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Genes induced by exposure to adriamycin. A coherent cluster of 45 genes induced in response to adriamycin treatment in MEFs is shown. See Results and Materials and Methods for experimental details.
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Hypoxia is an important nongenotoxic stress that modulates the tumor suppressor activity of p53 during malignant progression.
In this study, we investigated how genotoxic and nongenotoxic stresses regulate p53 association with chromatin, p53 transcriptional
activity, and p53-dependent apoptosis. We found that genotoxic and nongenotoxic stresses res...
Contexts in source publication
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... targets involved in cell cycle regulation and apoptosis, for example, Perp and Apaf-1. Interestingly, of all the genes in- duced by adriamycin treatment, 92% were induced in a p53- dependent manner ( Fig. 2; see Fig. S1 in the supplemental material). In contrast, the list of genes induced by p53 in response to hypoxia did not contain any genes previously known to induce apoptosis or cell cycle arrest in a p53-depen- dent manner, except p21 (see Fig. S1 in the supplemental material). In particular, the levels of the proapoptotic genes ...
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... S1 in the supplemental material). In particular, the levels of the proapoptotic genes Noxa, Perp, Bax, and Puma were not elevated in response to hypoxia, or their expression was low and unchanged. We fur- ther investigated genes that appeared to be induced in a p53- dependent manner in response to hypoxia by Northern blotting and qRT-PCR (see Fig. S2 in the supplemental material). Of the genes analyzed, none were induced by hypoxia in a p53- dependent manner. In fact, these genes scored as inducible because their expression was maintained under hypoxia in a p53-dependent manner. For example, both Dusp 6 and Myc showed reduced mRNA levels in hypoxia in the absence of p53, indicating ...
Citations
... Both DNA damage repair and apoptosis can reduce the damage caused by hypoxia (such as brain tissue damage) in subterranean rodents. These two pathways are considered the molecular regulation pathways of tumor suppression in subterranean rodents, which are induced by hypoxia or DNA damage , Johnson et al. 2005, Morgunkova 2005, Hammond et al. 2006, Prabha et al. 2012. ...
The response mechanism and interaction patterns of HIF-1α and p53 in animals in an hypoxic environment are crucial for their hypoxic tolerance and adaptation. Many studies have shown that underground rodents have better hypoxic adaptation characteristics. However, the mechanism by which HIF-1α and p53 in underground rodents respond to hypoxic environments compared with in ground rodents remains unclear. Further, whether a synergy between HIF-1α and p53 enables animals tolerate extremely hypoxic environments is unclear. We studied HIF-1α and p53 expression in the brain tissue and cell apoptosis in the hippocampal CA1 region during 6 hours of acute hypoxia (5% oxygen) in Lasiopodomys mandarinus (Milne-Edwards, 1871) and Lasiopodomys brandtii (Radde, 1861), two closely related small rodents with different life characteristics (underground and aboveground, respectively), using a comparative biology method to determine the mechanisms underlying their adaptation to this environment. Our results indicate that HIF-1α and p53 expression is more rapid in L. mandarinus than in L. brandtii under acute hypoxic environments, resulting in a significant synergistic effect in L. mandarinus . Correlation analysis revealed that HIF-1α expression and the apoptotic index of the hippocampal CA1 regions of the brain tissues of L. mandarinus and L. brandtii , both under hypoxia, were significantly negatively and positively correlated, respectively. Long-term existence in underground burrow systems could enable better adaptation to hypoxia in L. mandarinus than in L. brandtii . We speculate that L. mandarinus can quickly eliminate resulting damage via the synergistic effect of p53 and HIF-1α in response to acute hypoxic environments, helping the organism quickly return to a normal state after the stress.
... The different fold change in expression of p53 target genes, such as MDM2, BAX, and DRAM1 ( Figures 2.13, 2.14 and 2.18), when p53 protein recovered in SiHa and CaSki cells may be due to the different amounts of recovered p53 protein in these cells (Figure 2.2). Furthermore, the transactivation activity of hypoxia-induced p53 was impaired under hypoxia [296,[302][303][304][305]. The transactivation activity of p53 under prolonged hypoxia in SiHa and CaSki cells may be different, thereby resulting in different transcript levels of p53 target genes. ...
