

FAM46C is critical for the anti-proliferation and pro-apoptotic effects of norcantharidin in hepatocellular carcinoma cells

Norcantharidin (NCTD), a demethylated analog of cantharidin derived from Chinese traditional medicine blister beetle, has been currently used as an anticancer drug for various cancers including hepatocellular carcinoma (HCC). In this study, for a more comprehensive understanding of the targets of NCTD in HCC, next-generation RNA-Seq was utilized. We revealed that the expression of FAM46C, which has been reported as a tumor suppressor for multiple myeloma, was enhanced after NCTD treatment. Re-analysis of TCGA (The Cancer Genome Atlas) LIHC (liver hepatocellular carcinoma) dataset demonstrated that FAM46C expression was significantly lower in HCC tissues than in normal liver tissues. NCTD injection or FAM46C overexpression could mitigate diethylnitrosamine (DEN)-initiated HCC in mice. Ectopic expression of FAM46C in two HCC cell lines, SMCC-7721 and SK-Hep-1, significantly repressed cell proliferation, and increased cells population in G2/M phase and cell apoptotic rate. We also found that FAM46C overexpression caused a notable decrease in Ras expression, MEK1/2 phosphorylation and ERK1/2 phosphorylation. More importantly, FAM46C knockdown significantly weakened the biological effects of NCTD on HCC cells, which suggested NCTD exerted the anticancer functions partially through up-regulating FAM46C. In conclusion, FAM46C, a tumor suppressor for HCC, is important for the anti-proliferation and proapoptotic effects of NCTD.

Norcantharidin Inhibits cell growth by suppressing the expression and phosphorylation of both EGFR and c-Met in human colon cancer cells

BACKGROUND

Norcantharidin (NCTD) is a Chinese FDA approved, chemically synthesized drug for cancer treatment. The effect of NCTD on signaling proteins of EGFR and c-Met was systematically elucidated in current study.

METHODS

Two human colon cancer cell lines, HCT116 and HT29, were used as model systems to investigate the anti-cancer molecular mechanism of NCTD. Cell cycle arrest and early/late apoptosis were analyzed by flow cytometry. The levels of EGFR, phospho-EGFR, c-Met, phospho-c-Met and other related proteins were quantified by western blot analysis.

RESULTS

NCTD induced cell cycle arrest at G2/M phase in both cell lines. The early and late apoptosis was also observed. Further investigation indicated that NCTD suppressed not only the expression of the total EGFR and the phosphorylated EGFR but also the expression of the total c-Met and the phosphorylated c-Met in colon cancer cells. Moreover, EGFR expression could be mostly restored by co-treatment with MG132, a proteasome inhibitor. In addition, NCTD-induced cell death was comparable to that of the anti-cancer drug gefitinib, a tyrosine kinase inhibitor for EGFR, based on the immunoblot analysis of the expressed proteins after the drug treatment.

CONCLUSIONS

NCTD might be a useful and inexpensive drug candidate to substitute for gefitinib to serve the treatment needs of cancer patients.

Norcantharidin induces apoptosis in human prostate cancer cells through both intrinsic and extrinsic pathways

BACKGROUND

Norcantharidin, a modified pure compound from blister beetles, was previously demonstrated to induce apoptosis of cancer cells. This study investigated its anti-cancer activity in prostate cancer cells and the mechanisms involved.

METHODS

Two human prostate cancer cell lines, 22Rv1 and Du145, were treated with norcantharidin at concentrations ranging from 3 to 30μg/ml. Cytotoxic effect of norcantharidin was determined by use of the 3-(4,5-dimethylthiazol-yl)-diphenyl tetrazoliumbromide (MTT) assay. The effects of apoptosis were evaluated by cell death assay, Caspase-3, -8, -9 activity and cytochrome c release. The apoptotic related protein expressions (Bcl-2 family and inhibitor of apoptosis proteins) were determined using western blotting.

RESULTS

An MTT assay revealed that norcantharidin induced cytotoxicity against both prostate cancer cells in dose- and time-dependent manners. Treatment with norcantharidin at 3μg/ml or higher significantly increased oligonucleosomal formation with concomitant appearance of PARP cleavage, implicating the induction of apoptosis. Norcantharidin intrinsically elevated cytosolic cytochrome c levels and activated caspase-3, -8, and -9. Extrinsically, it upregulated the expression of not only the death receptors Fas and DR5 in 22Rv1 cells, but also of RIP and TRADD adaptor proteins in Du145 cells. Mechanistically, norcantharidin increased ratios of pro-/anti-apoptotic proteins and decreased expression of IAP family member proteins, including cIAP1 and survivin, regardless of the distinct status of androgen receptor expression in both cells.

