Cholesterol as Carcinogen: I. Sarcoma Induction by Cholesterol in a Sensitive Strain of Mice II. Croton Oil a Complete Carcinogen

EARLIER papers in this series (see e.g. Hieger, 1959) have presented experimental results showing that: (a) the carcinogenic factor in the unsaponifiable fraction of human tissue (liver, lung, kidney, muscle) is cholesterol; (b) commercial cholesterol injected subcutaneously induces sarcoma in mice and stringent purification of such cholesterol does not impair its potency; (c) different strains of mice and even different batches of the same pure strain show gross differences of susceptibility to carcinogenesis by cholesterol; (d) the solvents used for administering the cholesterol (e.g. olive oil) have a very low sarcoma-inducing potency (5 tumours in 1122 mice). The first part of this paper deals with an explanation of (c), i.e. the differences in susceptibility to cholesterol. The table shown below (Table I) summarises the results of experiments carried out on cholesterol as carcinogen subsequent to those described in the 1959 paper. Where the "Code " (laboratory labelling) of an experiment carries an asterisk ( *), the mice were housed in a room where hydrocarbon-carcinogens (e.g. benzopyrene) are used (in order to test the effects of contamination). All other experiments were carried out in a room free from hydrocarbon-carcinogens. It is obvious from the results that atmospheric contamination by powerful carcinogens does not carry any risk to experiments where cholesterol is being tested. The experiments are entered in the table in the order in which they were carried out, that is to say, Experiment 1 was started then 2, then 3, etc. This arrangement is useful in demonstrating that no appreciable part of the carcinogenic potency of the active preparations can be attributed to possible variations in the composition of successive batches of the vehicle (olive oil) which is a commercial product, and therefore different samples (hospital dispensary quality) might well have differences in composition owing to seasonal variations or to geographical changes in the source of the olive crop. For example, Experiment 27 gave a high yield of tumours but Experiment 28 a very low yield; since theseCHOLESTEROL AS CARCINOGE

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