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)

Current researches have proposed a genetic model for colorectal cancer (CRC), in which the sequential accumulation of mutations in specific cancer-related genes, including adenomatous polyposis coli (APC), K-ras, and p53, drives the transition from normal epithelium through increasing adenomatous dysplasia to colorectal cancer. To identify patients with an increased risk of tumor recurrence or metastasis and evaluate the prognostic values of APC, K-ras, and p53 gene mutations, we investigated the frequency of these three mutated genes in tumors and sera of CRC patients. APC, K-ras, and p53 gene mutations in primary tumor tissues and their paired preoperative serum samples of 118 CRC patients were detected by using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, followed by direct DNA sequencing of the PCR-amplified genomic DNA. Subsequently, serum molecular markers were analyzed for their correlation with patients' clinicopathologic features and presence of postoperative recurrence/metastasis. We did not observe any significant difference in the association of APC or K-ras or p53 gene mutations in primary tumors with patients' demographic data (all were P > 0.05). In contrast, both serum APC and p53 molecular markers were closely correlated with lymph node metastasis and TNM stage (both P < 0.05). Moreover, the serum overall molecular markers (at least one of the three markers) were prominently associated with depth of tumor invasion (P = 0.033), lymph node metastasis (P < 0.001), and TNM stage (P < 0.001). In addition, a significantly higher postoperative metastasis/recurrence rate in patients positive for overall molecular markers compared to those negative for these molecular markers were also demonstrated (P < 0.001). APC and K-ras molecular markers were more frequently observed in patients with locoregional metastasis (both P < 0.05), while p53 molecular marker was usually detected in the cases of peritoneal metastasis (P = 0.004). Our findings suggest that serum molecular markers are potentially useful in the determination of colorectal cancer patients harboring gene mutations at high risk of metastasis. Serial analysis is warranted in order to assess their long-term prognostic significance and the therapeutic implications.
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PMID:APC, K-ras, and p53 gene mutations in colorectal cancer patients: correlation to clinicopathologic features and postoperative surveillance. 1594 10

Aberrant crypt foci (ACF), the earliest neoplastic lesions of the colon, have genetic and epigenetic alterations. Loss of heterozygosity (LOH) of tumor suppressor gene loci is seen in most colon cancers, but it is not known how early in tumorigenesis this takes place. Nine microsatellite markers close to specific genes, that is, APC (5q21), PTPRJ (11p11), p53 (17p13) and DCC (18q21), were analyzed in 32 ACF and samples of normal crypts from the same 28 patients. Six losses of heterozygosity were found in 5 of 32 ACF: 4 losses of heterozygosity were at 11p11, the location of the gene for protein tyrosine phosphatase receptor type J (PTPRJ) and of a second independent region of deletion; the others were at 5q21 and 18q21. Microsatellite instability (MSI) with markers for a single locus was found in 4 of 32 ACF. All the observed allelic alterations (LOH and MSI) were in 8 of 32 ACF. The finding of LOH in ACF with normal expressions of adenomatous polyposis coli (APC) and beta-catenin proteins suggests that LOH can occur very early in colon neoplasia and perhaps even before APC mutations. The finding of 3 of 4 of the losses of heterozygosity at 11p11 for PTPRJ and half of all the losses of heterozygosity in this study at PTPRJ suggest that this gene plays a role early in colon neoplasia.
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PMID:Loss of heterozygosity in human aberrant crypt foci (ACF), a putative precursor of colon cancer. 1647 78

