title: Selenomethionine regulates cyclooxygenase-2 (COX-2) expression through nuclear factor-kappa B (NF-kappaB) in colon cancer cells.
abstract: Previously, we showed that selenomethionine (Se-Met) inhibits growth of colon cancer cells via suppressing COX-2 expression at both mRNA and protein level. However, the molecular mechanism by which Se-Met suppresses COX-2 expression remains to be elucidated. To this end, we transiently transfected HCA-7 cells with different COX-2 promoter constructs followed by Se-Met treatment (90 microM) for 12 h. The results suggested the role of nuclear factor-kappa B (NF-kappaB) in transcriptional regulation of COX-2. We also observed complete inhibition of DNA binding activity of NF-kappaB in Se-Met (90 microM) treated HCA-7 cells as shown by electrophoretic mobility shift assay (EMSA). Supershift assays with anti-p65 antibody identified p65 subunit in the protein complex. We further demonstrate dose-dependent inhibition of nuclear translocation of NF-kappaB/p65 in Se-Met treated HCA-7 cells, which could explain the observed reduction in DNA binding of NF-kappaB/p65. These results suggest that Se-Met regulates COX-2 at transcriptional level by modulating the activity of NF-kappaB transcription factor.
authors.affiliation: Department of Pathology, Arizona Cancer Center, The University of Arizona College of Medicine, Tucson, Arizona 85724, USA.
authors.forename: Durga P
authors.initials: DP
authors.lastname: Cherukuri
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Goulet
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Inoue
authors.forename: Mark A
authors.initials: MA
authors.lastname: Nelson
mesh_terms: D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051546:Cyclooxygenase 2; D024202:Electrophoretic Mobility Shift Assay; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D008565:Membrane Proteins; D016328:NF-kappa B / Q000235:genetics*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012645:Selenomethionine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D008565:Membrane Proteins; D016328:NF-kappa B; D012645:Selenomethionine; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases