Artesunate induces oxidative DNA damage, sustained DNA double-strand breaks, and the ATM/ATR damage response in cancer cells

Translationally controlled tumor protein is a novel biological target for neurofibromatosis type 1-associated tumors

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease that predisposes individuals to develop benign neurofibromas and malignant peripheral nerve sheath tumors (MPNSTs). Due to the lack of information on the molecular mechanism of NF1-associated tumor pathogenesis or biomarkers/therapeutic targets, an effective treatment for NF1 tumors has not been established. In this study, the novel NF1-associated protein, translationally controlled tumor protein (TCTP), was identified by integrated proteomics and found to be up-regulated via activated MAPK/PI3K-AKT signaling in response to growth factors in NF1-deficient Schwann cells. Immunohistochemical analysis of NF1-associated tumors revealed that the TCTP expression level correlated with tumorigenicity. In NF1-deficient MPNST cells, TCTP protein but not mRNA was down-regulated by NF1 GTPase-activating protein-related domain or MAPK/PI3K inhibitors, and this correlated with suppression of mammalian target of rapamycin (mTOR) signaling. mTOR inhibition by rapamycin also down-regulated TCTP protein expression, whereas knockdown or overexpression of TCTP suppressed or activated mTOR signaling, respectively, and affected cell viability. These results suggest that a positive feedback loop between TCTP and mTOR contributes to NF1-associated tumor formation. Last, the anti-tumor effect of artesunate, which binds to and degrades TCTP, was evaluated. Artesunate significantly suppressed the viability of MPNST cells but not normal Schwann cells, and the TCTP level inversely correlated with artesunate sensitivity. Moreover, combinational use of artesunate and rapamycin enhanced the cytotoxic effect on MPNST cells. These findings suggest that TCTP is functionally implicated in the progression of NF1-associated tumors and could serve as a biological target for their therapy.

Functional interplay between ATM/ATR-mediated DNA damage response and DNA repair pathways in oxidative stress

To maintain genome stability, cells have evolved various DNA repair pathways to deal with oxidative DNA damage. DNA damage response (DDR) pathways, including ATM-Chk2 and ATR-Chk1 checkpoints, are also activated in oxidative stress to coordinate DNA repair, cell cycle progression, transcription, apoptosis, and senescence. Several studies demonstrate that DDR pathways can regulate DNA repair pathways. On the other hand, accumulating evidence suggests that DNA repair pathways may modulate DDR pathway activation as well. In this review, we summarize our current understanding of how various DNA repair and DDR pathways are activated in response to oxidative DNA damage primarily from studies in eukaryotes. In particular, we analyze the functional interplay between DNA repair and DDR pathways in oxidative stress. A better understanding of cellular response to oxidative stress may provide novel avenues of treating human diseases, such as cancer and neurodegenerative disorders.

Synergism of cytotoxicity effects of triptolide and artesunate combination treatment in pancreatic cancer cell lines

BACKGROUND

Triptolide, extracted from the herb Tripteryglum wilfordii Hook.f that has long been used as a natural medicine in China, has attracted much interest for its anti-cancer effects against some kinds of tumours in recent years. Artesunate, extracted from the Chinese herb Artemisia annua, has proven to be effective and safe as an anti-malarial drug that possesses anticancer potential. The present study attempted to clarify if triptolide enhances artesunate-induced cytotoxicity in pancreatic cancer cell lines in vitro and in vivo.

METHODS

In vitro, to test synergic actions, cell viability and apoptosis were analyzed after treatment of pancreatic cancer cell lines with the two agents singly or in combination. The molecular mechanisms of apoptotic effects were also explored using qRT-PCR and Western blotting. In vivo, a tumor xenograft model was established in nude mice, for assessment of inhibitory effects of triptolide and artesunate.

RESULTS

We could show that the combination of triptolide and artesunate could inhibit pancreatic cancer cell line growth, and induce apoptosis, accompanied by expression of HSP 20 and HSP 27, indicating important roles in the synergic effects. Moreover, tumor growth was decreased with triptolide and artesunate synergy.

CONCLUSION

Our result indicated that triptolide and artesunate in combination at low concentrations can exert synergistic anti-tumor effects in pancreatic cancer cells with potential clinical applications.

