Indole-3-carbinol-induced death in cancer cells involves EGFR downregulation and is exacerbated in a 3D environment.
Indole-3-carbinol (I3C) is a promising anticancer dietary compound, which inhibits breast cancer in animal models. The objective of the current study was to characterize I3C-induced cell death in a panel of human breast tumorigenic cells (MCF7, MDA-MB-468, MDA-MB-231 and HBL100) in comparison with normal fibroblasts. Since epithelial cells are protected from cell death by a three-dimensional environment, 3D cell culture (collagen I gel and spheroids) was employed to investigate susceptibility to I3C. Cell viability in the presence of 256 microM I3C, a concentration close to the physiologically achievable range, was in the order fibroblasts = HBL100>MDA-MB-231>MCF7>MDA-MB-468 in monolayer culture. However, 3D culture conditions increased the susceptibility of MCF7 and MDA-MB-468 cancer cells towards I3C. I3C induced cell death in breast cancer MCF7, MDA-MB-468 and MDA-MB-231 cells via the mitochondrial apoptotic pathway. I3C significantly reduced levels of epidermal growth factor receptor (EGFR) in MDA-MB-468 after 6 h and in MDA-MB-231 and HBL100 cells after 30 h. Downregulation of EGFR in MDA-MB468 and MDA-MB-231 cells using an EGFR inhibitor resulted in apoptosis. EGFR modulation using EGF or an EGFR inhibitor markedly influenced viability and response to I3C in MDA-MB-468 cells in 3D conditions. EGFR expression was modulated by 3D conditions. Therefore, I3C-induced EGFR reduction in these cells is likely to be responsible for I3C-induced apoptosis.
Cancer Biomarkers and Prevention Group, Department of Biochemistry, University of Leicester, Leicester, LE1 7RH, UK. em9@le.ac.uk
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Moiseeva
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Fox
L M
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Howells
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Temple
M M
MM
Manson
D000255:Adenosine Triphosphate / Q000032:analysis; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3; D053179:Caspase 7; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology; D013997:Time Factors
D061945:Caspase Inhibitors; D004965:Estrogen Antagonists; D007211:Indoles; D011799:Quinazolines; D000255:Adenosine Triphosphate; C016517:indole-3-carbinol; D066246:ErbB Receptors; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases; C088860:4-((3-bromophenyl)amino)-6,7-dimethoxyquinazoline