CONCLUSIONS

Norcantharidin exhibited cytotoxicity against 22Rv1 and Du145 prostate cancer cells by inducing both intrinsic and extrinsic apoptotic pathways and could thus potentially be a remedy for prostate cancer.

N-Farnesyloxy-norcantharimide inhibits progression of human leukemic Jurkat T cells through regulation of mitogen-activated protein kinase and interleukin-2 production

This study investigated the anticancer effects of N-farnesyloxy-norcantharimide (NOC15), a newly synthesized norcantharidin (NCTD) analogue, on human leukemic Jurkat T cells and the signaling pathway underlying its effects. We found that the half maximal inhibitory concentration (IC50) of NOC15 on Jurkat T cells is 1.4 μmol/l, which is 11.14-fold (=15.6÷1.4) smaller than the 15.6 μmol/l of NCTD on Jurkat T cells, whereas the IC50 of NOC15 on human normal lymphoblast (HNL) is 207.9 μmol/l, which is 8.17-fold (=1698.0÷207.8) smaller than the 1698.0 μmol/l of NCTD on HNL cells. These results indicated that NOC15 exerts a higher anticancer effect on Jurkat T cells and has higher toxicity toward HNL cells than NCTD. Thus, NOC15 is 1.36-fold (=11.14÷8.17) beneficial as an anticancer agent toward Jurkat T cells compared with NCTD. Moreover, NOC15 can increase the percentage of cells in the sub-G1 phase and reduce the cell viability of Jurkat T cells, stimulate p38 and extracellular signal-regulated protein kinase 1/2 (ERK1/2) of mitogen-activated protein kinases (MAPKs) signaling pathway, and inhibit calcineurin expression and interleukin-2 (IL-2) production. However, NOC15 exerted no effects on the Jun-N-terminal kinase 1/2 (JNK1/2) signaling pathway, the production of IL-8, and tumor necrosis factor-α. We conclude that the anticancer activity of the newly synthesized NOC15 is 1.36-fold beneficial than NCTD as an anticancer agent and that NOC15 can increase the percentage of cells in the sub-G1 phase through the stimulation of p38 and ERK1/2 of the MAPK signaling pathway and the inhibition of calcineurin expression and IL-2 production. The NOC15 may have the potential of being developed into an anticancer agent in the future.

New Norcantharidin Analogs: Synthesis and Anticancer Activity

The reaction of direct condensation between S-ethyl-N-(7-oxabicyclo-[2.2.1]heptane-2,3-dicarbonyl)isothiosemicarbazide (1) and primary amines was used for synthesizing new N-substituted amides of 3-(3-ethylthio-1,2,4-triazol-5-yl)-7-oxabicyclo-[2.2.1]heptane-2-carboxylic acid (2-12) as norcantharadin analogs. Moreover, the anticancer activity of the obtained compounds was studied. Among all compounds, the N-3-methylbutyl amide of 3-(3-ethylthio-1,2,4-triazol-5-yl)-7-oxabicyclo-[2.2.1]heptane-2-carboxylic acid (4) presented selective in vitro toxic and antiproliferative effects against the human hepatoma cell line Hep3B, without affecting normal human liver stellate cells (LX-2 cell line).

N-Farnesyloxy-norcantharimide and N-farnesyl-norcantharimide inhibit the progression of leukemia and increase survival days in a syngeneic mouse leukemia model

This study investigated the anticancer effects of two newly synthesized norcantharidin analogs, N-farnesyloxy-norcantharimide (NOC15) and N-farnesyl-norcantharimide (NC15), in L1210 cells and in a syngeneic mouse leukemia model (L1210 cell line plus DBA/2 mice). We found that the half-maximal inhibitory concentration (IC50) of NOC15 and NC15 on L1210 cells is 1.56 and 2.62 μmol/l, respectively, and that the IC50 of NOC15 and NC15 on human normal lymphoblast is 207.9 and 2569 μmol/l, respectively. In cell cycle analysis, NOC15 could increase the sub-G1 phase, whereas NC15 could induce G2/M arrest. Annexin-V apoptosis assay indicated that both NOC15 and NC15 could induce cell apoptosis. In the syngeneic mouse leukemia model, both NOC15 and NC15 could increase the survival days of mice and decrease the tumor weight. Moreover, both NOC15 and NC15 could retard the increase in peripheral blood leukocyte count due to L1210 cells. In the subcutaneous (s.c.) group, the treatment with NOC15 could retard the decrease in the weight of the liver and the spleen caused by L1210 cells, whereas the treatment with NC15 could retard the decrease in the weight of the spleen caused by L1210 cells. We conclude that the new compounds NOC15 and NC15 have strong anticancer activity and low toxicity both in vitro and in vivo. NOC15 and NC15 may have the potential to be developed into anticancer agents in the future.

Norcantharidin enhances ABT-263-mediated anticancer activity in neuroblastoma cells by upregulation of Noxa

Neuroblastoma is an aggressive childhood disease. Even with intensive conventional treatments, the long term survival rate for children with neuroblastoma remains less than 40%, highlighting the importance of finding new therapies. Bcl-2 family proteins play crucial roles in survival, proliferation and chemotherapeutic resistance of neuroblastoma cells. Therefore, targeting Bcl-2 with small molecule inhibitor ABT-263 could be a novel strategy for treatment of neuroblastoma. However, previous studies indicated that most neuroblastoma cell lines are resistant to ABT-263-mediated apoptosis. Thus, it is crucial to discover approaches that could overcome ABT-263 resistance. In this study, we examined the anticancer activity of ABT-263 in combination with norcantharidin (NCTD), a small-molecule anticancer drug derived from a traditional Chinese medicine, in human malignant neuroblastoma cells. We found that NCTD substantially enhanced ABT-263-mediated apoptosis induction, cell viability inhibition, and clonal formation inhibition in neuroblastoma SH-SY5Y and CHLA-119 cell lines. Moreover, the combination anticancer activity was accompanied by upregulation of Noxa, and was associated with characteristics of mitochondrial apoptosis signaling, such as cytosolic release of cytochrome c, activation of caspase-9,-3, and cleavage of PARP. Notably, we observed that knockdown of Noxa significantly attenuated cell death induction by cotreatment with ABT-263 and NCTD, indicating Noxa essentially contributes to the combination anticancer effect. Collectively, our study demonstrated that NCTD could overcome ABT-263-resistance in neuroblastoma cells, and suggested that combinational treatment of ABT-263 with NCTD might be a novel therapeutic option for children with neuroblastoma.

Norcantharidin, derivative of cantharidin, for cancer stem cells

Cancer stem cells (CSCs) existing in human cancers have been demonstrated to be a major cause of cancer treatment resistance, invasion, metastasis, and relapse. Self-renewal pathways, Wnt/β-catenin, Sonic hedgehog (Shh), and the Notch signaling pathway play critical roles in developing CSCs and lead to angiogenesis, migration, invasion, and metastasis. Multidrug resistance (MDR) is an unfavorable factor causing the failure of treatments against cancer cells. The most important and thoroughly studied mechanism involved in MDR is the active efflux of chemotherapeutic agents through membrane drug transporters. There is growing evidence that Norcantharidin (NCTD), a water-soluble synthetic small molecule derivative of naturally occurring cantharidin from the medicinal insect blister beetle (Mylabris phalerata Pallas), is capable of chemoprevention and tumor inhibition. We summarize investigations into the modulation of self-renewal pathways and MDR in CSCs by NCTD. This review may aid in further investigation of using NCTD to develop more effective strategies for cancer treatment to reduce resistance and recurrence.

Norcantharidin suppresses cell growth and migration with enhanced anticancer activity of gefitinib and cisplatin in human non-small cell lung cancer cells

Norcantharidin is the demethylated analog of cantharidin isolated from blister beetles (Mylabris phalerata Pall.). In this study, we evaluated whether norcantharidin exhibits anticancer effects against the human non-small cell lung cancer cell lines A549 (epidermal growth factor receptor (EGFR) mutation-negative) and PC9 (EGFR mutation-positive). Our results revealed that norcantharidin dose-dependently retards cell growth, arrests cell cycle at G2/M phase, reduces cell migration, and even induces apoptosis at the concentration of 100 µM. Moreover, we found that norcantharidin enhances the anticancer effects of gefitinib and cisplatin. Norcantharidin exhibited similar potency of anticancer effects against the two cell lines with different EGFR mutation status and did not affect EGF-induced EGFR phosphorylation, suggesting that the EGFR signaling may not be the target of norcantharidin. In conclusion, our results suggest that norcantharidin exhibits anticancer effects against non-small cell lung cancer cells in vitro and support its potential as a chemotherapeutic agent for treating non-small cell lung cancer.

Clinical report on transarterial neoadjuvant chemotherapy of malignant fibrous histiocytoma in soft tissue

PURPOSE

To review the experience in transarterial neoadjuvant chemotherapy of malignant fibrous histiocytoma (MFH) in soft tissue and to analyze the factors related to prognosis of MFH in soft tissue.