The eucalyptus oil ingredient 1,8-cineol induces oxidative DNA damage

The natural compound 1,8-cineol, also known as eucalyptol, is a major constituent of eucalyptus oil. This epoxy-monoterpene is used as flavor and fragrance in consumer goods as well as medical therapies. Due to its anti-inflammatory properties, 1,8-cineol is also applied to treat upper and lower airway diseases. Despite its widespread use, only little is known about the genotoxicity of 1,8-cineol in mammalian cells. This study investigates the genotoxicity and cytotoxicity of 1,8-cineol in human and hamster cells. First, we observed a significant and concentration-dependent increase in oxidative DNA damage in human colon cancer cells, as detected by the Formamidopyrimidine-DNA glycosylase (Fpg)-modified alkaline comet assay. Pre-treatment of cells with the antioxidant N-acetylcysteine prevented the formation of Fpg-sensitive sites after 1,8-cineol treatment, supporting the notion that 1,8-cineol induces oxidative DNA damage. In the dose range of DNA damage induction, 1,8-cineol did neither reduce the viability of colon cancer cells nor affected their cell cycle distribution, suggesting that cells tolerate 1,8-cineol-induced oxidative DNA damage by engaging DNA repair. To test this hypothesis, hamster cell lines with defects in BRCA2 and Rad51, which are essentials players of homologous recombination (HR)-mediated repair, were treated with 1,8-cineol. The monoterpene induced oxidative DNA damage and subsequent DNA double-strand breaks in the hamster cell lines tested. Intriguingly, we detected a significant concentration-dependent decrease in viability of the HR-defective cells, whereas the corresponding wild-type cell lines with functional HR were not affected. Based on these findings, we conclude that 1,8-cineol is weakly genotoxic, inducing primarily oxidative DNA damage, which is most likely tolerated in DNA repair proficient cells without resulting in cell cycle arrest and cell death. However, cells with deficiency in HR were compromised after 1,8-cineol treatment, suggesting a protective role of HR in response to high doses of 1,8-cineol.

Dihydroartemisinin is a Hypoxia-Active Anti-Cancer Drug in Colorectal Carcinoma Cells

Tumor hypoxia is one main biological factor that drives resistance to chemotherapy and radiotherapy. To develop a novel strategy for overcoming hypoxia-induced therapy resistance, we examined the anti-neoplastic activity of the reactive oxygen donor dihydroartemisinin (DHA) in human colon cancer cell lines in normoxia and severe hypoxia. In addition, we analyzed the involvement of the intrinsic apoptosis pathway for DHA-mediated cytotoxicity in HCT116 cells in short-term and long-term in vitro assays. When applied at lower concentrations (≤25 μM), DHA induced apoptosis in Colo205, HCT15, and HCT116 cells, whereas necrotic cell death was increased when cells were treated with higher DHA concentrations (50 μM). However, no preference for DHA-induced apoptosis or necrosis could be detected between the treatment under normoxic or hypoxic conditions. Moreover, DHA potently reduced clonogenic survival of HCT116 cells in normoxia and hypoxia. Treatment of HCT116 cells with 25 μM DHA resulted in activation of Bax under normoxic and hypoxic conditions. Interestingly, cytochrome c release from the mitochondria and caspase-activation were observed only under normoxic conditions, whereas, under hypoxic conditions DHA induced a caspase-independent apoptosis-like cell death. However, under both conditions, generation of reactive oxygen species was an important mediator of DHA-induced toxicity. Further molecular analysis suggests that DHA-mediated cell death involves different sets of pro-apoptotic Bcl-2 family members. The pronounced cytotoxic activity of DHA in severe hypoxia as well as normoxia offers new perspectives for targeting the hypoxic tumor cell fraction to improve treatment outcome for cancer patients.

The synergistic anticancer effect of artesunate combined with allicin in osteosarcoma cell line in vitro and in vivo

BACKGROUND

Artesunate, extracted from Artemisia annua, has been proven to have anti-cancer potential. Allicin, diallyl thiosulfinate, the main biologically active compound derived from garlic, is also of interest in cancer treatment research. This object of this report was to document synergistic effects of artesunate combined with allicin on osteosarcoma cell lines in vitro and in vivo.

METHODS

After treatment with artesunate and allicin at various concentrations, the viability of osteosarcoma cells was analyzed by MTT method, with assessment of invasion and motility, colony formation and apoptosis. Western Blotting was performed to determine the expression of caspase-3/9, and activity was also detected after drug treatment. Moreover, in a nude mouse model established with orthotopic xenograft tumors, tumor weight and volume were monitored after drug administration via the intraperitoneal (i.p.) route.

RESULTS

The viability of osteosarcoma cells in the combination group was significantly decreased in a concentration and time dependent manner; moreover, invasion, motility and colony formation ability were significantly suppressed and the apoptotic rate was significantly increased through caspase-3/9 expression and activity enhancement in the combination group. Furthermore, suppression of tumor growth was evident in vivo.

CONCLUSION

Our results indicated that artesunate and allicin in combination exert synergistic effects on osteosarcoma cell proliferation and apoptosis.

