Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Conditionally replicative adenoviruses (CRAd) are under investigation as anticancer agents. Previously, we found that the CRAd AdDelta24-p53, expressing the p53 tumor suppressor protein from its genome, more effectively killed most human cancer cells than did its parent AdDelta24. However, a minority of cancer cell lines poorly responded to the oncolysis-enhancing effect of p53. Here we show that refractory cell lines expressed high levels of the major negative p53 regulator murine double minute 2 (MDM2). To obviate MDM2-mediated inactivation of CRAd-encoded p53, we constructed the new CRAd AdDelta24-p53(14/19) encoding a p53 variant incapable of binding to MDM2. AdDelta24-p53(14/19) was approximately 10 times more effective than AdDelta24-p53 in killing cancer cell lines with high levels of human MDM2, but not cells with low MDM2. This finding supports the notion that exogenous expression of functional p53 augments the anticancer efficacy of CRAds. In addition, it confirms that high MDM2 expression is a molecular determinant of resistance against oncolysis enhancement by exogenous wild-type p53. Moreover, it shows that efficacy enhancement by restoration of functional p53 can also be accomplished in cancer cells expressing a p53 inhibitor. This further expands the utility of CRAds expressing functional p53 variants for effective virotherapy of cancer and thus their possible contribution to the advancement of individualized molecular medicine.
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PMID:Conditionally replicative adenovirus expressing degradation-resistant p53 for enhanced oncolysis of human cancer cells overexpressing murine double minute 2. 1595 59

An adenovirus (Adv) retaining normal E1A but lacking the 55 kDa E1B protein replicates preferentially in TP53-deficient cancer cells including pancreatic cancer cell lines, resulting in the oncolysis of the tumor. When tumor cells are exposed to hypoxia, hypoxia-inducible factor-1alpha (HIF-1alpha) is stabilized and activated to promote the transcription of several genes such as vascular endothelial growth factor (VEGF), but in the presence of E1A hypoxia-induced VEGF m-RNA synthesis is inhibited by E1A binding to p300. In this study, we demonstrated that the cancer cells infected with a mutant Adv in which the p300 binding site in E1A was partially deleted induced a higher expression level of VEGF as compared to those of Adv with normal E1A. An immunoprecipitation study for E1A confirmed that mutant E1A had a reduced binding capacity for p300. Although the expressions of HIF-1alpha m-RNA were almost the same in both cancer cells infected with the mutant Adv and those with the wild Adv, the amount of HIF-1alpha protein in cancer cells infected with the wild E1A Adv was lower than in those infected with the mutant E1A type Adv. In vivo, in contrast to the angiogenesis treated with mutant E1A, wild-E1A inhibited tumor angiogenesis significantly. These results suggested that E1A suppressed the production of VEGF and inhibited tumor angiogenesis by binding with p300, resulting in the inhibition of the HIF-1alpha-mediated transcription of genes through binding to HRE. This study demonstrates, for the first time, the effect of an oncolytic replication-competent Adv in inhibiting tumor angiogenesis.
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PMID:Oncolytic replication-competent adenovirus suppresses tumor angiogenesis through preserved E1A region. 1617 28

Colorectal tumors frequently contain activating mutations in KRAS. ReovirusT3D is an oncolytic virus that preferentially kills tumor cells with an activated Ras pathway. Here we have assessed the contribution of endogenous mutant KRAS in human colorectal cancer cell lines to ReovirusT3D replication and to tumor cell oncolysis. In addition, treatment combinations involving ReovirusT3D, oxaliplatin, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were tested for their efficacy in tumor cell killing. The mutation status of KRAS did not predict the sensitivity of a panel of human colorectal cancer cell lines to ReovirusT3D. Virus replication was observed in all cell lines tested regardless of KRAS status and was not affected by deletion of endogenous mutant KRAS(D13). However, deletion of KRAS(D13) or p53 did reduce apoptosis induction by ReovirusT3D whereas deletion of beta-catenin(DeltaS45) had no effect. Likewise, KRAS(D13)- or p53-deficient cells display reduced sensitivity to oxaliplatin but not to death receptor activation by TRAIL. Finally, the treatment of colorectal cancer cells with ReovirusT3D combined with either oxaliplatin or TRAIL resulted in a nonsynergistic increase in tumor cell killing. We conclude that oncolysis of human tumor cells by ReovirusT3D is not determined by the extent of virus replication but by their sensitivity to apoptosis induction. Oncogenic KRAS(D13) increases tumor cell sensitivity to activation of the cell-intrinsic apoptosis pathway without affecting ReovirusT3D replication.
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PMID:KRAS(D13) Promotes apoptosis of human colorectal tumor cells by ReovirusT3D and oxaliplatin but not by tumor necrosis factor-related apoptosis-inducing ligand. 1670 68

