Copper chelation selectively kills colon cancer cells through redox cycling and generation of reactive oxygen species

Background: Metals including iron, copper and zinc are essential for physiological processes yet can be toxic at high concentrations. However the role of these metals in the progression of cancer is not well defined. Here we study the anti-tumor activity of the metal chelator, TPEN, and define its mechanism of action.Methods: Multiple approaches were employed, including cell viability, cell cycle analysis, multiple measurements of apoptosis, and mitochondrial function. In addition we measured cellular metal contents and employed EPR to record redox cycling of TPEN-metal complexes. Mouse xenografts were also performed to test the efficacy of TPEN in vivo.Results: We show that metal chelation using TPEN (5μM) selectively induces cell death in HCT116 colon cancer cells without affecting the viability of non-cancerous colon or intestinal cells. Cell death was associated with increased levels of reactive oxygen species (ROS) and was inhibited by antioxidants and by prior chelation of copper. Interestingly, HCT116 cells accumulate copper to 7-folds higher levels than normal colon cells, and the TPEN-copper complex engages in redox cycling to generate hydroxyl radicals. Consistently, TPEN exhibits robust anti-tumor activity in vivo in colon cancer mouse xenografts.Conclusion: Our data show that TPEN induces cell death by chelating copper to produce TPEN-copper complexes that engage in redox cycling to selectively eliminate colon cancer cells. © 2014 Fatfat et al.; licensee BioMed Central Ltd

Thymoquinone inhibits tumor growth and induces apoptosis in a breast cancer xenograft mouse model: The role of p38 MAPK and ROS

Due to narrow therapeutic window of cancer therapeutic agents and the development of resistance against these agents, there is a need to discover novel agents to treat breast cancer. The antitumor activities of thymoquinone (TQ), a compound isolated from Nigella sativa oil, were investigated in breast carcinoma in vitro and in vivo. Cell responses after TQ treatment were assessed by using different assays including MTT assay, annexin V-propidium iodide staining, Mitosox staining and Western blot. The antitumor effect was studied by breast tumor xenograft mouse model, and the tumor tissues were examined by histology and immunohistochemistry. The level of antioxidant enzymes/molecules in mouse liver tissues was measured by commercial kits. Here, we show that TQ induced p38 phosphorylation and ROS production in breast cancer cells. These inductions were found to be responsible for TQ’s anti-proliferative and pro-apoptotic effects. Moreover, TQ-induced ROS production regulated p38 phosphorylation but not vice versa. TQ treatment was found to suppress the tumor growth and this effect was further enhanced by combination with doxorubicin. TQ also inhibited the protein expression of anti-apoptotic genes, such as XIAP, survivin, Bcl-xL and Bcl-2, in breast cancer cells and breast tumor xenograft. Reduced Ki67 and increased TUNEL staining were observed in TQ-treated tumors. TQ was also found to increase the level of catalase, superoxide dismutase and glutathione in mouse liver tissues. Overall, our results demonstrated that the antiproliferative and pro-apoptotic effects of TQ in breast cancer are mediated through p38 phosphorylation via ROS generation

Thymoquinone Induces Telomere Shortening, DNA Damage and Apoptosis in Human Glioblastoma Cells

Background: A major concern of cancer chemotherapy is the side effects caused by the non-specific targeting of both normal and cancerous cells by therapeutic drugs. Much emphasis has been placed on discovering new compounds that target tumour cells more efficiently and selectively with minimal toxic effects on normal cells. Methodology/Principal Findings: The cytotoxic effect of thymoquinone, a component derived from the plant Nigella sativa, was tested on human glioblastoma and normal cells. Our findings demonstrated that glioblastoma cells were more sensitive to thymoquinone-induced antiproliferative effects. Thymoquinone induced DNA damage, cell cycle arrest and apoptosis in the glioblastoma cells. It was also observed that thymoquinone facilitated telomere attrition by inhibiting the activity of telomerase. In addition to these, we investigated the role of DNA-PKcs on thymoquinone mediated changes in telomere length. Telomeres in glioblastoma cells with DNA-PKcs were more sensitive to thymoquinone mediated effects as compared to those cells deficient in DNA-PKcs. Conclusions/Significance: Our results indicate that thymoquinone induces DNA damage, telomere attrition by inhibiting telomerase and cell death in glioblastoma cells. Telomere shortening was found to be dependent on the status of DNA-PKcs. Collectively, these data suggest that thymoquinone could be useful as a potential chemotherapeutic agent in th