Small intestinal adenocarcinoma is an uncommon neoplasm morphologically similar to or indistinguishable from colorectal adenocarcinoma. Although much has been learned about genetic pathways critical to colorectal tumorigenesis, little is known about molecular alterations involved in the development of small intestinal adenocarcinoma. In this study, we immunohistochemically compared non-ampullary small intestinal adenocarcinomas with sporadic colorectal adenocarcinomas for the expression of several proteins known to serve pivotal roles in colorectal tumorigenesis. These included adenomatous polyposis coli and beta-catenin involved in the Wnt signaling pathway, and DNA mismatch repair enzymes hMLH1, hMSH2 and hMSH6 involved in the microsatellite instability pathway. The expression of two important tumor suppressors, p53 and RB, was also examined. The results show that complete loss of adenomatous polyposis coli immunoreactivity, presumably resulting from its gene mutations, was observed in eight of 26 (31%) small intestinal adenocarcinomas and 36 of 51 (71%) colorectal adenocarcinomas (P = 0.0008). Nuclear localization of beta-catenin, an indirect evidence of deregulated Wnt signaling pathway, was observed in 5 (19%) small intestinal adenocarcinomas and 36 (71%) colorectal adenocarcinomas (P<0.0001). Total lack of nuclear staining for one or more of the DNA mismatch repair enzymes occurred in a similar low frequency in both small intestinal and colorectal adenocarcinomas, seen in two of 25 (8%) and 10 of 47 (21%) cases, respectively (P = 0.1958). The frequencies of aberrant p53 and RB expression were also similar between small intestinal and colorectal adenocarcinomas. These observations indicate that defects in the Wnt and microsatellite instability pathways occur in over 90% of colorectal adenocarcinomas, but in only 40% of small intestinal adenocarcinomas. Small intestinal tumorigenesis appears to follow a distinct, yet unidentified, molecular pathway(s) from its colorectal counterpart despite their morphologic similarity.
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PMID:Immunohistochemical investigation of tumorigenic pathways in small intestinal adenocarcinoma: a comparison with colorectal adenocarcinoma. 1650 64

Beta-catenin is a bi-functional protein. It is not only a major component of the cellular adhesion machinery, but is also a transcription co-activator of the Wnt signaling pathway. The cytosolic levels of the beta-catenin protein, as well as its subcellular localization, are tightly regulated due to its oncogenic potentials. Two independent pathways are found to regulate beta-catenin. The canonical pathway is induced by the Axin/adenomatous polyposis coli (APC)/glycogen synthase kinase-3beta (GSK-3beta) complex which is dependent on GSK-3beta phosphorylation. The non-canonical pathway is mediated by p53-induced Siah-1 which is GSK-3beta phosphorylation-independent. Recently, several studies reported that IkappaB kinase alpha (IKKalpha) could stabilize beta-catenin and stimulate beta-catenin/T cell factor (Tcf)-dependent transcription. Here we report that IKKalpha could inhibit beta-catenin degradation mediated not only by the Axin/APC/GSK-3beta complex, but also by the Siah-1 pathway. Consistently, we found that IKKalpha abolished the inhibition of beta-catenin/Tcf-dependent transcription by Siah-1. Furthermore, we found that IKKalpha interacted with beta-catenin and inhibited beta-catenin ubiquitination. Taken together, our results provide a new insight into IKKalpha-mediated beta-catenin stabilization.
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PMID:IKKalpha stabilizes cytosolic beta-catenin by inhibiting both canonical and non-canonical degradation pathways. 1661 28

The etiology and significance of genomic instability (GIN), a hallmark of human cancers, remains controversial. The paradigm that inactivation of tumor suppressors [e.g. p53 or adenomatous polyposis coli (APC) genes] leads to GIN is largely based on experiments in vitro and in animal models. It remains unclear whether GIN is a cause or a result of cancer, particularly in patients. Precancerous Barrett's esophagus (BE) provides a clinical model to investigate GIN in cancer progression. We analyzed specimens from endoscopic biopsies or esophagectomies in patients with BE (ten cases, including five cases with multilayered epithelium (ME)), BE-associated esophageal adenocarcinoma (ten cases), or with normal gastro-esophageal junction (five cases). Chromosomal enumeration probe Cep 7, 11, 12, 17 and 18 were detected by fluorescence in situ hybridization (FISH). Expression of p53 and APC were determined by immunohistochemistry. Increased p53 expression, a measurement of p53 mutations, was observed in BE with high grade dysplasia (HGD) and in BE-associated esophageal cancer (EC). The expression of wild type APC was decreased in BE with HGD and in advanced EC. Chromosomal abnormalities were found in all EC samples. Numeric changes of chromosome 7, 11 and 12 were observed in BE in 14%, 64% and 43% of cases, respectively. Aneusomy of chromosome 11 and 12 were found in ME and in BE without dysplasia, in the presence of normal expression pattern of p53 and APC. Our results suggest that GIN is an early event that occurs at precancerous stages prior to changes in tumor suppressor genes (p53 and APC) in BE-associated tumorigenesis in patients, suggesting that GIN may serve as a causative link between chronic inflammation and cancer.
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PMID:Genomic instability in precancerous lesions before inactivation of tumor suppressors p53 and APC in patients. 1685 98