METHODS

Between September 1999 and December 2011, 101 cases of MFH in soft tissue patients treated by transarterial administration of Cisplatin, Adriamycin and Norcantharidin were divided into primary group and recurrent group, and the clinical documents were reviewed. Nine factors that might affect prognosis such as age, sex, tumor size, tumor site, tumor infiltration depth, recurrence if any, pathological type, histologic grade and histologic response of chemotherapy were analyzed statistically.

RESULTS

The 5-year relapse-free survival rate and the overall survival rate were 70.5 and 75.0 %, respectively, in the primary group; 56.1 and 57.9 %, respectively, in the recurrent group. Univariate analysis (log-rank test) showed that the factors affecting the prognosis were age (P = 0.03), tumor size (P = 0.01), pelvic tumor (P = 0.02), recurrence if any (P = 0.004), histologic grade (P = 0.01), and histologic response to chemotherapy (P = 0.007). Multivariate analysis showed that the major factors affecting prognosis were pelvic tumor (P = 0.01), tumor size (P = 0.002), histologic grade (P = 0.002), recurrence if any (P = 0.0004), and histologic response to chemotherapy (P = 0.008).

CONCLUSION

Transarterial neoadjuvant chemotherapy can significantly increase the curative efficacy of chemotherapy and survival rate in MFH treatment.

Putting the brakes on mammary tumorigenesis: loss of STAT1 predisposes to intraepithelial neoplasias

Multiparous Stat1^−/− mice spontaneously develop mammary tumors with increased incidence: at an average age of 12 months, 55% of the animals suffer from mammary cancer, although the histopathology is heterogeneous. We consistently observed mosaic expression or down-regulation of STAT1 protein in wild-type mammary cancer evolving in the control group. Transplantation experiments show that tumorigenesis in Stat1^−/− mice is partially influenced by impaired CTL mediated tumor surveillance. Additionally, STAT1 exerts an intrinsic tumor suppressing role by controlling and blocking proliferation of the mammary epithelium. Loss of STAT1 in epithelial cells enhances cell growth in both transformed and primary cells. The increased proliferative capacity leads to the loss of structured acini formation in 3D-cultures. Analogous effects were observed when Irf1^−/− epithelial cells were used. Accordingly, the rate of mammary intraepithelial neoplasias (MINs) is increased in Stat1^−/− animals: MINs represent the first step towards mammary tumors. The experiments characterize STAT1/IRF1 as a key growth inhibitory and tumor suppressive signaling pathway that prevents mammary cancer formation by maintaining growth control. Furthermore, they define the loss of STAT1 as a predisposing event via enhanced MIN formation.

Norcantharidin enhances ABT-737-induced apoptosis in hepatocellular carcinoma cells by transcriptional repression of Mcl-1

Small-molecule cell-permeable Bcl-2/Bcl-xL antagonist ABT-737 has recently emerged as a novel cancer therapeutic agent because it potently induces apoptosis in certain cancer cells. However, since ABT-737 binds to Mcl-1 with low affinity, ABT-737-mediated apoptosis signaling is inhibited in hepatocellular carcinoma (HCC) cells and other solid cancer cells due to the elevated expression of Mcl-1. Accordingly, strategies that target Mcl-1 are explored for overcoming ABT-737-resistance. In this study, we reported that Norcantharidin (NCTD), a small-molecule anticancer drug derived from Chinese traditional medicine blister beetle (Mylabris), induced transcriptional repression of Mcl-1 and considerably enhanced ABT-737-triggered cell viability inhibition and apoptosis in multiple HCC cell lines. Moreover, we observed that the enhancement of ABT-737-mediated apoptosis by NCTD was associated with activation of mitochondrial apoptosis signaling pathway, which involved cytosolic release of cytochrome c, cleavage of caspase-9 and caspase-3. Additionally, knockdown of Bax/Bak, the key effectors permeabilizing mitochondrial outer membrane significantly attenuated the enhancement, indicating mitochondrial apoptosis pathway played an essential role in the execution of the apoptosis. Finally, knockdown of Mcl-1 substantially potentiated ABT-737-mediated apoptotic cell death, confirming the potency of Mcl-1 repression by NCTD in enhancing ABT-737-induced apoptosis. These results therefore suggest that combination treatment with NCTD can overcome ABT-737 resistance and enhance ABT-737 therapeutic efficacy in treating human HCC.