The tumor suppressor p53 primarily functions as a transcription factor responding to a myriad of cellular stresses. It is a pivotal and pleiotropic regulator in the stress-induced cellular response networks. Diverse activities of p53 are important not only in DNA repair, induction of cell cycle arrest and apoptosis, but also in senescence, autophagy and metabolism. In cells infected with human papillomaviruses (HPVs), the viral oncoproteins E6 and E7 target the tumor suppressors p53 and pRb, respectively, for degradation and inactivation. HPV E6 and E7 synergistically act to promote uncontrolled cell divisions and inhibit apoptosis. Persistent infections with high-risk HPVs are closely linked to cervical cancer as well as other malignancies in the anogenital and oropharyngeal region. Our previous lab results found that HPV E6/E7 oncogenes are repressed under hypoxia, a condition that is frequently detected in solid tumors. Unlike the reactivation of pRb, p53 protein levels did not increase in E6/E7-repressed hypoxic HPV16-positive cancer cells, but even decreased further. The present study aimed to delineate the dynamics of p53 under hypoxic conditions as well as the mechanisms underlying this regulation and elucidate the role of p53 regulation for downstream responses and cellular outcomes/fates in hypoxic HPV16-positive cancer cells. It was revealed that despite a continuous repression of E6/E7 oncogenes, p53 did not immediately recover, but instead showed a biphasic regulation (rapid and strong depletion, then marked recovery). The initial hypoxic reduction of p53 was predominantly mediated via a lysosome-dependent mechanism. The biphasic regulation of p53 appears to serve as a survival and protective strategy of hypoxic HPV16-positive cancer cells under stress conditions. The modulation on p53 downstream target genes that coincides with p53 protein dynamics may contribute to enhance cellular adaptation to hypoxia. p53 target genes associated with terminal fates such as cell death (apoptosis) and permanent cell cycle arrest (senescence) are inactivated through p53 depletion by hypoxia, protecting cells from committing to an irreversible fate. After prolonged hypoxia, the restored p53 might be required by HPV16-positive cancer cells to maintain cellular homeostasis and select cells resistant to cell death by induction of apoptotic genes. Hypoxia-associated initial reduction of p53 facilitates the induction of autophagy, which is critical for the evasion of senescence by hypoxic HPV16-positive cancer cells. Collectively, these findings reveal a new regulation pattern of p53 by hypoxia and provide new insights into the role of p53 regulation in downstream responses and cellular adaptation to hypoxia in HPV16-positive cancer cells. This study further has implications for the development of new treatment strategies.
... suggesting a potential tumour-suppressor role [68]. In accordance, studies of astrocytes, human lung cancer cells, and mouse embryonic fibroblasts characterize DGKα as a gene up-regulated by the tumour suppressor p53 that is mutated in the majority of cancers [69]. Conversely, other reports suggested that the growth of colon and breast cancer cell lines was significantly inhibited by DGKα-siRNA [70] and DGKα/atypical PKC/β1 integrin signalling pathway was crucial for matrix invasion of breast cancer cells [60]. ...
Diacylglycerol kinases (DGKs) comprise a multigenic family of enzymes phosphorylating diacylglycerol (DAG) to phosphatidic acid (PA). Multiple findings suggest that activation of DGKα may play a key role in cancer by showing pro-tumoural and anti-immunogenic properties. Moreover, its inhibition impairs cancer cell viability, blocks the angiogenetic process and, remarkably, increases the T cells activation. Conversely, overactivation of DGKα is observed in X-linked lymphoproliferative disease type 1 (XLP1), a primary immunodeficiency of genetic origin characterized by hemophagocytic lymphohistiocytosis (HLH) and defective restimulation induced cell death (RICD). DGKα dysregulation is a key event for XLP1 pathogenesis, as pharmacological inhibition or silencing of DGKα in XLP1 lymphocytes restores RICD. Furthermore, DGKα inhibitors limit CD8+ T cell expansion and interferon-γ (INFγ) production in XLP1 animal models, suggesting the development of DGKα inhibitors for XLP1 therapy.
