Norcantharidin induced DU145 cell apoptosis through ROS-mediated mitochondrial dysfunction and energy depletion

Pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine Sulfonamides as Novel Potential Anticancer Agents: Apoptosis, Oxidative Stress, and Cell Cycle Analysis

The current study continues the evaluation of the anticancer potential of three de novo synthesized pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine sulfonamides-MM129, MM130, and MM131-against human cancer cells of HeLa, HCT 116, PC-3, and BxPC-3 lines. The pro-apoptotic activity of the investigated sulfonamides was shown by observations of changes in the mitochondrial transmembrane potential of the tested cells, externalization of phosphatidylserine on the cellular membrane surface, and cell morphology in microscopic imaging. The computational studies have shown that MM129 exhibited the lowest binding energy values when docked against CDK enzymes. In addition, the highest stability was shown for complexes formed between MM129 and CDK5/8 enzymes. All examined compounds induced cell cycle arrest in the G0/G1 phase in the BxPC-3 and PC-3 cells and simultaneously caused the accumulation of cells in the S phase in the HCT 116 cells. In addition, the increase in the subG1 fraction was observed in PC-3 and HeLa cells. The application of a fluorescent H₂DCFDA probe revealed the high pro-oxidative properties of the tested triazine derivatives, especially MM131. In conclusion, the obtained results suggest that MM129, MM130, and MM131 exhibited strong pro-apoptotic properties towards investigated cells, mainly against the HeLa and HCT 116 cell lines, and high pro-oxidative potential as well. Moreover, it is suggested that the anticancer activity of the tested compounds may be associated with their ability to inhibit CDK enzymes activities.

Gas Flow Shaping via Novel Modular Nozzle System (MoNoS) Augments kINPen-Mediated Toxicity and Immunogenicity in Tumor Organoids

Medical gas plasma is an experimental technology for anticancer therapy. Here, partial gas ionization yielded reactive oxygen and nitrogen species, placing the technique at the heart of applied redox biomedicine. Especially with the gas plasma jet kINPen, anti-tumor efficacy was demonstrated. This study aimed to examine the potential of using passive flow shaping to enhance the medical benefits of atmospheric plasma jets (APPJ). We used an in-house developed, proprietary Modular Nozzle System (MoNoS; patent-pending) to modify the flow properties of a kINPen. MoNoS increased the nominal plasma jet-derived reactive species deposition area and stabilized the air-plasma ratio within the active plasma zone while shielding it from external flow disturbances or gas impurities. At modest flow rates, dynamic pressure reduction (DPR) adapters did not augment reactive species deposition in liquids or tumor cell killing. However, MoNoS operated at kINPen standard argon fluxes significantly improved cancer organoid growth reduction and increased tumor immunogenicity, as seen by elevated calreticulin and heat-shock protein expression, along with a significantly spurred cytokine secretion profile. Moreover, the safe application of MoNoS gas plasma jet adapters was confirmed by their similar-to-superior safety profiles assessed in the hen's egg chorioallantoic membrane (HET-CAM) coagulation and scar formation irritation assay.

Peptide of Trichinella spiralis Infective Larval Extract That Harnesses Growth of Human Hepatoma Cells

Trichinella spiralis, a tissue-dwelling helminth, causes human trichinellosis through ingestion of undercooked meat containing the parasite’s infective larvae. However, benefits from T. spiralis infection have been documented: reduction of allergic diseases, inhibition of collagen-induced arthritis, delay of type 1 diabetes progression, and suppression of cancer cell proliferation. Since conventional cancer treatments have limited and unreliable efficacies with adverse side effects, novel adjunctive therapeutic agents and strategies are needed to enhance the overall treatment outcomes. This study aimed to validate the antitumor activity of T. spiralis infective larval extract (LE) and extricate the parasite-derived antitumor peptide. Extracts of T. spiralis infective larvae harvested from striated muscles of infected mice were prepared and tested for antitumor activity against three types of carcinoma cells: hepatocellular carcinoma HepG2, ovarian cancer SK-OV-3, and lung adenocarcinoma A549. The results showed that LE exerted the greatest antitumor effect on HepG2 cells. Proteomic analysis of the LE revealed 270 proteins. They were classified as cellular components, proteins involved in metabolic processes, and proteins with diverse biological functions. STRING analysis showed that most LE proteins were interconnected and played pivotal roles in various metabolic processes. In silico analysis of anticancer peptides identified three candidates. Antitumor peptide 2 matched the hypothetical protein T01_4238 of T. spiralis and showed a dose-dependent anti-HepG2 effect, not by causing apoptosis or necrosis but by inducing ROS accumulation, leading to inhibition of cell proliferation. The data indicate the potential application of LE-derived antitumor peptide as a complementary agent for human hepatoma treatment.

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.

The impact of mitochondria on cancer treatment resistance

BACKGROUND

The ability of cancer cells to develop treatment resistance is one of the primary factors that prevent successful treatment. Although initially thought to be dysfunctional in cancer, mitochondria are significant players that mediate treatment resistance. Literature indicates that cancer cells reutilize their mitochondria to facilitate cancer progression and treatment resistance. However, the mechanisms by which the mitochondria promote treatment resistance have not yet been fully elucidated.

CONCLUSIONS AND PERSPECTIVES

Here, we describe various means by which mitochondria can promote treatment resistance. For example, mutations in tricarboxylic acid (TCA) cycle enzymes, i.e., fumarate hydratase and isocitrate dehydrogenase, result in the accumulation of the oncometabolites fumarate and 2-hydroxyglutarate, respectively. These oncometabolites may promote treatment resistance by upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, inhibiting the anti-tumor immune response, or promoting angiogenesis. Furthermore, stromal cells can donate intact mitochondria to cancer cells after therapy to restore mitochondrial functionality and facilitate treatment resistance. Targeting mitochondria is, therefore, a feasible strategy that may dampen treatment resistance. Analysis of tumoral DNA may also be used to guide treatment choices. It will indicate whether enzymatic mutations are present in the TCA cycle and, if so, whether the mutations or their downstream signaling pathways can be targeted. This may improve treatment outcomes by inhibiting treatment resistance or promoting the effectiveness of anti-angiogenic agents or immunotherapy.

