Indole-3-carbinol-induced modulation of NF-kappaB signalling is breast cancer cell-specific and does not correlate with cell death.
Indole-3-carbinol (I3C), a dietary chemopreventive compound, induces cell death in human breast cancer cells by modulating activities of Src and epidermal growth factor receptor (EGFR). The effect of I3C on NF-kappaB, constitutively activated in breast cancer cells, was investigated. Nuclear extracts of MDA-MB-468, MDA-MB-231 and HBL100 cells contained all of the Rel proteins with similar expression patterns in the latter two. The level of NF-kappaB-regulated reporter gene expression was in the order HBL100 << MDA-MB-468 << MDA-MB-231. Upstream inhibition, using PI3K, EGFR or IKKbeta inhibitors, resulted in cell-specific effects on expression of the NF-kappaB-regulated reporter gene and endogenous genes Bcl-xL, IkappaBalpha and IL-6, as well as on cell viability. The expression patterns of Rel and several NF-kappaB-regulated genes and the response to LY249002 in MDA-MB-468 cells contrasted with those in other cells. I3C induced NF-kappaB-regulated reporter gene expression at 12 h in MDA-MB-468 cells. Conversely, it was reduced at 24 h in HBL100 cells. I3C treatment for 6 h alone or in combination with TNFalpha induced NF-kappaB-regulated reporter gene expression, detected 5 h later, in MDA-MB-468, but not HBL100 cells. I3C induced NF-kappaB p65/p50 DNA binding at 6.5 h, preceded by association of IKKbeta with the Src/EGFR complex and increased phospho-IkappaBalpha in MDA-MB468 cells. TNFalpha increased I3C-induced apoptosis in MDA-MB-468 and MDA-MB-231 cells. It also induced apoptosis, enhanced by I3C, in HBL100 cells. Hence, regulation of constitutive NF-kappaB was cell-specific. I3C influenced the NF-kappaB pathway in a cell-specific manner, which was not related to apoptosis. However, the combination of I3C and TNFalpha increased apoptosis in all cell lines.
Moiseeva
Elena P
EP
Departments of Biochemistry and Cancer Studies, Cancer Biomarkers and Prevention Group, Biocentre, University of Leicester, Leicester, LE1 7RH, UK. em9@le.ac.uk
Heukers
Raimond
R
D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D005260:Female; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016588:Anticarcinogenic Agents; D002867:Chromones; D007211:Indoles; D009025:Morpholines; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D004247:DNA; C016517:indole-3-carbinol