As the available DGKα inhibitors are poorly specific and have low activity, we aim to identify new DGKα inhibitors with translational potential. Thus, we used an in-silico approach based on chemical homology with the two commercially available DGKα inhibitors R59022 and R59949. The best scoring compounds were tested for their inhibitory activity. Out of 147 molecules tested, Amb639752 emerged out as a lead compound, showing an inhibitory activity superior to the commercial inhibitors and specificity for the alpha isoform. Interestingly, Amb639752 was also devoid of activity on serotonin receptors indicating superior specificity. Thus, we executed compound optimization of Amb639752 that yielded 6 novel active compounds that are highly specific to DGKα and do not perturb serotonin signalling. Our studies also allow us to set a three-point pharmacophore model for the development of DGK inhibitors.
After demonstrating their activity in vitro, we tested the most active compounds in biological assays using SAP silenced lymphocytes as XLP1 model and MCF-7 cells as a model for carcinoma cell migration. We could demonstrate their ability to restore RICD in SAP deficient lymphocytes as well as the capacity to reduce the migration of cancer cells. Those results suggest the potential utility of the DGKα inhibitors we discovered in XLP1 therapy and in carcinoma therapy.
Concluding, we identified a new generation of specific DGKα inhibitors that may contribute to the development of innovative therapies for diseases characterized by RICD resistance such as XLP1 but also have potential utility in different metastatic cancer models.
... Intuitively, induction of p53 during hypoxia should balance some of the metabolic effects mediated by HIF1a. However, the p53 response to mild hypoxic conditions seems to be initially biased towards a subset of its repressed target genes, a process implicating the mSin3a corepressor [175]. Competition between HIF1a and p53 for common transcriptional co-activators such as CBP/p300 and specific posttranslational modifications of p53 also seem to play a role in p53's ability to regulate a subset of its target genes during hypoxia [176,177]. ...
Background:
The TP53 gene is one of the most commonly inactivated tumor suppressors in human cancers. p53 functions during cancer progression have been linked to a variety of transcriptional and non-transcriptional activities that lead to the tight control of cell proliferation, senescence, DNA repair, and cell death. However, converging evidence indicates that p53 also plays a major role in metabolism in both normal and cancer cells.
Scope of review:
We provide an overview of the current knowledge on the metabolic activities of wild type (WT) p53 and highlight some of the mechanisms by which p53 contributes to whole body energy homeostasis. We will also pinpoint some evidences suggesting that deregulation of p53-associated metabolic activities leads to human pathologies beyond cancer, including obesity, diabetes, liver, and cardiovascular diseases.
Major conclusions:
p53 is activated when cells are metabolically challenged but the origin, duration, and intensity of these stresses will dictate the outcome of the p53 response. p53 plays pivotal roles both upstream and downstream of several key metabolic regulators and is involved in multiple feedback-loops that ensure proper cellular homeostasis. The physiological roles of p53 in metabolism involve complex mechanisms of regulation implicating both cell autonomous effects as well as autocrine loops. However, the mechanisms by which p53 coordinates metabolism at the organismal level remain poorly understood. Perturbations of p53-regulated metabolic activities contribute to various metabolic disorders and are pivotal during cancer progression.
... In contrast, we along with others have reported that chronic hypoxiainduced p53 has little or no transcriptional capabilities and that hypoxic p53 loses key post-translational modifications which result in a transcriptionally inactive, conformational mutant phenotype for both WT and MT p53 molecules under physiologically relevant hypoxia of 1.8% O2 (11,54,63,64). Thus, p53 was found to be both responsible and indispensable for apoptosis under hypoxia (8,12,(65)(66)(67)(68)(69)(70)(71). It is likely that the use of random oxygen concentrations ranging from anoxia to 5% O2, use of chemical stimulants for hypoxia and degree of reoxygenation, are possible reasons for these inconsistencies. ...