MR imaging of therapy-induced changes of bone marrow

MR imaging of bone marrow infiltration by hematologic malignancies provides non-invasive assays of bone marrow cellularity and vascularity to supplement the information provided by bone marrow biopsies. This article will review the MR imaging findings of bone marrow infiltration by hematologic malignancies with special focus on treatment effects. MR imaging findings of the bone marrow after radiation therapy and chemotherapy will be described. In addition, changes in bone marrow microcirculation and metabolism after anti-angiogenesis treatment will be reviewed. Finally, new specific imaging techniques for the depiction of regulatory events that control blood vessel growth and cell proliferation will be discussed. Future developments are directed to yield comprehensive information about bone marrow structure, function and microenvironment

ANTI-CANCER AND OXIDANT PROPERTIES OF DIFFERENT SESQUITERPENE LACTONES ISOLATED FROM INDIGENOUS LEBANESE PLANTS

Most cancers are of epithelial origin of which skin cancer is the most frequent. Numerous naturally occurring compounds have been identified as skin chemopreventive agents, and many of the best-selling anticancer drugs are plant-derived. While screening for anti-cancer activities of forty-four Middle Eastern plant extracts used in folk medicine, we identified the Lebanese indigenous plants, Centaurea ainetensis and Achillea falcata, to possess potent and selective activities against cancer cells. Bioassay-guided fractionation of these plants’ crude extracts led to the isolation of the sesquiterpene lactone family of plant secondary metabolites having the most potent anti-tumor activities. These included two guaianolides from C. ainetensis: Salograviolide A (Sal-A) and its hydroxy-isomer and four seco-guanolide derivatives from A. falcata: Tanaphillin, 3-beta-methoxy-3-deshydroxy-iso-seco-tanapartholide (beta-Tan), iso-seco-tanapartholide, and 8-hydroxy-3-methoxy-iso-seco-tanaparatholide. We determined the growth inhibitory effects of the isolated sesquiterpene lactones on the human epidermal HaCaT cells, a well characterized model for early stage skin carcinogenesis, and correlated these activities with oxidant potential. We found that Sal-A and beta-Tan exhibited the most potent growth inhibitory effects at concentrations that were not cytotoxic to primary human keratinocytes. Sal-A caused pre-G0/G1 cell cycle arrest and reduced cyclin D1 proteins while beta-Tan induced G2/M arrest and decreased cyclin B1 proteins. Sal-A- and beta-Tan-induced growth inhibition was preceded by an early and progressive accumulation of reactive oxygen species (ROS). Pre-treatment with different anti-oxidants reduced drug-induced ROS generation and abrogated growth inhibition. These studies provide a rationale for designing plant-derived anti-cancer drugs from sesquiterpene lactones

Thymoquinone induces apoptosis in human glioblastoma cell lines

Nigella sativa L. seeds have been traditionally employed for thousands of years as a spice and food preservative, as well as a protective and curative remedy for the treatment of inflammations, liver disorders, and arthritis in Middle Eastern. The main constituent of volatile oil is the thymoquinone (TQ). TQ is the bioactive component that possesses antioxidant, anti-inflammatory, anti-neoplastic, and hepato-protective properties. Previous studies demonstrated anti-cancer properties of TQ in several in vitro and in vivo tumor models. However, therapeutic efficacy of TQ has not been evaluated in glioblastoma. We investigated the effects of TQ against two human glioblastoma cell lines, U87 MG (p53 wild type) and T98G (p53 mutant). TQ decreases cell survival in a dose and time-dependent manner, and more significantly in U87 MG cells than in T98G cells. The cells exposed to 25, 50, and 100 µM TQ for 24 h showed morphological and biochemical features of apoptosis. Morphological changes, nuclear condensation, DNA fragmentation, caspases-9 and -3 activities, and reactive oxygen species (ROS) production were determined. Cell death was found to be apoptotic involving intrinsic pathways as evidenced by increase of caspase-9 activity. ROS were elevated following TQ treatment and antioxidant N-acetyl-cysteine prevented cell death in both cell lines. These findings suggest that TQ induces apoptosis via a mechanism involving ROS and oxidative stress pathway