title: Induction of GADD gene expression by phenethylisothiocyanate in human colon adenocarcinoma cells.
abstract: Phenethylisothiocyanate (PEITC), a potential cancer chemopreventive agent, induces colon cancer cell death, but the mechanism is not entirely clear. Therefore, the aim of this study was to further clarify the molecular effects of PEITC in causing death of human colon adenocarcinoma cells. When incubated with PEITC, HCT-116 colonocytes showed morphological features characteristic of apoptosis, such as irregular cell shape, translocation of plasma membrane phosphatidylserine, and also chromatin condensation and fragmentation. These changes occurred after single-strand breaks in DNA were detected, suggesting that PEITC induced irreparable DNA damage, which in turn triggered the process of apoptosis. DNA macroarray analysis of a selected small cluster of apoptosis-related genes revealed noticeably higher expression of only GADD45, which was confirmed by gene-specific relative RT-PCR analysis. This led to investigation of other GADD gene members possibly affected by PEITC. Whereas GADD34 mRNA expression increased just slightly, there was an appreciable elevation of the mRNA for GADD153, which is recognized as a pro-apoptotic gene. The effect of PEITC on GADD153 was attenuated by either actinomycin D or N-acetylcysteine, suggesting that PEITC-induced upregulation of GADD153 mRNA expression was partly at the level of transcriptional activation involving reactive oxygen species. Additionally, PEITC-induced upregulation of GADD153 mRNA expression did not appear to require p53, based on the observation that PEITC also increased GADD153 mRNA expression in HCT-15 colonocytes, which are known to express mutant p53. These findings suggest that PEITC creates an oxidative cellular environment that induces DNA damage and GADD153 gene activation, which in turn helps trigger apoptosis.
authors.affiliation: Cellular and Molecular Nutrition Research Laboratory, Graduate Program in Nutrition, The University of North Carolina at Greensboro, Greensboro, North Carolina 27402-6170, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Powolny
authors.forename: Keiko
authors.initials: K
authors.lastname: Takahashi
authors.forename: Robin G
authors.initials: RG
authors.lastname: Hopkins
authors.forename: George
authors.initials: G
authors.lastname: Loo
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000943:Antigens, Differentiation; D017209:Apoptosis / Q000187:drug effects; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D048429:Cell Size; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates / Q000494:pharmacology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D054645:Protein Phosphatase 1; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D000097642:GADD45 Proteins
chemical_list: D000111:Acetylcysteine; D016588:Anticarcinogenic Agents; D000943:Antigens, Differentiation; D022762:CCAAT-Enhancer-Binding Proteins; D018797:Cell Cycle Proteins; D003609:Dactinomycin; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates; D019384:Nucleic Acid Synthesis Inhibitors; D054645:Protein Phosphatase 1; D011506:Proteins; D012333:RNA, Messenger; D051742:Transcription Factor CHOP; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D000097642:GADD45 Proteins; C497249:DDIT3 protein, human; C058305:phenethyl isothiocyanate; C087519:PPP1R15A protein, human