Reactive oxygen species (ROS) in cancer pathogenesis and therapy: An update on the role of ROS in anticancer action of benzophenanthridine alkaloids

Reactive oxygen species play crucial role in biological homeostasis and pathogenesis of human diseases including cancer. In this line, now it has become evident that ROS level/concentration is a major factor in the growth, progression and stemness of cancer cells. Moreover, cancer cells maintain a delicate balance between ROS and antioxidants to promote pathogenesis and clinical challenges via targeting a battery of signaling pathways converging to cancer hallmarks. Recent findings also entail the therapeutic importance of ROS for the better clinical outcomes in cancer patients as they induce apoptosis and autophagy. Moreover, poor clinical outcomes associated with cancer therapies are the major challenge and use of natural products have been vital in attenuation of these challenges due to their multitargeting potential with less adverse effects. In fact, most available drugs are derived from natural resources, either directly or indirectly and available evidence show the clinical importance of natural products in the management of various diseases, including cancer. ROS play a critical role in the anticancer actions of natural products, particularly phytochemicals. Benzophenanthridine alkaloids of the benzyl isoquinoline family of alkaloids, such as sanguinarine, possess several pharmacological properties and are thus being studied for the treatment of different human diseases, including cancer. In this article, we review recent findings, on how benzophenanthridine alkaloid-induced ROS play a critical role in the attenuation of pathological changes and stemness features associated with human cancers. In addition, we highlight the role of ROS in benzophenanthridine alkaloid-mediated activation of the signaling pathway associated with cancer cell apoptosis and autophagy.

Immunohistochemical Characterisation of GLUT1, MMP3 and NRF2 in Osteosarcoma

Osteosarcoma (OSA) is an aggressive bone malignancy. Unlike many other malignancies, OSA outcomes have not improved in recent decades. One challenge to the development of better diagnostic and therapeutic methods for OSA has been the lack of well characterized experimental model systems. Spontaneous OSA in dogs provides a good model for the disease seen in people and also remains an important veterinary clinical challenge. We recently used RNA sequencing and qRT-PCR to provide a detailed molecular characterization of OSA relative to non-malignant bone in dogs. We identified differential mRNA expression of the solute carrier family 2 member 1 (SLC2A1/GLUT1), matrix metallopeptidase 3 (MMP3) and nuclear factor erythroid 2–related factor 2 (NFE2L2/NRF2) genes in canine OSA tissue in comparison to paired non-tumor tissue. Our present work characterizes protein expression of GLUT1, MMP3 and NRF2 using immunohistochemistry. As these proteins affect key processes such as Wnt activation, heme biosynthesis, glucose transport, understanding their expression and the enriched pathways and gene ontologies enables us to further understand the potential molecular pathways and mechanisms involved in OSA. This study further supports spontaneous OSA in dogs as a model system to inform the development of new methods to diagnose and treat OSA in both dogs and people.

Review on marine sponge alkaloid, aaptamine: A potential antibacterial and anticancer drug

In recent years, biological macromolecules have piqued the interest of researchers owing to their vast variety of biological uses. As a result, the marine sponge is a multicellular heterotrophic parazoan with chemicals for defence against predator assaults, biofouling and microbial diseases. These priceless molecules are known as secondary metabolites, and they are essential for survival in a highly competitive environment. So far, over 5,000 marine natural compounds have been extracted from marine sponges, making them an excellent option for drug formulation. One among them is, aaptamine, a marine alkaloid with a benzo[de][1,6]-napthyridine framework extensively distributed in marine sponges. Due to this reason, aaptamine has been intensively researched for various biological purposes, including cancer and protease inhibition, offering fresh insights into novel treatments. Keeping this in mind, we reviewed the biological significance of the marine sponge alkaloid aaptamine.

Norcantharidin triggers apoptotic cell death in non-small cell lung cancer via a mitophagy-mediated autophagy pathway

Background

Norcantharidin (NCTD) is known to impact on cell progression in many cancers; however, its activity in non-small cell lung cancer (NSCLC) has not yet been characterized. In the present study, we set out to determine the cytotoxic effects of NCTD on the proliferation and apoptosis on A549 cells and their underlying mechanisms.

Methods

NSCLC cell line A549 cells were cultured. A549 cells were treated with different concentrations of NCTD. Cell proliferation was detected by MTT and cell clone formation assay. Cell cycle and apoptosis were detected by flow cytometry. After A549 cells were treated with NCTD for 24 hours, the mitochondrial membrane potential was measured. The protein expression of Bcl-2, Bax, light chain 3 (LC3), et al. was tested by western blot. The expression of LC3 and Tom20 protein was detected by immunofluorescence.

Results

NCTD suppressed the proliferation of NSCLC cells while decreasing mitochondrial membrane potential and inducing G2/M phase arrest. NCTD induced apoptosis, as demonstrated by increased B-cell lymphoma 2/Bcl-2-associated X protein and Bcl-2-associated X protein/myeloid cell leukemia 1 ratios. Aside from autophagy, NCTD induced mitophagy, with an increase in LC3 expression and a decrease in sequestosome 1 (p62) expression in the cytoplasm, accompanied by increased levels of Phospho-adenosine 5'-monophosphate -activated protein kinase (p-AMPK), Phospho-c-Jun NH2-Terminal Kinase (p-JNK), and Phospho-c-jun (p-c-jun) and a decreased level of Phospho-protein kinase B (p-AKT).

Conclusions

This study has elucidated that NCTD restrains NSCLC cell progression via regulation of AMPK/mammalian target of rapamycin (mTOR)/uncoordinated 51-like kinase 1 (ULK1)/JNK pathways. This evidence provides insight into a novel treatment for NSCLC.