Previous studies have identified several proteins that associate with microtubules and the dynein motor complex including p53, the glucocorticoid and the vitamin D receptors, and the APC (adenomatous polyposis coli) protein; but neither the residues important for this interaction nor the physical state of the proteins involved have been clarified. We observed in SN12C cells harboring a mutant p53 truncated at amino acid 336, impaired nuclear localization and impaired association with dynein. This finding was confirmed and extended by examining a series of truncated p53 proteins that identified residues 336 to 348 as crucial for association with dynein and nuclear transport. Point mutations identified the importance of residues involved in p53 oligomerization in this process, establishing a p53 oligomer as the cargo for dynein transport. The association of cytosolic p53 oligomers with dynein occurs independent of microtubules indicating that following this association, the p53/dynein complex then associates with microtubules and is transported to the peri-nuclear region. These studies suggest that mutations or modifications that affect p53 oligomerization not only interfere with DNA binding but also with its intracellular distribution. They also highlight the importance of an intact microtubule network in the trafficking of crucial cellular proteins.
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PMID:Oligomerization of p53 precedes its association with dynein and nuclear accumulation. 1696 6

The adenomatous polyposis coli or beta-catenin genes are frequently mutated in colorectal cancer cells, resulting in oncogenic activation of beta-catenin signaling. We tried to establish in vitro and in vivo models for selectively killing human cancer cells with an activated beta-catenin/T-cell factor (Tcf) pathway. We used a recombinant adenovirus that carries a lethal gene [p53-up-regulated modulator of apoptosis (PUMA)] under the control of a beta-catenin/Tcf-responsive promoter (AdTOP-PUMA) to selectively target human colorectal cancer cells (SW480, HCT116, DLD-1, and LS174T), hepatocellular carcinoma (HepG2), and gastric cancer cells (AGS) in which the beta-catenin/Tcf pathway is activated, and compared its efficiency in killing cancer cells in which this pathway is inactive or only weakly active. AdFOP-PUMA, carrying a mutant Tcf-binding site, was used as control virus. The combined effect of AdTOP-PUMA with several chemotherapeutic agents (5-florouracil, doxorubicin, and paclitaxel) was also evaluated. The effect of AdTOP-PUMA on colorectal cancer cells was also examined in nude mice: SW480 cells were infected with the AdTOP-PUMA and AdFOP-PUMA, and then inoculated s.c. into nude mice. The TOP-PUMA adenovirus inhibited cell growth in a dose-dependent fashion, depending on the signaling activity of beta-catenin. The growth of cells displaying high levels of active beta-catenin/Tcf signaling was inhibited after infection with AdTOP-PUMA, whereas that of cells with low levels of beta-catenin signaling was not. Growth inhibition was associated with induction of apoptosis. Chemotherapy synergistically enhanced the effect of AdTOP-PUMA. A combination of the adenovirus system with standard therapy may improve the efficacy and reduce the toxicity of therapy in humans.
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PMID:Targeting the active beta-catenin pathway to treat cancer cells. 1712 33

