p53 inhibition of AP1-dependent TFF2 expression induces apoptosis and inhibits cell migration in gastric cancer cells

Abstract

Overexpression of trefoil factor 2 (TFF2) is associated with increased cell migration, resistance to apoptosis, and possibly increased gastric cancer invasion. Dysregulation of p53 is frequently observed in preneoplastic conditions of the stomach. Here, we investigated the effect of p53 on the expression and function of TFF2 in gastric cancer cell lines. Gene expression was determined by reverse transcription-polymerase chain reaction, and promoter activity was assessed by dual luciferase reporter assays. Apoptosis was detected by flow cytometry, and cell migration was evaluated by the Boyden chamber assay. Exogenous expression of p53 dose dependently inhibited endogenous TFF2 mRNA, protein, and promoter activity and resulted in induction of cell apoptosis and inhibition of cell migration. Downregulation of TFF2 by small interfering RNA sensitized gastric cancer cells to drug-induced p53-dependent apoptosis. Addition of human TFF2 peptide reversed p53-dependent apoptosis and inhibition of cell migration. The p53-responsive element was mapped to an AP-1-like cis-element at -182 bp upstream of the TFF2 transcription start site. Mutation of this AP-1-like element abrogated p53-mediated inhibition of TFF2 promoter activity. Gel shift and chromatin immunoprecipitation assays demonstrated that c-Jun and c-Fos bind to this AP-1-like element. Ectopic expression of c-Jun/c-Fos or p300 or treatment of cells with phorbol 12-myristate 13-acetate (PMA) stimulated endogenous TFF2 mRNA expression and promoter activity, and p53 inhibited the effects of AP-1 and PMA on TFF2. p53 induces cell apoptosis and inhibits cell migration in part by downregulating TFF2 expression through an AP-1-like site, suggesting that TFF2 may be an important downstream target of p53.

A Comprehensive and High-Resolution Genome-wide Response of p53 to Stress

“…Other positional relationships included factors involved in environmental stress and oncogenesis such as AP1, NRF2, FOXO3 and ETS/SPI1/PU.1, and pluripotent stem cell maintenance such as Oct4, Sox2, Klf4, and Myc, or related family members. A number of these factors have been demonstrated to have functional interrelationships with p53 (Renault et al, 2011; Rotblat et al, 2012; Tu et al, 2009; Zhu et al, 2006). Approximately 1,000 paired genomic features were identified ( Table S2 ).…”

IFN-γ Inhibits Gastric Carcinogenesis by Inducing Epithelial Cell Autophagy and T-Cell Apoptosis

“…A 950 bp fragment of the Beclin 1 promoter was cloned into the pGL3-Basic vector through PCR amplification from human genomic DNA (Promega) using synthetic primers (23). MKN-28 cells (1.0×10 5 cells/12-well) were transfected with 1.5 μg Beclin 1-luciferase or 1.5μg empty reporter vector DNA using the FuGene HD transfection reagent (Promega).…”

“…After 6 hours, the transfected cells were cultured either with or without 20ng/ml IFN-γ for 24-hours. Luciferase activity was determined as previously described (23). All assays were performed in triplicate and repeated three times.…”

Tumor suppressor XAF1 induces apoptosis, inhibits angiogenesis and inhibits tumor growth in hepatocellular carcinoma

“…XIAP has been shown to be overexpressed in most human cancer cell lines and cancer tissues including HCC tissues. Its overexpression has been demonstrated to be the independent factor for predicting the poor prognosis of HCC patients after liver transplantation [8]. Studies have shown that XIAP antisense nucleic acid and small molecule inhibitors of XIAP induce apoptosis and inhibit tumor growth in HCC cells [9], indicating that targeting inhibition of XIAP may be a new approach for HCC therapy [10].…”