Hydroxychloroquine Potentiates Apoptosis Induced by PPARα Antagonist in 786-O Clear Cell Renal Cell Carcinoma Cells Associated with Inhibiting Autophagy

Clear cell renal cell carcinoma (ccRCC) is the major pathological pattern of renal cell carcinoma. The ccRCC cells exhibit a certain degree of inherent drug resistance due to some genetic mutations. In recent years, peroxisome proliferator-activated receptor-α (PPARα) antagonists have been reported as a targeted therapeutic drug capable of inducing apoptosis and cell cycle arrest in the ccRCC cell line. Autophagy, which can be induced by stress in eukaryotic cells, plays a complex role in the proliferation, survival, and death of tumor cells. In our study, we found that the expression of PPARα was low in highly differentiated ccRCC tissues and 786-O cell line but high in poorly differentiated ccRCC tissues. The level of PPARα expression in ccRCC tissues is correlated to the grade of differentiation, but not to the sex or age of ccRCC patients. The findings also revealed that the PPARα antagonist GW6471 can lower cell viability and induce autophagy in the 786-O ccRCC cell line. This autophagy can be inhibited by hydroxychloroquine. When treated with a combination of hydroxychloroquine and GW6471, the viability of the 786-O cells was decreased further when compared to the treatment with GW6471 or hydroxychloroquine alone, and apoptosis was promoted. Meanwhile, when human kidney 2 cells were cotreated with hydroxychloroquine and GW6471, cell viability was only slightly influenced. Hence, our finding indicates that the combination of GW6471 and hydroxychloroquine may constitute a novel and potentially effective treatment for ccRCC. Furthermore, this approach is likely to be safe owing to its minimal effects on normal renal tissues.

Norcantharidin combined with 2-deoxy-d-glucose suppresses the hepatocellular carcinoma cells proliferation and migration

Present study aims to investigate the combined effect of anticancer drug, norcantharidin (NCTD) in combination with glycolytic inhibitor, i.e. 2-deoxy-d-glucose (2-DG) in liver cancer (HepG2 and Hepa 1-6) cells. Cell viability of NCTD and 2-DG exposed cells was determined by MTT assay, whereas, colony-forming efficiency and migration rate was determined by clonogenic assay and wound healing assay, respectively. Nuclear DAPI staining and Annexin V FITC-PI staining were used to study the apoptosis induction in cells. Fluorescence microscopy imaging was performed to detect the intracellular reactive oxygen species (ROS) generation and mitochondrial membrane potential by staining with DCFDA and JC-1 dye, respectively. Cell viability assay revealed that NCTD and 2-DG exposure in combination displays more cytotoxic effect than a single drug. Additionally, cells lose their colony formation efficiency, as well as the reduced migration rate ability was also observed upon combined exposure. Increased nuclear condensation and mitochondrial membrane depolarization are considered as key features for apoptosis induction in cancerous cells. Furthermore, oxidative stress produced in cells due to enhanced intracellular ROS generation is also major probability for cellular damage. Thus, from the initial data it can be concluded that further preclinical studies will be needed to prove the efficacy of NCTD and 2-DG in hepatocellular carcinoma therapy.

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.

ROS in cancer therapy: the bright side of the moon

Reactive oxygen species (ROS) constitute a group of highly reactive molecules that have evolved as regulators of important signaling pathways. It is now well accepted that moderate levels of ROS are required for several cellular functions, including gene expression. The production of ROS is elevated in tumor cells as a consequence of increased metabolic rate, gene mutation and relative hypoxia, and excess ROS are quenched by increased antioxidant enzymatic and nonenzymatic pathways in the same cells. Moderate increases of ROS contribute to several pathologic conditions, among which are tumor promotion and progression, as they are involved in different signaling pathways and induce DNA mutation. However, ROS are also able to trigger programmed cell death (PCD). Our review will emphasize the molecular mechanisms useful for the development of therapeutic strategies that are based on modulating ROS levels to treat cancer. Specifically, we will report on the growing data that highlight the role of ROS generated by different metabolic pathways as Trojan horses to eliminate cancer cells.

Highly reactive molecules called reactive oxygen species (ROS), which at low levels are natural regulators of important signaling pathways in cells, might be recruited to act as “Trojan horses” to kill cancer cells. Researchers in Italy led by Bruno Perillo of the Institute of Food Sciences in Avelllino review the growing evidence suggesting that stimulating production of natural ROS species could become useful in treating cancer. Although ROS production is elevated in cancer cells it can also promote a natural process called programmed cell death. This normally regulates cell turnover, but could be selectively activated to target diseased cells. The authors discuss molecular mechanisms underlying the potential anti-cancer activity of various ROS-producing strategies, including drugs and light-stimulated therapies. They expect modifying the production of ROS to have potential for developing new treatments.

ACSS2/AMPK/PCNA pathway‑driven proliferation and chemoresistance of esophageal squamous carcinoma cells under nutrient stress

Although platinum‑based chemotherapy is the first‑line choice for locally advanced or metastatic esophageal squamous cell carcinoma (ESCC) patients, accelerated recurrence and chemoresistance remain inevitable. New evidence suggests that metabolism reprogramming under stress involves independent processes that are executed with a variety of proteins. This study investigated the functions of nutrient stress (NS)‑mediated acetyl‑CoA synthetase short‑chain family member 2 (ACSS2) in cell proliferation and cisplatin‑resistance and examined its combined effects with proliferating cell nuclear antigen (PCNA), a key regulator of DNA replication and repair. Here, it was demonstrated that under NS, when the AMP‑activated protein kinase (AMPK) pathway was activated, ESCC cells maintained proliferation and chemoresistance was distinctly upregulated as determined by CCK‑8 assay. As determined using immunoblotting and RT‑qPCR, compared with normal esophageal epithelial cells (Het‑1A), ESCC cells were less sensitive to NS and showed increased intracellular levels of ACSS2. Moreover, it was shown that ACSS2 inhibition by siRNA not only greatly interfered with proliferation under NS but also participated in DNA repair after cisplatin treatment via PCNA suppression, and the acceleration of cell death was dependent on the activation of the AMPK pathway as revealed by the Annexin V/PI and TUNEL assay results. Our study identified crosstalk between nutrient supply and chemoresistance that could be exploited therapeutically to target AMPK signaling, and the results suggest ACSS2 as a potential biomarker for identifying higher‑risk patients.