Chronic hypoxia is associated with a variety of physiological conditions such as rheumatoid arthritis, ischemia/reperfusion injury, stroke, diabetic vasculopathy, epilepsy and cancer. At the molecular level, hypoxia manifests its effects via activation of HIF-dependent transcription. On the other hand, an important transcription factor p53, which controls a myriad of biological functions, is rendered transcriptionally inactive under hypoxic conditions. p53 and HIF-1α are known to share a mysterious relationship and play an ambiguous role in the regulation of hypoxia-induced cellular changes. Here we demonstrate a novel pathway where HIF-1α transcriptionally upregulates both WT and MT p53 by binding to five response elements in p53 promoter. In hypoxic cells, this HIF-1α-induced p53 is transcriptionally inefficient but is abundantly available for protein-protein interactions. Further, both WT and MT p53 proteins bind and chaperone HIF-1α to stabilize its binding at its downstream DNA response elements. This p53-induced chaperoning of HIF-1α increases synthesis of HIF-regulated genes and thus the efficiency of hypoxia-induced molecular changes. This basic biology finding has important implications not only in the design of anti-cancer strategies but also for other physiological conditions where hypoxia results in disease manifestation.
... Furthermore, BCL-2/adenovirus E1B 19kDa interacting protein 3 (Bnip3) was identified as a p53 target activated under hypoxia, which is different from those normally activated by DNA-damaging agents, and responsible for p53-mediated apoptosis following hypoxic stress (Fei et al., 2004). By genomic analysis of p53 in hypoxia it was shown that hypoxia-induced p53 primarily has repressive activity, repressing target genes involved in diverse signaling pathways including cell signaling, cell cycle control and differentiation (Hammond et al., 2006). ...
... Indeed, consistent with the previously reported negative regulation of wt p53 on HIF-1α stability, depletion of wt p53 increased normoxic levels of HIF-1α (SI Appendix, Fig. S2E). These last results were in agreement with previous studies, reporting the hypoxia-dependent stabilization of wt p53 (19,20), a negative regulation of HIF-1α stability following physical binding to wt p53 (21)(22)(23), and an involvement of this interplay in p53-mediated hypoxic cell death (24)(25)(26). ...
Significance
Expression in cancer cells of novel proteins generated by mutations in the TP53 gene is an important prognostic factor; however, how p53 mutants promote cancer progression is largely unknown. Here, we describe a molecular mechanism of gain-of-function by mutant p53 in hypoxic non-small cell lung cancer (NSCLC) cells. We identified the existence of a hypoxia-inducible factor-1 (HIF-1)/mutant p53 complex, exerting transcriptional control of a specific subset of protumorigenic genes, codifying for extracellular matrix (ECM) components. Employing in vivo cancer models and analyzing clinical material, we demonstrate that these ECM components substantially contribute to the synergistic protumorigenic activity of p53 mutants and HIF-1. Our data indicate that HIF-1/mutant p53 cross-talk is an innovative potential therapeutic target to treat advanced NSCLC.
... Previous studies have demonstrated that hypoxia exposure induces and activates p53 and thus promotes apoptosis, indicating the primary role of p53 as a pro-apoptotic factor under hypoxic conditions (16,26,27). Leszczynska et al (28) reported that hypoxia-induced p53 targets several downstream target genes, including inositol polyphosphate-5-phosphatase (INPP5D), pleckstrin domain-containing A3 (PHLDA3), sulfatase 2 (SULF2), B cell translocation gene 2 (BTG2), cytoplasmic FMR1-interacting protein 2 (CYFIP2), and KN motif and Ankyrin repeat domains 3 (KANK3); consequently, p53 mediated tumor suppression (28). ...