Fighting fire with fire: poisonous Chinese herbal medicine for cancer therapy

ETHNOPHARMACOLOGICAL RELEVANCE

Following the known principle of "fighting fire with fire", poisonous Chinese herbal medicine (PCHM) has been historically used in cancer therapies by skilled Chinese practitioners for thousands of years. In fact, most of the marketed natural anti-cancer compounds (e.g., camptothecin derivatives, vinca alkaloids, etc.) are often known in traditional Chinese medicine (TCM) and recorded as poisonous herbs as well. Inspired by the encouraging precedents, significant researches into the potential of novel anticancer drugs from other PCHM-derived natural products have been ongoing for several years and PCHM is increasingly being recognized as a gathering place for promising anti-cancer drugs. The present review aimed at giving a rational understanding of the toxicity of PCHM and, especially, providing the most recent developments on PCHM-derived anti-cancer compounds.

MATERIALS AND METHODS

Information on the toxicity and safety control of PCHM, as well as PCHM-derived anti-cancer compounds, was gathered from the articles, books and monographs published in the past 20 years.

RESULTS

Based on an objective introduction to the CHM toxicity, we clarified the general misconceptions about the safety of CHM and summarized the traditional experiences in dealing with the toxicity. Several PCHM-derived compounds, namely gambogic acid, triptolide, arsenic trioxide, and cantharidin, were selected as representatives, and their traditional usage and mechanism of anti-cancer actions were discussed.

CONCLUSIONS

Natural products derived from PCHM are of extreme importance in devising new drugs and providing unique ideas for the war against cancer. To fully exploit the potential of PCHM in cancer therapy, more attentions are advocated to be focused on their safety evaluation and mechanism exploration.

Antimetastatic effects of norcantharidin on hepatocellular carcinoma by transcriptional inhibition of MMP-9 through modulation of NF-kB activity

BACKGROUND

The rate of morbidity and mortality of hepatocellular carcinoma (HCC) in Taiwan has not lessened because of difficulty in treating tumor metastasis. Norcantharidin (NCTD) is currently used as an anticancer drug for hepatoma, breast cancer, and colorectal adenocarcinoma. NCTD possesses various biological anticancer activities, including apoptosis. However, detailed effects and molecular mechanisms of NCTD on metastasis are unclear. Thus, HCC cells were subjected to treatment with NCTD and then analyzed to determine the effects of NCTD on cell metastasis.

METHODOLOGY/PRINCIPAL FINDINGS

Modified Boyden chamber assays revealed that NCTD treatment inhibited cell migration and invasion capacities of HCC cells substantially. Results of zymography and western blotting showed that activities and protein levels of matrix metalloproteinase-9 (MMP-9) and urokinase plasminogen activator (u-PA) were inhibited by NCTD. Western blot analysis showed that NCTD inhibits phosphorylation of ERK1/2. Testing of mRNA level, quantitative real-time PCR, and promoter assays evaluated the inhibitory effects of NCTD on MMP-9 and u-PA expression in HCC cells. The chromatin immunoprecipitation (ChIP) assay for analyzing the genomic DNA sequences bound to these proteins was reactive to the transcription protein nuclear factor (NF)-kappaB, which was inhibited by NCTD. The expression of NF-kappa B was measured by western blot analysis, which revealed decreased nuclear-factor DNA-binding activity after NCTD treatment.

CONCLUSIONS

NCTD inhibited MMP-9 and u-PA expression through the phosphorylation of ERK1/2 and NF-kappaB signaling pathway which serves as a powerful chemopreventive agent in HCC cell metastasis.

Activity of novel quinoxaline-derived chalcones on in vitro glioma cell proliferation

Gliomas are the most common and devastating tumors of the central nervous system (CNS). Many pieces of evidence point out the relevance of natural compounds for cancer therapy and prevention, including chalcones. In the present study, eight synthetic quinoxaline-derived chalcones, structurally based on the selective PI3Kγ inhibitor AS605240, were evaluated for anti-proliferative activity and viability inhibition using glioma cell lines from human and rat origin (U-138 MG and C6, respectively), at different time-periods of incubation and concentrations. The results revealed that four chalcones (compounds 1, 6, 7 and 8), which present methoxy groups at A-ring, displayed higher efficacies and potencies, being able to inhibit either cell proliferation or viability, in a time- and concentration-dependent manner, with an efficacy that was greater than that seen for the positive control compound AS605240. Flow cytometry analysis demonstrated that incubation of C6 cells with compound 6 led to G1 phase arrest, likely indicating an interference with apoptosis. Furthermore, compound 6 was able to visibly inhibit AKT activation, allied to the stimulation of ERK MAP-kinase. The chalcones tested herein, especially those displaying a methoxy substituent, might well represent promising molecules for the adjuvant treatment of glioma progression.