A mechanistic study of the effect of transferrin conjugation on cytotoxicity of targeted liposomes

This study was performed to prepare 5-fluorouracil (5FU) containing targeted liposomes for the safety and efficacy enhancement. Liposomes were prepared using thin layer method and transferrin (Tf) was employed as the targeting ligand. Morphology of 5FU-loaded liposomes was assessed by transmission electron microscopy (TEM). The in vitro cytotoxicity was investigated via MTT assay on HT-29, CT26 and fibroblast cells. Mitochondrial membrane and cell death evaluations were also investigated. Resulted showed that the encapsulation efficiency (EE%) and particle size of the liposomes were 40.12% and 130 nm, respectively. TEM image implied that liposomes were spherical in shape. In cancer cells, targeted liposomes triggered the mitochondrial apoptotic pathway by lower production of reactive oxygen species (ROS) (63.58 vs 84.95 fluorescence intensity), reduced mitochondrial membrane potential and releasing of cytochrome c (68.66 vs 51.13 ng/mL). The results of this study indicated that Tf-targeted 5FU liposomes can be employed as promising nanocarrier for the delivery of drugs to cancer cells.

Causation by Diesel Exhaust Particles of Endothelial Dysfunctions in Cytotoxicity, Pro-inflammation, Permeability, and Apoptosis Induced by ROS Generation

Epidemiological studies suggest that an increase of diesel exhaust particles (DEP) in ambient air corresponds to an increase in hospital-recorded myocardial infarctions within 48 h after exposure. Among the many theories to explain this data are endothelial dysfunction and translocation of DEP into vasculature. The mechanisms for such DEP-induced vascular permeability remain unknown. One of the major mechanisms underlying the effects of DEP is suggested to be oxidative stress. Experiments have shown that DEP induce the generation of reactive oxygen species (ROS), such as superoxide anion and H₂O₂ in the HUVEC tube cells. Transcription factor Nrf2 is translocated to the cell nucleus, where it activates transcription of the antioxidative enzyme HO-1 and sequentially induces the release of vascular permeability factor VEGF-A. Furthermore, a recent study shows that DEP-induced intracellular ROS may cause the release of pro-inflammatory TNF-α and IL-6, which may induce endothelial permeability as well by promoting VEGF-A secretion independently of HO-1 activation. These results demonstrated that the adherens junction molecule, VE-cadherin, becomes redistributed from the membrane at cell-cell borders to the cytoplasm in response to DEP, separating the plasma membranes of adjacent cells. DEP were occasionally found in endothelial cell cytoplasm and in tube lumen. In addition, the induced ROS is cytotoxic to the endothelial tube-like HUVEC. Acute DEP exposure stimulates ATP depletion, followed by depolarization of their actin cytoskeleton, which sequentially inhibits PI3K/Akt activity and induces endothelial apoptosis. Nevertheless, high-dose DEP augments tube cell apoptosis up to 70 % but disrupts the p53 negative regulator Mdm2. In summary, exposure to DEP affects parameters influencing vasculature permeability and viability, i.e., oxidative stress and its upregulated antioxidative and pro-inflammatory responses, which sequentially induce vascular permeability factor, VEGF-A release and disrupt cell-cell junction integrity. While exposure to a low dose of DEP actin triggers cytoskeleton depolarization, reduces PI3K/Akt activity, and induces a p53/Mdm2 feedback loop, a high dose causes apoptosis by depleting Mdm2. Addition of ROS scavenger N-acetyl cysteine suppresses DEP-induced oxidative stress efficiently and reduces subsequent damages by increasing endogenous glutathione.

Norcantharidin enhances antitumor immunity of GM-CSF prostate cancer cells vaccine by inducing apoptosis of regulatory T cells

Norcantharidin (NCTD) is a promising antitumor drug with low toxicity. It was reported to be able to regulate immunity, but the mechanism is not yet clear. Here we explored whether NCTD could enhance the antitumor immunity induced by prostate cancer cell vaccine. The results of the in vitro study showed that NCTD induced apoptosis and inhibited proliferation of regulatory T cells (Tregs). Mechanistic research showed that NCTD inhibited Akt activation and activated FOXO1 transcription, resulting in a pro‐apoptotic effect. The results of the in vivo study showed that more tumor‐infiltrating Tregs existed within peripheral blood and tumor tissue after treatment with the vaccine. Adding NCTD to vaccine treatment could decrease the number of tumor‐infiltrating Tregs and increase the number of CD4⁺ and CD8⁺ T cells. Combination therapy with NCTD and vaccine was more effective in inhibiting tumor growth than the vaccine alone. In general, this is the first report that NCTD could induce apoptosis of Tregs and enhance the vaccine‐induced immunity.

Deregulation of UBE2C-mediated autophagy repression aggravates NSCLC progression

The roles of aberrantly regulated autophagy in human malignancy and the mechanisms that initiate and sustain the repression of autophagy in carcinogenesis are less well defined. Activation of the oncogene UBE2C and repression of autophagy are concurrently underlying the initiation, progression, and metastasis of lung cancer and exploration of essential association of UBE2C with autophagy will confer more options in searching novel molecular therapeutic targets in lung cancer. Here we report that aberrant activation of UBE2C in lung tumors from patients associates with adverse prognosis and enhances cell proliferation, clonogenicity, and invasive growth of NSCLC. UBE2C selectively represses autophagy in NSCLC and disruption of UBE2C-mediated autophagy repression attenuates cell proliferation, clonogenicity, and invasive growth of NSCLC. Autophagy repression is essentially involved in UBE2C-induced cell proliferation, clonogenicity, and invasive growth of NSCLC. Interference of UBE2C-autophagy repression axis by Norcantharidin arrests NSCLC progression. UBE2C is repressed post-transcriptionally via tumor suppressor miR-381 and epitranscriptionally stabilized with maintenance of lower m⁶A level within its mature RNAs due to the upregulation of m⁶A demethylase ALKBH5 in NSCLC. Collectively, our results indicated that deregulated UBE2C-autophagy repression axis drives NSCLC progression which renders varieties of potential molecular targets in cancer therapy of NSCLC.

