title: Inhibition of breast cancer cell growth and induction of cell death by 1,1-bis(3'-indolyl)methane (DIM) and 5,5'-dibromoDIM.
abstract: 1,1-Bis(3'-indolyl)methane (DIM) and the 5,5'-dibromo ring substituted DIM (5,5'-diBrDIM) inhibited growth of MCF-7 and MDA-MB-231 breast cancer cells, and IC50 values were 10-20 and 1-5 microM, respectively, in both cell lines. DIM and 5,5'-diBrDIM did not induce p21 or p27 protein levels or alter expression of Sp1 or Sp3 proteins in either cell line. In contrast, 10 microM 5,5'-diBrDIM downregulated cyclin D1 protein in MCF-7 and MDA-MB-231 cells 12 and 24 h after treatment. DIM (20 microM) also decreased cyclin D1 in MCF-7 (24 h) and MDA-MB-231 (12 h), and the DIM/5,5'-diBrDIM-induced degradation of cyclin D1 was blocked by the proteasome inhibitor MG132. Both DIM and 5,5'-diBrDIM induced apoptosis in MCF-7 cells and this was accompanied by decreased Bcl-2, release of mitochondrial cytochrome c, and decreased mitochondrial membrane potential as determined by the red/green fluorescence of JC-1. DIM and 5,5'-diBrDIM induced extensive necrosis in MDA-MB-231 cells; however, this was accompanied by decreased mitochondrial membrane potential primarily in cells treated with 5,5'-diBrDIM but not DIM. Thus, DIM and 5,5'-diBrDIM induce cell death in MCF-7 and MDA-MB-231 cells by overlapping and different pathways, and the ring-substituted DIM represents a novel class of uncharged mitochondrial poisons that inhibit breast cancer cell and tumor growth.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, 4466 TAMU, College Station, TX 77843-4466, USA.
authors.forename: Kathy
authors.initials: K
authors.lastname: Vanderlaag
authors.forename: Ismael
authors.initials: I
authors.lastname: Samudio
authors.forename: Robert
authors.initials: R
authors.lastname: Burghardt
authors.forename: Rola
authors.initials: R
authors.lastname: Barhoumi
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D019938:Cyclin D1 / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D005260:Female; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D007976:Leupeptins / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009336:Necrosis; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013997:Time Factors
chemical_list: C512018:1,1-bis(3'-indolyl)methane; C512019:5,5'-dibromo-1,1-bis(3'-indolyl)methane; D000970:Antineoplastic Agents; D015853:Cysteine Proteinase Inhibitors; D007211:Indoles; D007976:Leupeptins; D061988:Proteasome Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D019938:Cyclin D1; D045304:Cytochromes c; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde