Hypoxia induces p53-dependent transactivation and Fas/CD95-dependent apoptosis

Abstract

p53 triggers apoptosis in response to cellular stress. We analyzed p53-dependent gene and protein expression in response to hypoxia using wild-type p53-carrying or p53 null HCT116 colon carcinoma cells. Hypoxia induced p53 protein levels and p53-dependent apoptosis in these cells. cDNA microarray analysis revealed that only a limited number of genes were regulated by p53 upon hypoxia. Most classical p53 target genes were not upregulated. However, we found that Fas/CD95 was significantly induced in response to hypoxia in a p53-dependent manner, along with several novel p53 target genes including ANXA1, DDIT3/ GADD153 (CHOP), SEL1L and SMURF1. Disruption of Fas/CD95 signalling using anti-Fas-blocking antibody or a caspase 8 inhibitor abrogated p53-induced apoptosis in response to hypoxia. We conclude that hypoxia triggers a p53-dependent gene expression pattern distinct from that induced by other stress agents and that Fas/CD95 is a critical regulator of p53-dependent apoptosis upon hypoxia. The tumor suppressor p53 regulates cellular processes such as cell cycle progression, DNA repair and apoptosis. 1 p53 is stabilized and activated in response to different types of cellular stress, for example, DNA damage, oncogenic signalling and hypoxia, and induces a biological response through transcriptional regulation of downstream target genes. The molecular mechanisms that dictate the decision of a cell to enter growth arrest or undergo apoptosis or both in response to p53 activation are only partially understood. Also, it remains unclear why different cell types display differential response to functional p53. The biological outcome of p53 activation presumably depends on several factors, including cellular context, cell type and type of stress agent. 1 It is plausible that p53 activates different specific and possibly overlapping set of target genes in response to different stress signals. Therefore, knowledge about the target genes and their regulation under different conditions is vital for the understanding of p53-mediated tumor suppression.Previous DNA microarray studies have allowed a global analysis of p53-dependent gene expression in response to p53 activation by various means. 2,3 These studies have indicated that several hundred genes are potentially regulated by p53. Moreover, in silico analysis of the human genome sequence has revealed that up to 4800 genes contain one or more potential p53 binding sites. 4,5 Thus, it is conceivable that a large number of genes are regulated by p53, although not necessarily in the same cell in response to the same stress signal. Microarray studies have so far relied on artificial cell systems for activation of p53, for example, the metallothionein promoter or expression of exogenous p53. In addition, the numbers of genes on the arrays used have been relatively low. Thus, further studies of p53-dependent gene expression based on activation of endogenous p53 in response to physiological cellular stress should provide more reliable information about p53-dependent stress respon...

15-deoxy-Δ12,14-prostaglandin J2 up-regulates death receptor 5 gene expression in HCT116 cells: involvement of reactive oxygen species and C/EBP homologous transcription factor gene transcription

“…This assumption was based on the facts that, different from LNCaP cells, PC3 cells are p53-null, and the p53 binding site is positioned at the -1,847 site of the human CHOP promoter (33). To address this issue, we did experiments in wild-type and p53-null HCT116 cells and treated cells with different ER stressors.…”

“…Although p53-independent CHOP up-regulation was shown (48,49), CHOP was shown to be a p53 target gene on encountering stress like hypoxia (33) and DNA damage (50). To further elucidate the exact case for 15dPGJ 2 , especially under a situation showing inconsistent CHOP induction in 15dPGJ 2 -treated HCT116 (p53-containing) and PC3 (p53-null) cells, we therefore compared the CHOP induction responses in wild-type and p53-null HCT116 cells.…”

AmotL2 disrupts apical–basal cell polarity and promotes tumour invasion

“…The reported regulation of AmotL2 by hypoxia and its effect on cellular migration prompted us to analyse the expression pattern of AmotL2 in human cancer 15,[22][23][24] . AmotL2 protein expression was detected by immunohistochemical staining of paraffin-embedded sections from breast and colon cancer patients.…”

Synthesis of cytochrome c oxidase 2: a p53-dependent metabolic regulator that promotes respiratory function and protects glioma and colon cancer cells from hypoxia-induced cell death

“…No p53 was detectable in HCT116 p53 À/À cells. As conflicting results concerning transcriptional activity of p53 under hypoxia exist (Liu et al, 2007;Zhao et al, 2009), p53 transactivation activity under the experimental conditions was analyzed by luciferase assay. The p53-transactivation capacity was significantly reduced in p53-depleted cells (LNT-229 p53sh, LNT-229 p53ts and HCT116 p53 À/À ) at all experimental conditions (Figure 1b).…”