Hirsutine induces mPTP-dependent apoptosis through ROCK1/PTEN/PI3K/GSK3β pathway in human lung cancer cells

Hirsutine extracted from Uncaria rhynchophylla has been shown to exhibit anti-cancer activity. However, the molecular mechanism by which hirsutine exhibits anti-lung cancer activity remains unclear. In the present study, we showed that hirsutine induces apoptosis in human lung cancer cells via loss of mitochondrial membrane potential (∆ψm), adenosine triphosphate (ATP) depletion, ROS production, as well as cytochrome c release. Dephosphorylation of GSK3β is involved in hirsutine-mediated mitochondrial permeability transition pore (mPTP) opening through ANT1/CypD interaction. Mechanistic study revealed that interruption of ROCK1/PTEN/PI3K/Akt signaling pathway plays a critical role in hirsutine-mediated GSK3β dephosphorylation and mitochondrial apoptosis. Our in vivo study also showed that hirsutine effectively inhibits tumor growth in a A549 xenograft mouse model through ROCK1/PTEN/PI3K/Akt signaling-mediated GSK3β dephosphorylation and apoptosis. Collectively, these findings suggest a hierarchical model in which induction of apoptosis by hirsutine stems primarily from activation of ROCK1 and PTEN, inactivation of PI3K/Akt, leading in turn to GSK3β dephosphorylation and mPTP opening, and culminating in caspase-3 activation and apoptosis. These findings could provide a novel mechanistic basis for the application of hirsutine in the treatment of human lung cancer.

Repression of YAP by NCTD disrupts NSCLC progression

The efficacy of available lung cancer therapeutic interference is significantly limited by various resistance mechanisms to those drugs. Activation of the oncogene YAP underlying the initiation, progression, and metastasis of lung cancer associates with poor prognosis and confers drug resistance against targeted therapy. In this study, we evaluated the specificity of norcantharidin (NCTD) in repressing YAP to inhibit non-small cell lung carcinoma (NSCLC) progression. Our study revealed that YAP signal pathways were aberrantly activated in lung cancer tissues and cells which rendered more proliferative and invasive phenotypes to human lung cancer cells. We confirmed that NCTD specifically repressed YAP signaling pathway to interfere the YAP-mediated non-small cell lung carcinoma progression and metastasis via arresting cell cycle, enhancing apoptosis and inducing senescence. We also found NCTD-mediated repression of YAP decreased epithelial-to-mesenchymal transition (EMT) and reduced the motile and invasive cellular phenotype in vitro via enhancing E-cadherin and decreasing fibronectin/vimentin. Mechanistic investigations revealed that NCTD transcriptionally downregulated YAP and post-translationally modulated the subcellular redistribution of YAP between nucleus and cytoplasm. Collectively, our results indicated that NCTD is a novel therapeutic drug candidate for NSCLC which specifically and sensitively target YAP signal pathway.

Transferrin targeted liposomal 5-fluorouracil induced apoptosis via mitochondria signaling pathway in cancer cells

The purpose of this study was to prepare transferrin (Tf) targeted liposomal 5-Fluorouracil (5FU) to improve the safety and efficacy of the drug. Liposomes were prepared using thin layer method. Morphology of liposomes was characterized by transmission electron microscopy (TEM) and their particle size was also determined. The in vitro cytotoxicity was investigated via MTT assay on HT-29 (as cancer cell) and fibroblast (as normal cell). Moreover, cytotoxicity mechanism of targeted liposomes was determined through the production of reactive oxygen species (ROS), mitochondrial membrane potential (∆Ψ_m) and release of cytochrome c. Results showed that encapsulation efficiency (EE%) was 58.66±0.58 and average size of liposomes was 107nm. Also, nano-particles were spherical as shown by TEM. MTT assay on HT-29 cells revealed the higher cytotoxic activity of targeted liposomes in comparison to free drug and non-targeted liposome. In contrast, comparing with cancer cells, targeted liposomes had no cytotoxic effect on normal cells. In addition, targeted liposomes induced apoptosis through activation of mitochondrial apoptosis pathways, as evidenced by decreased mitochondrial membrane potential and release of cytochrome c. Results of the study indicated that targeted liposomes would provide a potential strategy to treat colon cancer by inducing apoptosis via mitochondria signaling pathway with reducing dose of the drug and resulting fewer side-effects.

Induction of endoplasmic reticulum stress and mitochondrial dysfunction dependent apoptosis signaling pathway in human renal cancer cells by norcantharidin

Previous studies reported that norcantharidin (NCTD) has anti-tumor effects. We investigated the antitumor effects and underlying mechanism of NCTD on human renal cancer in vitro and in vivo. NCTD significantly decreased renal cancer cell viability by induction of apoptosis, as determined by the MTT assay and annexin V/PI staining. NCTD treatment of 786-O and A-498 cells altered the expression of caspase family proteins and PARP. Moreover, NCTD induced mitochondrial depolarization, which was accompanied by an increased level of Bax and decreased levels of Bcl-2 and Mcl-1. NCTD induced endoplasmic reticulum (ER) stress by increasing the expression of Grp78, p-elF2α, ATF4, and CHOP. Pretreatment with an ER stress inhibitor (salubrinal) significantly attenuated the effect of NCTD. NCTD also induced activation of the AKT pathway in 786-O and A-498 cells. Overexpression of AKT partly reversed the effect of NCTD on apoptosis. NCTD treatment led to decreased expression of Bcl-2 and Mcl-1, and increased expression of Bax, cleaved-caspase-9, cleaved-PARP, and p-elF2α. Our in vivo studies demonstrated that NCTD significantly inhibited tumor growth in a nude mouse xenograft model. Taken together, our results suggest that NCTD is a potential anti-tumor agent for treatment of renal carcinoma.

Effect of norcantharidin on the proliferation, apoptosis, and cell cycle of human mesangial cells

AIMS

Norcantharidin (NCTD) regulates immune system function and reduces proteinuria. We sought to investigate the effect of NCTD on proliferation, apoptosis and cell cycle of cultured human mesangial cells (HMC) in vitro.

METHODS

HMC cells were divided into a normal control group, and various concentrations of NCTD group (2.5, 5, 10, 20, or 40 μg/mL). Cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, apoptosis was detected by Annexin V/propidium iodide (PI) assays, and morphological analysis was performed by Hoechest 33258 staining. Finally, cell cycle was analyzed by flow cytometry.