Previously we demonstrated that the expression of fusogenic membrane proteins (FMG) of measles virus (MV-H/F) can synergistically enhance chemotherapy. In this study, we used median-effect analysis to evaluate whether the expression of respiratory syncytial virus (RSV-F), as well as vesicular stomatitis virus (VSV-G) can also synergistically enhance chemotherapy. Furthermore we elucidated by western blot analysis some molecular pathways that might be responsible for this effect. We showed in colorectal cancer cell lines that the expression of MV-H/F, but also of RSV-F, as well as VSV-G can synergistically enhance p53-independent clinically relevant chemotherapy (FOLFOX) over most of the cytotoxic dose range. In a subcutaneous HT-29 colorectal xenograft model, we demonstrated that the administration of replication-deficient adenovirus vectors encoding MV-H/F, RSV-F or VSV-G in combination with FOLFOX significantly enhanced treatment outcome when compared to the treatment with each compound individually. The anti-neoplastic efficacy of RSV-F was somewhat better than that of MV-H/F and both were statistically significantly more efficacious than VSV-G alone or in combination with chemotherapy. Treatment efficacy was further significantly improved when the replication-deficient FMG encoding vectors were trans-complemented for replication with a replication-restricted oncolytic adenovirus to improve tumor transduction efficiency. The combination of FMG expression, chemotherapy and trans-complementing oncolytic vectors resulted in a significantly better treatment efficacy than treatment with its components as single- or double-agent therapy. Our data indicates that FMG expression (i.e., RSV-F and MV-H/F) in combination with chemotherapy and viral oncolysis warrants further investigations.
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PMID:Mechanistic analysis and comparison of viral fusogenic membrane proteins for their synergistic effects on chemotherapy. 1990 15

Tumour necrosis factor-alpha (TNF-alpha) is a cytokine that is involved in many functions, including the inflammatory response, immunity and apoptosis. Some of the responses of TNF-alpha are mediated by caspase-1, which is involved in the production of the pro-inflammatory cytokines interleukin-1beta, interleukin-18 and interleukin-33. The molecular mechanisms involved in TNF-alpha-induced caspase-1 gene expression remain poorly defined, despite the fact that signaling by TNF-alpha has been well studied. The present study was undertaken to investigate the mechanisms involved in the induction of caspase-1 gene expression by TNF-alpha. Treatment of A549 cells with TNF-alpha resulted in an increase in caspase-1 mRNA and protein expression, which was preceded by an increase in interferon regulatory factor-1 and p73 protein levels. Caspase-1 promoter reporter was activated by the treatment of cells with TNF-alpha. Mutation of the interferon regulatory factor-1 binding site resulted in the almost complete loss of basal as well as of TNF-alpha-induced caspase-1 promoter activity. Mutation of the p53/p73 responsive site resulted in reduced TNF-alpha-induced promoter activity. Blocking of p73 function by a dominant negative mutant or by a p73-directed small hairpin RNA reduced basal as well as TNF-alpha-induced caspase-1 promoter activity. TNF-alpha-induced caspase-1 mRNA and protein levels were reduced when p73 mRNA was down-regulated by small hairpin RNA. Caspase-5 gene expression was induced by TNF-alpha, which was inhibited by the small hairpin RNA-mediated down-regulation of p73. Our results show that TNF-alpha induces p73 gene expression, which, together with interferon regulatory factor-1, plays an important role in mediating caspase-1 promoter activation by TNF-alpha.
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PMID:Tumor necrosis factor-alpha-induced caspase-1 gene expression. Role of p73. 1772 14

