Investigation of the key chemical structures involved in the anticancer activity of disulfiram in A549 non-small cell lung cancer cell line

© 2018 The Author(s). Background: Disulfiram (DS), an antialcoholism medicine, demonstrated strong anticancer activity in the laboratory but did not show promising results in clinical trials. The anticancer activity of DS is copper dependent. The reaction of DS and copper generates reactive oxygen species (ROS). After oral administration in the clinic, DS is enriched and quickly metabolised in the liver. The associated change of chemical structure may make the metabolites of DS lose its copper-chelating ability and disable their anticancer activity. The anticancer chemical structure of DS is still largely unknown. Elucidation of the relationship between the key chemical structure of DS and its anticancer activity will enable us to modify DS and speed its translation into cancer therapeutics. Methods: The cytotoxicity, extracellular ROS activity, apoptotic effect of DS, DDC and their analogues on cancer cells and cancer stem cells were examined in vitro by MTT assay, western blot, extracellular ROS assay and sphere-reforming assay. Results: Intact thiol groups are essential for the in vitro cytotoxicity of DS. S-methylated diethyldithiocarbamate (S-Me-DDC), one of the major metabolites of DS in liver, completely lost its in vitro anticancer activity. In vitro cytotoxicity of DS was also abolished when its thiuram structure was destroyed. In contrast, modification of the ethyl groups in DS had no significant influence on its anticancer activity. Conclusions: The thiol groups and thiuram structure are indispensable for the anticancer activity of DS. The liver enrichment and metabolism may be the major obstruction for application of DS in cancer treatment. A delivery system to protect the thiol groups and development of novel soluble copper-DDC compound may pave the path for translation of DS into cancer therapeutics.This work was supported by grant from British Lung Foundation (RG14–8) and Innovate UK (104022).Published versio

Disulfiram modulated ROS–MAPK and NFκB pathways and targeted breast cancer cells with cancer stem cell-like properties

BACKGROUND: Previous studies indicate that disulfiram (DS), an anti-alcoholism drug, is cytotoxic to cancer cell lines and reverses anticancer drug resistance. Cancer stem cells (CSCs) are the major cause of chemoresistance leading to the failure of cancer chemotherapy. This study intended to examine the effect of DS on breast cancer stem cells (BCSCs). METHODS: The effect of DS on BC cell lines and BCSCs was determined by MTT, western blot, CSCs culture and CSCs marker analysis. RESULTS: Disulfiram was highly toxic to BC cell lines in vitro in a copper (Cu)-dependent manner. In Cu-containing medium (1 mu M), the IC50 concentrations of DS in BC cell lines were 200-500 nM. Disulfiram/copper significantly enhanced (3.7-15.5-fold) cytotoxicity of paclitaxel (PAC). Combination index isobologram analysis demonstrated a synergistic effect between DS/Cu and PAC. The increased Bax and Bcl2 protein expression ratio indicated that intrinsic apoptotic pathway may be involved in DS/Cu-induced apoptosis. Clonogenic assay showed DS/Cu-inhibited clonogenicity of BC cells. Mammosphere formation and the ALDH1(+VE) and CD24(Low)/CD44(High) CSCs population in mammospheres were significantly inhibited by exposure to DS/Cu for 24 h. Disulfiram/copper induced reactive oxygen species (ROS) generation and activated its downstream apoptosis-related cJun N-terminal kinase and p38 MAPK pathways. Meanwhile, the constitutive NF kappa B activity in BC cell lines was inhibited by DS/Cu. CONCLUSION: Disulfiram/copper inhibited BCSCs and enhanced cytotoxicity of PAC in BC cell lines. This may be caused by simultaneous induction of ROS and inhibition of NF kappa B. British Journal of Cancer (2011) 104, 1564-1574. doi: 10.1038/bjc.2011.126 www.bjcancer.com Published online 12 April 2011 (C) 2011 Cancer Research U

Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield

Acutodesmus obliquus (SAG 276-1), a microalga with a resistant cell wall, was chosen as a benchmark strain for testing the effect of storage and pretreatment methods on methane yields during anaerobic digestion. A. obliquus was cultivated in sleevebag photobioreactors (batch cultivation). Biomass was centrifuged to a final total solid concentration of 91gL-1 and subjected to different treatments. The biomass was then subjected to biochemical methane potential tests. Among the different storage methods tested, freezing and freeze-drying resulted in significantly higher CH4 yields, i.e., 350 Nm3t-1 VSharvest (=normalized gas volume in m3 corrected to norm temperature and pressure per unit harvested volatile solids) (+53% CH4) and 291Nm3t-1 VSharvest (+29% CH4) compared to the fresh biomass (229 Nm3t-1 VSharvest). For pretreatments, the combined milling and enzyme approach (300 Nm3t-1 VSharvest, +57% CH4), ultrasonication (292 Nm3t-1 VSharvest, +52% CH4) and milling (289 Nm3t-1 VSharvest, +51% CH4) resulted in significantly higher CH4 conversion compared to the untreated control (191Nm3t-1 VSharvest). We found a significantly strong positive correlation between viable cell counts and CH4 yields, and a correlation with the solubilized chemical oxygen demand. Our study revealed that mechanical pretreatments were effective and resulted in highest CH4 yields. In addition, the effect of different storage methods must not be neglected.Austrian COMET program under grant number 834018. Republic of Austria and the Federal Provinces of Styria, Lower Austria and Burgenland. Co-funding from the industry partner Erber Group shall be highly acknowledged.Scopu

Associated effects of storage and mechanical pre-treatments of microalgae biomass on biomethane yields in anaerobic digestion

The pre-treatment of microalgae cell walls is known to be a key factor to enhance methane (CH4) yields during anaerobic digestion. This study investigated the combined effects of two different biomass storage methods and physical pre-treatments on the anaerobic digestion for three different microalgae species. Acutodesmus obliquus, Chlorella vulgaris and Chlorella emersonii were cultivated in 80 L sleevebag photobioreactors (batch mode), and then subjected to different storage (cooling and freezing) and pre-treatment methods prior to anaerobic digestion using the biochemical methane potential (BMP) test. A. obliquus was selected to evaluate pre-treatment methods for further experimentation. Significantly higher CH4 yields of cooled (4 °C) A. obliquus biomass were achieved through ultrasonication (+53% CH4) and wet-milling (+51% CH4). These methods were then applied in follow-up experiments to cooled (4 °C) biomass of C. emersonii and A. obliquus. Ultrasonication again led to significantly higher CH4 yields for A. obliquus biomass (323 dm3 kg−1 CH4 yield calculated at standard gas conditions of 273 K, and 101.5 kPa per unit volatile solids, +41% CH4), and C. emersonii biomass (308 dm3 kg−1; +35% CH4). In a third experiment series, frozen A. obliquus and C. vulgaris biomass were thawed prior to pre-treatment and BMP-testing. Among all BMP tests, the highest CH4 yields were achieved with untreated, freeze-thawed C. vulgaris biomass (406 dm3 kg−1); pre-treatment did not enhance CH4 yields for C. vulgaris, but for A. obliquus (ultrasonication +20%). Pre-treatment was more effective for cooled than freeze-thawed microalgal biomass and combined effects acted strain dependently.This work was performed in the frame of the Austrian COMET program under grant number 834018. It has received funding from the Republic of Austria and the Federal Provinces of Styria, Lower Austria and Burgenland. Co-funding from the industry partner Erber Group shall be highly acknowledged