Cu(II)-coumestrol interaction leads to ROS-mediated DNA damage and cell death: a putative mechanism for anticancer activity.
Phytoestrogens have attracted considerable interest as natural alternatives to hormone replacement therapy and their potential as cancer therapeutic agents. Among phytoestrogens, coumestrol has shown multipharmacological properties such as antiinflammatory, neuroprotective, osteoblastic differentiation and anticancer. Though several studies have described anticancer effects of coumestrol, a clear underlying molecular mechanism has not been elucidated. Unlike normal cells, cancer cells contain elevated copper levels that play an integral role in angiogenesis. Copper is an important metal ion associated with the chromatin DNA, particularly with guanine. Thus, targeting copper in cancer cells can serve as effective anticancer strategy. Using human peripheral lymphocytes, we assessed lipid peroxidation, protein carbonylation, reactive oxygen species (ROS) generation, DNA damage and apoptosis by coumestrol in the presence of exogenously added Cu(II) in cells to simulate malignancy-like condition. Results showed that Cu(II)-coumestrol interaction leads to lipid peroxidation and protein carbonylation (markers of oxidative stress), DNA fragmentation and apoptosis in treated lymphocytes. Further, incubation of lymphocytes with ROS scavengers and membrane-permeant copper chelator, neocuproine, resulted in inhibition of DNA damage and apoptosis. This suggests that coumestrol engages in redox cycling of Cu(II) to generate ROS that leads to DNA fragmentation and apoptosis. In conclusion, this is the first report showing that coumestrol targets cellular copper to induce prooxidant death in malignant cells. We believe that such a prooxidant cytotoxic mechanism better explains the anticancer activity of coumestrol. These findings will provide significant insights into the development of new chemical molecules with better copper-chelating and prooxidant properties against cancer cells.
Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India.
Atif
A
Zafar
National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India.
Swarnendra
S
Singh
Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India. Electronic address: imrananaseem2009@gmail.com.
Imrana
I
Naseem
D016588:Anticarcinogenic Agents / Q000737:chemistry / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D020552:Comet Assay; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D003375:Coumestrol / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053938:DNA Fragmentation / Q000187:drug effects; D019587:Dietary Supplements; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D018384:Oxidative Stress / Q000187:drug effects; D048789:Phytoestrogens / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050050:Protein Carbonylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000819:agonists / Q000378:metabolism
D016588:Anticarcinogenic Agents; D015415:Biomarkers; D002614:Chelating Agents; D016166:Free Radical Scavengers; D048789:Phytoestrogens; D017382:Reactive Oxygen Species; D003300:Copper; D003375:Coumestrol
DNA fragmentation; anticancer; apoptosis; copper; coumestrol; redox cycling