The patients with Crohn's disease (CD) have a 'leaky gut' manifested by an increase in intestinal epithelial tight junction (TJ) permeability. Tumour necrosis factor-alpha (TNF-alpha) is a proto-typical pro-inflammatory cytokine that plays a central role in intestinal inflammation of CD. An important pro-inflammatory action of TNF-alpha is to cause a functional opening of intestinal TJ barrier. Previous studies have shown that TNF-alpha increase in TJ permeability was regulated by an increase in myosin light chain kinase (MLCK) gene activity and protein expression. The major aim of this study was to elucidate the cellular and molecular mechanisms that mediate basal and TNF-alpha-induced increase in MLCK gene activity. By progressive 5' deletion, minimal MLCK promoter was localized between -313 to +118 on MLCK promoter. A p53 binding site located within minimal promoter region was identified as an essential determinant for basal promoter activity. A 4 bp start site and a 5 bp downstream promoter element were required for MLCK gene activity. TNF-alpha-induced increase in MLCK promoter activity was mediated by NF-kappaB activation. There were eight kappaB binding sites on MLCK promoter. The NF-kappaB1 site at +48 to +57 mediated TNF-alpha-induced increase in MLCK promoter activity. The NF-kappaB2 site at -325 to -316 had a repressive role on promoter activity. The opposite effects on promoter activity were due to differences in the NF-kappaB dimer type binding to the kappaB sites. p50/p65 dimer preferentially binds to the NF-kappaB1 site and up-regulates promoter activity; while p50/p50 dimer preferentially binds to the NF-kappaB2 site and down-regulates promoter activity. In conclusion, we have identified the minimal MLCK promoter region, essential molecular determinants and molecular mechanisms that mediate basal and TNF-alpha-induced modulation of MLCK promoter activity in Caco-2 intestinal epithelial cells. These studies provide novel insight into the cellular and molecular mechanisms that regulate basal and TNF-alpha-induced modulation of MLCK gene activity.
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PMID:Cellular and molecular mechanisms that mediate basal and tumour necrosis factor-alpha-induced regulation of myosin light chain kinase gene activity. 1836 37

The efficacy of adenovirus vector-based cancer gene therapy is controversial. Its uptake by cells in many cases requires the major receptor for adenoviruses, the coxsackievirus and adenovirus receptor (CAR). Low transduction is believed to be one of the main barriers as the expression of CAR on tumor cells is frequently reduced. Increasing CAR expression on tumor cells thus offers a promising opportunity for more effective adenovirus based treatment. Expression of CAR in 62 cases of colon tumor specimens were examined with immunohistochemistry. To modify the CAR expression, the effects of proteasome inhibitor MG132 on CAR expression of colon cancer cell lines were determined by flow cytometry, RT-PCR, and western blot. To evaluate adenovirus transfer, we further used rAd.EGFP, rAd.p53, and oncolytic adenovirus to infect target cells. The CAR expression was significantly decreased in colon carcinomas, both in primary tumors and lymphonode metastasis. Though the deregulation of CAR occurred in early disease and showed no relationship with TNM stage, when primary tumors are more than 5 cm in diameter, this deregulation becomes more frequent. More importantly, proteasome inhibitor MG-132 could enhance CAR expression in colon carcinoma cell line lovo, accompanied with enhanced adenovirus transfer, target gene expression, and oncolysis. These data provide a rational basis for evaluation of CAR expression in tumors and pretreatment with CAR conditioner prior to adenovirus vector-based gene therapy.
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PMID:Proteasome inhibitor MG-132 modifies coxsackie and adenovirus receptor expression in colon cancer cell line lovo. 1841 65