Lung cancer is one of the most frequently occurring and fatal cancer types worldwide. Cisplatin is widely used for chemotherapy of non-small cell lung cancer (NSCLC). However, the use of cisplatin has been met with the challenge of chemoresistance as a result of hypoxia, which is common in adult solid tumors and is a principal cause of a poor patient outcome. In the present study, the effects of hypoxia on the response of the NSCLC A549 cell line to the clinically relevant cytotoxic cisplatin were evaluated via regulating hypoxia inducible factor-1α (HIF-1α) and p53. Hypoxia exposure upregulated the expression levels of HIF-1α and p53, and promoted glycolysis in A549 cells, which was attenuated by HIF-1α knockdown by siRNA introduction, indicating the critical roles of HIF-1α in regulating glycolysis under hypoxic conditions. HIF-1α-knockdown also sensitized A549 cells to cisplatin in hypoxia-exposed, but not in normoxia-exposed A549 cells, suggesting that hypoxia-induced cisplatin resistance partially contributes toward the upregulation of HIF-1α by hypoxia exposure. The present study also determined that hypoxia-upregulated p53 activated its downstream target gene p21 transcriptionally and blocked the cell cycle at the G1-G0 phase, thereby leading to inhibition of cell proliferation. As a result, activated p53 desensitized A549 cells to cisplatin potentially through increasing the non-proliferation status of A549 cells and therefore minimizing the influence of cisplatin. Taken together, these results identified the exact effects of HIF-1α and p53 induced by hypoxia and potentially elucidated their protective effects on A549 cells against cisplatin.
... These data suggested that prolonged hypoxia renders cells replication incompetent. A number of genes involved in DNA replication and repair have been found to be repressed in hypoxic conditions including members of the minichromosome maintenance complex (MCM) family [51,52]. The MCM2-7 complex is loaded onto chromatin in the G 1 phase of the cell cycle and provides the essential helicase activity necessary for duplex unwinding during replication [20]. ...
The term hypoxia refers to any condition where insufficient oxygen is available and therefore encompasses a range of actual oxygen concentrations. The regions of tumours adjacent to necrotic areas are at almost anoxic levels and are known to be extremely therapy resistant (radiobiological hypoxia). The biological response to radiobiological hypoxia includes the rapid accumulation of replication stress and subsequent DNA damage response, including both ATR and ATM-mediated signalling, despite the absence of detectable DNA damage. The causes and consequences of hypoxia-induced replication stress will be discussed. This article is protected by copyright. All rights reserved.
... Consequently, 44 genes were selected as p53-repressed gene candidates ( Figure 1D, Supplementary Figure S1). Among them, 17 genes (AURKB [13], BIRC5 [14], CCNA2 [15], CCNB1 [15], CCNB2 [16], CDC20 [17], CDCA8 [18], CENPA [19], CEP55 [20], KIF23 [21], LMNB1 [22], MCM5 [23], PLK1 [24], RACGAP1 [25], RRM2 [26], TOP2A [27], and UBE2C [28]) have been reported as being p53-repressed genes with experimental verification. ...
The p53 protein is a sophisticated transcription factor that regulates dozens of target genes simultaneously in accordance with the cellular circumstances. Although considerable efforts have been made to elucidate the functions of p53-induced genes, a holistic understanding of the orchestrated signaling network repressed by p53 remains elusive. Here, we performed a systematic analysis to identify simultaneously regulated p53-repressed genes in breast cancer cells. Consequently, 28 genes were designated as the p53-repressed gene module, whose gene components were simultaneously suppressed in breast cancer cells treated with Adriamycin. A ChIP-seq database showed that p53 does not preferably bind to the region around the transcription start site of the p53-repressed gene module elements compared with that of p53-induced genes. Furthermore, we demonstrated that p21/CDKN1A plays a pivotal role in the suppression of the p53-repressed gene module in breast cancer cells. Finally, we showed that appropriate suppression of some genes belonging to the p53-repressed gene module contributed to a better prognosis of breast cancer patients. Taken together, these findings disentangle the gene regulatory network underlying the built-in p53-mediated tumor suppression system.