Although chromosomal instability characterizes the majority of human colorectal cancers, the contribution of genes such as adenomatous polyposis coli (APC), KRAS, and p53 to this form of genetic instability is still under debate. Here, we have assessed chromosomal imbalances in tumors from mouse models of intestinal cancer, namely Apc(+/1638N), Apc(+/1638N)/KRAS(V12G), and Apc(+/1638N)/Tp53-/-, by array comparative genomic hybridization. All intestinal adenomas from Apc(+/1638N) mice displayed chromosomal alterations, thus confirming the presence of a chromosomal instability defect at early stages of the adenoma-carcinoma sequence. Moreover, loss of the Tp53 tumor suppressor gene, but not KRAS oncogenic activation, results in an increase of gains and losses of whole chromosomes in the Apc-mutant genetic background. Comparative analysis of the overall genomic alterations found in mouse intestinal tumors allowed us to identify a subset of loci syntenic with human chromosomal regions (eg, 1p34-p36, 12q24, 9q34, and 22q) frequently gained or lost in familial adenomas and sporadic colorectal cancers. The latter indicate that, during intestinal tumor development, the genetic mechanisms and the underlying functional defects are conserved across species. Hence, our array comparative genomic hybridization analysis of Apc-mutant intestinal tumors allows the definition of minimal aneuploidy regions conserved between mouse and human and likely to encompass rate-limiting genes for intestinal tumor initiation and progression.
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PMID:Aneuploidy arises at early stages of Apc-driven intestinal tumorigenesis and pinpoints conserved chromosomal loci of allelic imbalance between mouse and human. 1720 Feb 9

The beta-catenin signaling pathway is dysregulated in most cases of colon cancer resulting in an accumulation of nuclear beta-catenin and increased transcription of genes involved in tumor progression. This study examines the effect of retinol on beta-catenin protein levels in three all-trans retinoic acid (ATRA)-resistant human colon cancer cell lines: HCT-116, WiDr, and SW620. Each cell line was treated with increasing concentrations of retinol for 24 or 48 h. Retinol reduced beta-catenin protein levels and increased ubiquitinated beta-catenin in all cell lines. Treatment with the proteasomal inhibitor MG132 blocked the retinol-induced decrease in beta-catenin indicating retinol decreases beta-catenin by increasing proteasomal degradation. Multiple pathways direct beta-catenin to the proteasome for degradation including a p53/Siah-1/adenomatous polyposis coli (APC), a Wnt/glycogen synthase kinase-3beta/APC, and a retinoid "X" receptor (RXR)-mediated pathway. Due to mutations in beta-catenin (HCT-116), APC (SW620), and p53 (WiDr), only the RXR-mediated pathway remains functional in each cell line. To determine if RXRs facilitate beta-catenin degradation, cells were treated with the RXR pan-antagonist, PA452, or transfected with RXRalpha small interfering RNA (siRNA). The RXR pan-antagonist and RXRalpha siRNA reduced the ability of retinol to decrease beta-catenin protein levels. Nuclear beta-catenin induces gene transcription via interaction with T cell factor/lymphoid enhancer factor (TCF/LEF) proteins. Retinol treatment decreased the transcription of a TOPFlash reporter construct and mRNA levels of the endogenous beta-catenin target genes, cyclin D1 and c-myc. These results indicate that retinol may reduce colon cancer cell growth by increasing the proteasomal degradation of beta-catenin via a mechanism potentially involving RXR.
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PMID:Retinol decreases beta-catenin protein levels in retinoic acid-resistant colon cancer cell lines. 1721 22

This study was done to characterize base excision repair (BER) genes and adenomatous polyposis coli (APC) alterations in the tumorigenesis of multiple colorectal adenomas in Korean patients. In total, 217 adenomas (mean number = 10) and 117 cancers were available from 143 patients. The heterozygous genotype of OGG1 c.1-18G>T was closely associated with multiple adenoma families (P < 0.001), while MYH A359V mutation exhibited a tendency (P = 0.053). MYH R170G mutation was exclusively identified in one patient. The G:C>T:A transversion or attenuated familial adenomatous polyposis (AFAP) mutations of APC was identified in the specific genotypes of BER variants. Tubular adenomas or adenomas with none-to-mild dysplasia were significantly associated with polymorphic genotypes of OGG1 IVS4-15 and S326C. In addition, large and pedunculated adenomas were more frequent in patients with G:C>T:A transversion and AFAP mutations of APC, respectively. However, BER variants were not associated with mismatch repair or altered p53 protein expression. Conclusively, two novel mutations of MYH and a novel OGG1 polymorphism seemed to be associated with multiple colorectal adenomas in Korean families, differing from those in other ethnic groups. Some BER variants involved in specific APC mutations are associated with characteristics of histogenesis other than altered mismatch repair or p53 pathway.
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PMID:MYH, OGG1, MTH1, and APC alterations involved in the colorectal tumorigenesis of Korean patients with multiple adenomas. 1725 31


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