Treatment of Iron-Loaded Veterinary Sarcoma by Artemisia annua

Artemisinin, a constituent of Artemisia annua L., is a well-known antimalarial drug. Artemisinin-type drugs also inhibit cancer growth in vitro and in vivo. Herbal extracts of A. annua inhibit the growth of cancer cell lines. Here, we report on the use of capsules containing powder of Herba Artemisiae annuae to treat pet sarcoma. The surgical tumor removal as standard treatment was supplemented by adjuvant therapy with A. annua. One cat and one dog with fibrosarcoma survived 40 and 37 months, respectively, without tumor relapse. Two other dogs suffering from fibrosarcoma and hemangioendothelial sarcoma also showed complete remission and are still alive after 39 and 26 months, respectively. A. annua was well tolerated without noticeable side effects. These four cases indicate that A. annua may be a promising herbal drug for cancer therapy.

Artemisinin derivative artesunate induces radiosensitivity in cervical cancer cells in vitro and in vivo

Objective

Cervical cancer is the third most common type of cancer in women worldwide and radiotherapy remains its predominant therapeutic treatment. Artesunate (ART), a derivative of artemisinin, has shown radiosensitization effect in previous studies. However, such effects of ART have not yet been revealed for cervical cancer cells.

Methods

The effect of ART on radiosensitivity of human cervical cancer cell lines HeLa and SiHa was assessed using the clonogenic assay. Cell cycle progression and apoptosis alterations were analyzed by flow cytometry. For in vivo study, HeLa or SiHa cells were inoculated into nude mice to establish tumors. Tissues from xenografts were obtained to detect the changes of microvessel density, apoptosis and cell cycle distribution. Microarray was used to analyze differentially expressed genes.

Results

ART increased the radiosensitivity of HeLa cells (SER = 1.43, P < 0.001) but not of SiHa cells. Apoptosis and the G2-M phase transition induced by X-ray irradiation (IR) were enhanced by ART via increased Cyclin B1 expression in HeLa cells. Tumor growth of xenografts from HeLa but not SiHa cells was significantly inhibited by irradiation combined with ART (tumor volume reduction of 72.34% in IR + ART group vs. 41.22% in IR group in HeLa cells and 48.79% in IR + ART group vs. 44.03% in IR alone group in SiHa cells). Compared with the irradiated group, cell apoptosis was increased and the G2/M cell cycle arrest was enhanced in the group receiving irradiation combined with ART. Furthermore, compared with radiation alone, X-ray irradiation plus ART affected the expression of 203 genes that function in multiple pathways including RNA transport, the spliceosome, RNA degradation and p53 signaling.

Conclusion

ART potently abrogates the G2 checkpoint control in HeLa cells. ART can induce radiosensitivity of HeLa cells in vitro and in vivo.

A conceptually new treatment approach for relapsed glioblastoma: coordinated undermining of survival paths with nine repurposed drugs (CUSP9) by the International Initiative for Accelerated Improvement of Glioblastoma Care

To improve prognosis in recurrent glioblastoma we developed a treatment protocol based on a combination of drugs not traditionally thought of as cytotoxic chemotherapy agents but that have a robust history of being well-tolerated and are already marketed and used for other non-cancer indications. Focus was on adding drugs which met these criteria: a) were pharmacologically well characterized, b) had low likelihood of adding to patient side effect burden, c) had evidence for interfering with a recognized, well-characterized growth promoting element of glioblastoma, and d) were coordinated, as an ensemble had reasonable likelihood of concerted activity against key biological features of glioblastoma growth. We found nine drugs meeting these criteria and propose adding them to continuous low dose temozolomide, a currently accepted treatment for relapsed glioblastoma, in patients with recurrent disease after primary treatment with the Stupp Protocol. The nine adjuvant drug regimen, Coordinated Undermining of Survival Paths, CUSP9, then are aprepitant, artesunate, auranofin, captopril, copper gluconate, disulfiram, ketoconazole, nelfinavir, sertraline, to be added to continuous low dose temozolomide. We discuss each drug in turn and the specific rationale for use- how each drug is expected to retard glioblastoma growth and undermine glioblastoma's compensatory mechanisms engaged during temozolomide treatment. The risks of pharmacological interactions and why we believe this drug mix will increase both quality of life and overall survival are reviewed.