RESULTS

NCTD dose and time dependently inhibits HMC proliferation significantly (p < .05). Apoptosis dose and time dependently increased after NCTD treatment. Cell-cycle analysis revealed that the number of cells in the G2 phase increased significantly, whereas the fraction of cells in the S phase decreased, especially 24 h after 5 μg/ml NCTD treatment.

CONCLUSION

NCTD inhibits HMC cell proliferation, induces apoptosis, and affects the cell cycle.

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.

Insects: an underrepresented resource for the discovery of biologically active natural products

Nature has been the source of life-changing and -saving medications for centuries. Aspirin, penicillin and morphine are prime examples of Nature׳s gifts to medicine. These discoveries catalyzed the field of natural product drug discovery which has mostly focused on plants. However, insects have more than twice the number of species and entomotherapy has been in practice for as long as and often in conjunction with medicinal plants and is an important alternative to modern medicine in many parts of the world. Herein, an overview of current traditional medicinal applications of insects and characterization of isolated biologically active molecules starting from approximately 2010 is presented. Insect natural products reviewed were isolated from ants, bees, wasps, beetles, cockroaches, termites, flies, true bugs, moths and more. Biological activities of these natural products from insects include antimicrobial, antifungal, antiviral, anticancer, antioxidant, anti-inflammatory and immunomodulatory effects.

ROS-modulated therapeutic approaches in cancer treatment

PURPOSE

Reactive oxygen species (ROS) are produced in cancer cells as a result of increased metabolic rate, dysfunction of mitochondria, elevated cell signaling, expression of oncogenes and increased peroxisome activities. Certain level of ROS is required by cancer cells, above or below which lead to cytotoxicity in cancer cells. This biochemical aspect can be exploited to develop novel therapeutic agents to preferentially and selectively target cancer cells.

METHODS

We searched various electronic databases including PubMed, Web of Science, and Google Scholar for peer-reviewed english-language articles. Selected articles ranging from research papers, clinical studies, and review articles on the ROS production in living systems, its role in cancer development and cancer treatment, and the role of microbiota in ROS-dependent cancer therapy were analyzed.

RESULTS

This review highlights oxidative stress in tumors, underlying mechanisms of different relationships of ROS and cancer cells, different ROS-mediated therapeutic strategies and the emerging role of microbiota in cancer therapy.

CONCLUSION

Cancer cells exhibit increased ROS stress and disturbed redox homeostasis which lead to ROS adaptations. ROS-dependent anticancer therapies including ROS scavenging anticancer therapy and ROS boosting anticancer therapy have shown promising results in vitro as well as in vivo. In addition, response to cancer therapy is modulated by the human microbiota which plays a critical role in systemic body functions.

Norcantharidin Inhibits SK-N-SH Neuroblastoma Cell Growth by Induction of Autophagy and Apoptosis

Norcantharidin, a low-toxic analog of the active anticancer compound cantharidin in Mylabris, can inhibit proliferation and induce apoptosis of multiple types of cancer cells. However, the anticancer activities of norcantharidin with respect to neuroblastoma, and its underlying mechanisms, have not been investigated. Therefore, our study was designed to determine the efficacy of norcantharidin on SK-N-SH neuroblastoma cell death and to elucidate detailed mechanisms of activity. In the present study, norcantharidin suppressed the proliferation and cloning ability of SK-N-SH cells in a dose-dependent manner, apparently by reducing the mitochondrial membrane potential and arresting SK-N-SH cells at the G2/M stage, accompanied by elevated expressions of p21 and decreased expressions of cyclin B1 and cell division control 2. Treatment by norcantharidin induced significant mitophagy and autophagy, as demonstrated by a decrease in Translocase Of Outer Mitochondrial Membrane 20 (TOM20), increased beclin1 and LC3-II protein expression, reduced protein SQSTM1/p62 expression, and accumulation of punctate LC3 in the cytoplasm of SK-N-SH cells. In addition, norcantharidin induced apoptosis through regulating the expression of B-cell lymphoma 2-associated X protein/B-cell lymphoma 2 and B-cell lymphoma 2-associated X protein/myeloid cell leukemia 1 and activating caspase-3 and caspase-9-dependent endogenous mitochondrial pathways. We also observed an increase in phosphor-AMP-activated protein kinase accompanied with a decrease in phosphor-protein kinase B and mammalian target of rapamycin expression after treatment with norcantharidin. Subsequent studies indicated that norcantharidin participates in cellular autophagy and apoptosis via activation of the c-Jun NH2-terminal kinases/c-Jun pathway. In conclusion, our results demonstrate that norcantharidin can reduce the mitochondrial membrane potential, induce mitophagy, and subsequently arouse cellular autophagy and apoptosis; the AMP-activated protein kinase, protein kinase B/mammalian target of rapamycin, and c-Jun NH2-terminal kinases/c-Jun signaling pathways are widely involved in these processes. Thus, the traditional Chinese medicine norcantharidin could be a novel therapeutic strategy for treating neuroblastoma.

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.

Crude extract of Euphorbia formosana induces apoptosis of DU145 human prostate cancer cells acts through the caspase-dependent and independent signaling pathway

Prostate cancer is the most frequently diagnosed malignancy in men and the second highest contributor of male cancer mortality. The crude extract of Euphorbia formosana (CEEF) has been used for treatment of different diseases but the cytotoxic effects of CEEF on human cancer cells have not been reported. The purpose of the present experiments was to determine effects of CEEF on cell cycle distribution and induction of apoptosis in DU145 human prostate cancer cells in vitro. Contrast-phase microscope was used for examining cell morphological changes. Flow cytometric assays were used for cell viability, cell cycle, apoptosis, reactive oxygen species, and Ca²⁺ production and mitochondria membrane potential (ΔΨ_m ). Western blotting was used for examining protein expression of cell cycle and apoptosis associated proteins. Real-time PCR was used for examining mRNA levels of caspase-3, -8, and -9, AIF, and Endo G. Confocal laser microscope was used to examine the translocation of AIF, Endo G, and cytochrome in DU145 cells after CEEF exposure. CEEF-induced cell morphological changes, decreased the percentage of viable cells, and induced S phase arrest and apoptosis in DU145 cells. Furthermore, CEEF promoted RAS and Ca²⁺ production and reduced ΔΨ_m levels. Real-time QPCR confirmed that CEEF promoted the mRNA expression of caspase-3 and -9, AIF and Endo G and we found that AIF and Endo G and cytochrome c were released from mitochondria. Taken together, CEEF-induced cytotoxic effects via ROS production, induced S phase arrest and induction of apoptosis through caspase-dependent and independent and mitochondria-dependent pathways in DU245 cancer cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1600-1611, 2016.