Conditionally replicating adenoviruses (CRAd) can replicate specifically in cancer cells and lyse them. The CRAds were widely used in the preclinical and clinical studies of cancer therapy. We hypothesize that more precisely regulated replication of CRAds may further improve the vector safety profile and enhance its antitumor efficacy. Here, a triple-regulated CRAd carrying p53 gene expression cassette, SG600-p53, was engineered. In SG600-p53, the E1a gene with a deletion of 24 nucleotides within CR2 region is controlled under the human telomerase reverse transcriptase (hTERT) promoter, the E1b gene expression is directed by the hypoxia response element (HRE), whereas the p53 gene is controlled by the cytomegalovirus promoter. The precise triple-regulation endows SG600-p53 with enhanced antitumor potential and improved safety profile. The tumor-selective replication of this virus and its antitumor efficacy were characterized in several tumor cell lines in vitro and in xenograft models of human non-small cell lung cancer in nude mice. With the selective replication and oncolysis, it was found by ELISA assay that SG600-p53 expressed p53 efficiently in cancer cells. In NCI-H1299 tumor xenograft models, SG600-p53 displayed a tumor-selective killing capacity. At a dose of 2 x 10(9) plaque-forming units, SG600-p53 could completely inhibit the tumor growth and more effective than replication-defective Ad-p53. Histopathologic examination revealed that SG600-p53 administration resulted in cancer cell apoptosis. We concluded that the triple-regulated SG600-p53, as a more potent and safer antitumor therapeutic, could provide a new strategy for cancer biotherapy.
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PMID:A novel triple-regulated oncolytic adenovirus carrying p53 gene exerts potent antitumor efficacy on common human solid cancers. 1856 30

Selective replication-competent adenovirus serotype 5 vectors have been used for prostate cancer therapy. Unfortunately, gene transfer is inefficient because hormone-refractory metastatic prostate cancer cells have minimal coxsackievirus-adenovirus receptor expression. Vectors based on species B adenoviruses are attractive tools for use in human gene therapy because the viruses have low seroprevalence and they have efficient transduction capacity. Most species B adenoviruses use ubiquitously expressed complement-regulatory CD46 protein as a cellular receptor. Here we report the transduction efficacy and oncolytic capacity of a replication-competent Ad11p (RCAd11p) vector in human prostate cancer cells. Green fluorescent protein was efficiently expressed in a dose-dependent manner in PC-3 and DU 145 cells derived from metastasis of prostate cancer to bone and brain, respectively. However, transduction was less effective in LNCaP cells derived from prostate cancer metastasis to lymph nodes. The oncolytic capacity of the RCAd11p vector was 100 times higher in PC-3 cells than in the two other cell lines. The oncolysis was independent of the level of expression of p53 in the cells or on the absence of E1B55k expression in the vector. In vivo experiments revealed significant growth inhibition of PC-3 tumors in the xenograft mouse group treated with RCAd11p vector or Ad11pwt in comparison with the untreated control group. Thus, we have demonstrated that RCAd11p vector intrinsically possesses oncolytic properties, which were active in targeting tumor cells. Consequently, the novel RCAd11p vector has great potential for the treatment of incurable metastatic prostate disease.
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PMID:Replication-competent Ad11p vector (RCAd11p) efficiently transduces and replicates in hormone-refractory metastatic prostate cancer cells. 1919 89

Replication-competent oncolytic viruses hold great potential for the clinical treatment of many cancers. Importantly, many oncolytic virus candidates, such as reovirus and myxoma virus, preferentially infect cancer cells bearing abnormal cellular signaling pathways. Reovirus and myxoma virus are highly responsive to activated Ras and Akt signaling pathways, respectively, for their specificity for viral oncolysis. However, considering the complexity of cancer cell populations, it is possible that other tumor-specific signaling pathways may also contribute to viral discrimination between normal versus cancer cells. Because carcinogenesis is a multistep process involving the accumulation of both oncogene activations and the inactivation of tumor suppressor genes, we speculated that not only oncogenes but also tumor suppressor genes may have an important role in determining the tropism of these viruses for cancer cells. It has been previously shown that many cellular tumor suppressor genes, such as p53, ATM and Rb, are important for maintaining genomic stability; dysfunction of these tumor suppressors may disrupt intact cellular antiviral activity due to the accumulation of genomic instability or due to interference with apoptotic signaling. Therefore, we speculated that cells with dysfunctional tumor suppressors may display enhanced susceptibility to challenge with these oncolytic viruses, as previously seen with adenovirus. We report here that both reovirus and myxoma virus preferentially infect cancer cells bearing dysfunctional or deleted p53, ATM and Rb tumor suppressor genes compared to cells retaining normal counterparts of these genes. Thus, oncolysis by these viruses may be influenced by both oncogenic activation and tumor suppressor status.
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PMID:The viral tropism of two distinct oncolytic viruses, reovirus and myxoma virus, is modulated by cellular tumor suppressor gene status. 2047 28


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