Synergistic inhibition of angiogenesis by artesunate and captopril in vitro and in vivo

Inhibition of angiogenesis represents one major strategy of cancer chemotherapy. In the present investigation, we investigated the synergism of artesunate and captopril to inhibit angiogenesis. Artesunate is an antimalarial derivative of artemisinin from the Chinese medicinal plant, Artemisia annua L., which also reveals profound anticancer activity in vitro and in vivo. Captopril is an angiotensin I-converting (ACE) inhibitor, which is well established in Western academic medicine. Both compounds inhibited migration of human umbilical vein endothelial cells (HUVECs) in vitro. The combination of both drugs resulted in synergistically inhibited migration. Whereas artesunate inhibited HUVEC growth in the XTT assay, captopril did not, indicating independent modes of action. We established a chorioallantoic membrane (CAM) assay of quail embryos (Coturnix coturnix L.) and a computer-based evaluation routine for quantitative studies on vascularization processes in vivo. Artesunate and captopril inhibited blood vessel formation and growth. For the first time, we demonstrated that both drugs revealed synergistic effects when combined. These results may also have clinical impact, since cardiovascular diseases and cancer frequently occur together in older cancer patients. Therefore, comorbid patients may take advantage, if they take captopril to treat cardiovascular symptoms and artesunate to treat cancer.

Differential interactions of the broad spectrum drugs artemisinin, dihydroartemisinin and artesunate with serum albumin

Artemisinin is a drug, widely used in malaria treatment. As the binding affinity of artemisinin and its derivatives dihydroartemisinin and artesunate to blood serum proteins might influence the effectiveness of the drug, binding of artemisinin and derivatives to serum albumin was studied under near physiological conditions. Binding kinetics indicate a simple, single-step association process for all artemisinin derivatives. The determined changes in enthalpy and entropy upon drug binding clearly indicate that hydrophobic forces are most important for artemisinin and dihydroartemisinin binding, whereas binding of artesunate is governed by both hydrophilic and hydrophobic forces. Key residues, which are most likely involved in binding of the respective compounds, were identified in subsequent protein/drug docking studies. The obtained results not only explain differences in between artemisinin and derivatives but generally illustrate how slight modifications in a drug can significantly affect principles underlying drug binding to target proteins.

Subamolide a induces mitotic catastrophe accompanied by apoptosis in human lung cancer cells

This study investigated the anticancer effects of subamolide A (Sub-A), isolated from Cinnamomum subavenium, on human nonsmall cell lung cancer cell lines A549 and NCI-H460. Treatment of cancer cells with Sub-A resulted in decreased cell viability of both lung cancer cell lines. Sub-A induced lung cancer cell death by triggering mitotic catastrophe with apoptosis. It triggered oxidant stress, indicated by increased cellular reactive oxygen species (ROS) production and decreased glutathione level. The elevated ROS triggered the activation of ataxia-telangiectasia mutation (ATM), which further enhanced the ATF3 upregulation and subsequently enhanced p53 function by phosphorylation at Serine 15 and Serine 392. The antioxidant, EUK8, significantly decreased mitotic catastrophe by inhibiting ATM activation, ATF3 expression, and p53 phosphorylation. The reduction of ATM and ATF3 expression by shRNA decreased Sub-A-mediated p53 phosphorylation and mitotic catastrophe. Sub-A also caused a dramatic 70% reduction in tumor size in an animal model. Taken together, cell death of lung cancer cells in response to Sub-A is dependent on ROS generation, which triggers mitotic catastrophe followed by apoptosis. Therefore, Sub-A may be a novel anticancer agent for the treatment of nonsmall cell lung cancer.

Treatment outcome of intravenous artesunate in patients with severe malaria in the Netherlands and Belgium

Background

Intravenous (IV) artesunate is the treatment of choice for severe malaria. In Europe, however, no GMP-manufactured product is available and treatment data in European travellers are scarce. Fortunately, artesunate became available in the Netherlands and Belgium through a named patient programme. This is the largest case series of artesunate treated patients with severe malaria in Europe.

Methods

Hospitalized patients treated with IV artesunate between November 2007 and December 2010 in the Netherlands and Belgium were retrospectively evaluated. Patient characteristics, treatment and clinical outcome were recorded on a standardized form and mortality, parasite clearance times and the occurrence of adverse events were evaluated.

Results

Of the 68 treated patients, including 55 with severe malaria, two patients died (2/55 = 3.6%). The mean time to 50% parasite clearance (PCT50), 90% and 99% were 4.4 hours (3.9 - 5.2), 14.8 hours (13.0 - 17.2), and 29.5 hours (25.9 - 34.4) respectively. Artesunate was well tolerated. However, an unusual form of haemolytic anaemia was observed in seven patients. The relationship with artesunate remains uncertain.

Conclusions

Data from the named patient programme demonstrate that IV artesunate is effective and well-tolerated in European travellers lacking immunity. However, increased attention needs to be paid to the possible development of haemolytic anaemia 2-3 weeks after start of treatment.

Treatment of IV artesunate should be limited to the period that IV treatment is required and should be followed by a full oral course of an appropriate anti-malarial drug.