Amide-linked local anesthetics induce apoptosis in human non-small cell lung cancer

BACKGROUND

A retrospective analysis of patients undergoing cancer surgery suggested that using local anesthetics could reduce cancer recurrence and improve survival rate. Previous studies have indicated that local anesthetics may induce apoptosis in several kinds of cells in vitro, but the mechanism is unclear.

METHODS

Cell viability was analyzed by MTS; reactive oxygen species (ROS), mitochondrial membrane potential (MMP, ∆Ψm), cell cycle distribution, and cell apoptosis assay were detected by flow cytometry; DNA damage was measured by comet assay; cell invasion and migration were observed by microscopy; The expression level of related proteins was detected by western blot assay.

RESULTS

The results indicated that lidocaine and ropivacaine could decrease viability, induce G0/G1 phase arrest and apoptosis in human non-small cell lung cancer (NSCLC) cells A549 and H520. Invasion and migration were suppressed. Western blot indicated the related apoptotic pathways proteins changed accordingly. Additionally, lidocaine and ropivacaine downregulated ∆Ψm, provoked DNA damage, upregulated ROS production and activated mitogen-activated protein kinase (MAPK) pathways in A549 and H520 cells.

CONCLUSIONS

The cytotoxic effect of amide-linked local anesthetics on NSCLC cells were mainly due to apoptosis. The antitumor mechanism of lidocaine and ropivacaine may involve apoptotic pathways and MAPK pathways.

Exposure to High-Dose Diesel Exhaust Particles Induces Intracellular Oxidative Stress and Causes Endothelial Apoptosis in Cultured In Vitro Capillary Tube Cells

Previous studies suggest a direct correlation between exposure to diesel exhaust particles (DEP) and the onset of vascular permeability, presumably through the disruption of the adherens junctions. This would lead to deleterious effects on vasculature, such as acute myocardial infarction and atherosclerosis. Although the mechanism remains unclear, we demonstrate DEP-induced mitochondrial reactive oxygen species generation, which may be a central cause of the above vascular disorders. In vitro capillary-like HUVEC tube cells are used in this study and show that acute DEP exposure stimulates ATP depletion, followed by depolarization of their actin cytoskeleton, which sequentially inhibits PI3K/Akt activity and induces endothelial apoptosis. These events are accompanied by induction of p53/Mdm2 feedback regulation at 10 µg/mL DEP and produce 20 % cell apoptosis. Nevertheless, 100 µg/mL DEP augments tube cell apoptosis up to 70 % but disrupts the p53 negative regulator Mdm2. Addition of N-acetylcysteine provides substantial protection against the cytotoxic effects of DEP. In summary, exposure to a low dose of DEP actin triggers cytoskeleton depolarization, reduces PI3K/Akt activity, and induces a p53/Mdm2 feedback loop, and a high dose causes apoptosis by depleting Mdm2.

The protein PprI provides protection against radiation injury in human and mouse cells

Severe acute radiation injuries are both very lethal and exceptionally difficult to treat. Though the radioresistant bacterium D. radiodurans was first characterized in 1956, genes and proteins key to its radioprotection have not yet to be applied in radiation injury therapy for humans. In this work, we express the D. radiodurans protein PprI in Pichia pastoris yeast cells transfected with the designed vector plasmid pHBM905A-pprI. We then treat human umbilical endothelial vein cells and BALB/c mouse cells with the yeast-derived PprI and elucidate the radioprotective effects the protein provides upon gamma irradiation. We see that PprI significantly increases the survival rate, antioxidant viability, and DNA-repair capacity in irradiated cells and decreases concomitant apoptosis rates and counts of damage-indicative γH2AX foci. Furthermore, we find that PprI reduces mortality and enhances bone marrow cell clone formation and white blood cell and platelet counts in irradiated mice. PprI also seems to alleviate pathological injuries to multiple organs and improve antioxidant viability in some tissues. Our results thus suggest that PprI has crucial radioprotective effects on irradiated human and mouse cells.

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.

Evaluation of DNA damage induced by norcantharidin in human cultured lymphocytes

Norcantharidin (NCTD) is currently used in the treatment of several cancers such as leukemia, melanoma and hepatoma. The mechanism of action of NCTD is suggested to involve induction of apoptosis of cancer cells via production of reactive oxygen species. In this study, the genotoxic effect of different concentrations of NCTD (1, 10 and 20 μm) in human lymphocytes was investigated using sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) assays. The results revealed that NCTD significantly increased the rate of SCEs (p < 0.05) in a dose-dependent manner. In addition, NCTD significantly increased the number of high-frequency cells (SCEs ≥ 8, p < 0.05). However, NCTD did not have any significant effect on the rate of CAs (p > 0.05). In addition, no significant differences were detected in the mitotic index or proliferative index at examined doses (up to 20 μm). In conclusion, NCTD is genotoxic to human cultured lymphocytes as measured by SCE assay.

Targeting Cellular Metabolism Chemosensitizes the Doxorubicin-Resistant Human Breast Adenocarcinoma Cells

Metabolic energy preferentially produced by glycolysis was an advantageous metabolic phenotype of cancer cells. It is also an essential contributor to the progression of multidrug resistance in cancer cells. By developing human breast cancer MCF-7 cells resistant to doxorubicin (DOX) (MCF-7/MDR cells), the effects and mechanisms of 2-deoxy-D-glucose (2DG), a glucose analogue, on reversing multidrug resistance were investigated. 2DG significantly inhibited the viability of MCF-7/MDR cells and enhanced DOX-induced apoptosis by upregulating protein expression of AMPKα, P53, and caspase-3. The study demonstrated that energy restriction induced by 2DG was relevant to the synergistic effect of 2DG and DOX. The proteins of multidrug gene (the MDR-related protein, MRP1) and P-glycoprotein (P-gp) in MCF-7/MDR cells were downregulated after exposure to 2DG, accompanied with the suppression of the activity of ATP-dependent drug-efflux pump and transmembrane transporter, increasing the intracellular accumulation of DOX to reverse the chemoresistance in multidrug cancer cells.

Atg5 siRNA inhibits autophagy and enhances norcantharidin-induced apoptosis in hepatocellular carcinoma

Cantharidin is a terpenoid isolated from Chinese blister beetles, and norcantharidin (NCTD) is a demethylated analog of cantharidin. It has been reported that cantharidin and norcantharidin have anticancer activities. Growing evidence suggests that inhibiting autophagy can induce apoptosis in the human hepatoma cell line HepG2. The objective of the present study was to determine whether inhibition of autophagy enhances NCTD-induced apoptosis in HepG2 cells. HepG2 cells were cultured in DMEM containing NCTD. Autophagy was upregulated in the presence of HBSS media supplemented with Ca2+ and Mg2+ and 10 mM HEPES and downregulated in the presence of 3-methyladenine (3-MA) and Atg5 siRNA. Autophagy, cell viability, and the expression of apoptotic proteins were assessed in HepG2 cells. Our data showed that cell apoptosis generally increased after norcantharidin treatment in HepG2 cells. Expression of LC3-II, an autophagosome marker, increased when cells were treated with HBSS media. It also increased cell viability. However, in the presence of 3-MA and Atg5 siRNA, autophagy was inhibited, LC3-II expression decreased and cell apoptosis increased. There was increased expression of Bax, cytochrome c, cleaved caspase-3, caspase-9 and PARP and the mitochondrial membrane potential was disrupted. Additionally, increased apoptosis was accompanied by increased reactive oxygen species (ROS) production. NCTD has anticancer activity, and Atg5 siRNA-mediated downregulation of autophagy enhanced its anticancer actions due to ROS generation and activation of the mitochondrial apoptosis pathway.

DMH1 (4-[6-(4-isopropoxyphenyl)pyrazolo[1,5-a]pyrimidin-3-yl]quinoline) inhibits chemotherapeutic drug-induced autophagy

Our previous work found that DMH1 (4-[6-(4-isopropoxyphenyl)pyrazolo [1,5-a]pyrimidin-3-yl]quinoline) was a novel autophagy inhibitor. Here, we aimed to investigate the effects of DMH1 on chemotherapeutic drug-induced autophagy as well as the efficacy of chemotherapeutic drugs in different cancer cells. We found that DMH1 inhibited tamoxifen- and cispcis-diaminedichloroplatinum (II) (CDDP)-induced autophagy responses in MCF-7 and HeLa cells, and potentiated the anti-tumor activity of tamoxifen and CDDP for both cells. DMH1 inhibited 5-fluorouracil (5-FU)-induced autophagy responses in MCF-7 and HeLa cells, but did not affect the anti-tumor activity of 5-FU for these two cell lines. DMH1 itself did not induce cell death in MCF-7 and HeLa cells, but inhibited the proliferation of these cells. In conclusion, DMH1 inhibits chemotherapeutic drug-induced autophagy response and the enhancement of efficacy of chemotherapeutic drugs by DMH1 is dependent on the cell sensitivity to drugs.

Norcantharidin inhibits Wnt signal pathway via promoter demethylation of WIF-1 in human non-small cell lung cancer

Wingless-type (Wnt) family of secreted glycoproteins is a group of signal molecules implicated in oncogenesis. Abnormal activation of Wnt signal pathway is associated with a variety of human cancers, including non-small cell lung cancer (NSCLC). Wnt antagonists, such as the secreted frizzled-related protein (SFRP) family, Wnt inhibitory factor-1 (WIF-1) and cerberus, inhibit Wnt signal pathway by directly binding to Wnt molecules. Norcantharidin (NCTD) is known to possess anticancer activity but less nephrotoxicity than cantharidin. In this study, we found that NCTD inhibited cell proliferation, induced apoptosis, arrested cell cycle and suppressed cell invasion/migration in vitro. Additionally, Wnt signal pathway transcription was also suppressed. NCTD treatment blocked cytoplasmic translocation of beta-catenin into the nucleus. Alterations of apoptosis-related proteins, such as Bax, cleaved caspase-3 (pro-apoptotic) and Bcl-2 (anti-apoptotic), had been detected. Furthermore, the expression levels of WIF-1 and SFRP1 were significantly increased in NCTD-treated groups compared with negative control (NC) groups. Abnormal methylation was observed in NC groups, while NCTD treatment promoted WIF-1 demethylation. The present study revealed that NCTD activated WIF-1 via promoter demethylation, inhibiting the canonical Wnt signal pathway in NSCLC, which may present a new therapeutic target in vivo.

Norcantharidin induces growth inhibition and apoptosis of glioma cells by blocking the Raf/MEK/ERK pathway

Background

Malignant gliomas represent the most common primary brain tumors. The prognosis of patients with malignant gliomas is poor in spite of current intensive therapy and novel therapeutic modalities are needed. Here we report that norcantharidin is effective in growth inhibition of glioma cell lines in vitro.

Methods

Glioma cell lines (U87 and C6) were treated with norcantharidin. The effects of norcantharidin on the proliferation and apoptosis of glioma cells were measured by 3-[4,5-dimethylthiazol-2-thiazolyl]-2,5-diphenyl-tetrazolium bromide (MTT) assay and flow cytometry. Western blotting was employed to determine the signaling pathway changes.

Results

The results showed that norcantharidin effectively inhibited cell growth and induced apoptosis in glioma cells, which was concurrent with inhibition of the expression of phospho-MEK and phospho-ERK. Furthermore, the expression anti-apoptotic proteins Bcl-2 and Mcl-1 significantly reduced, but no changes in Bcl-xL and Bax.

Conclusions

Our findings demonstrate that norcantharidin is effective for growth inhibition of glioma cell lines and suggest that norcantharidin may be a new therapeutic option for patients with glioma.