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1.
Catenins, Wnt signaling and cancer   总被引:35,自引:0,他引:35  
Recent studies indicate that plakoglobin may have a similar function to that of beta-catenin within the Wnt signaling pathway. beta-catenin is known to be an oncogene in many forms of human cancer, following acquisition of stabilizing mutations in amino terminal sequences. Kolligs(1) and coworkers show, however, that unlike beta-catenin, plakoglobin induces neoplastic transformation of rat epithelial cells in the absence of such stabilizing mutations. Cellular transformation by plakoglobin also appears to be distinct from that of beta-catenin in that it requires activation of the proto-oncogene c-myc. Surprisingly, c-myc is activated more efficiently by plakoglobin than beta-catenin, despite its previous identification as a target of Tcf/beta-catenin.(2) In contrast, a synthetic Tcf reporter gene is activated to a much greater extent by beta-catenin than plakoglobin. Plakoglobin and beta-catenin may therefore have different roles in Wnt signaling and cancer, which reflect their differential effects on target gene activity.  相似文献   

2.
The ADAM and ADAMTS families, also called adamalysins belong to an important group of extracellular matrix proteins. The ADAMs family belong to both the transmembrane and secreted proteins, while ADAMTS family only contains secreted forms. Adamalysins play an important role in the cell phenotype regulation via their activities in signaling pathways, cell adhesion and migration. The human proteome contains 21 ADAM, and 19 ADAMTS proteins, which are involved in extracellular matrix remodeling, shedding of various substrates such as: adhesion ligands, growth factors, their receptors and diverse cytokines. Recent studies provide evidence that adamalysins play a crucial role in colorectal cancer (CRC) etiopathogenesis. It seems possible that adamalysins might be used as CRC prediction markers or potential pharmaceutical targets. [BMB Reports 2013; 46(3): 139-150]  相似文献   

3.
Ribosomal proteins and colorectal cancer   总被引:1,自引:0,他引:1  
Lai MD  Xu J 《Current Genomics》2007,8(1):43-49
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4.
Catenins: keeping cells from getting their signals crossed   总被引:8,自引:0,他引:8  
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5.
6.
Kim YK  Heo I  Kim VN 《Cell》2010,143(5):703-709
Small regulatory RNAs and their associated proteins are subject to diverse modifications that can impinge on their abundance and function. Some of the modifications are under the influence of cellular signaling, thus contributing to the dynamic regulation of RNA silencing.  相似文献   

7.
Mass spectrometry-based serum metabolic profiling is a promising tool to analyse complex cancer associated metabolic alterations, which may broaden our pathophysiological understanding of the disease and may function as a source of new cancer-associated biomarkers. Highly standardized serum samples of patients suffering from colon cancer (n?=?59) and controls (n?=?58) were collected at the University Hospital Leipzig. We based our investigations on amino acid screening profiles using electrospray tandem-mass spectrometry. Metabolic profiles were evaluated using the Analyst 1.4.2 software. General, comparative and equivalence statistics were performed by R 2.12.2. 11 out of 26 serum amino acid concentrations were significantly different between colorectal cancer patients and healthy controls. We found a model including CEA, glycine, and tyrosine as best discriminating and superior to CEA alone with an AUROC of 0.878 (95% CI 0.815-0.941). Our serum metabolic profiling in colon cancer revealed multiple significant disease-associated alterations in the amino acid profile with promising diagnostic power. Further large-scale studies are necessary to elucidate the potential of our model also to discriminate between cancer and potential differential diagnoses. In conclusion, serum glycine and tyrosine in combination with CEA are superior to CEA for the discrimination between colorectal cancer patients and controls.  相似文献   

8.
The purpose of this article is to summarize the role of gamma probes in intraoperative tumor detection in patients with colorectal cancer (CRC), as well as provide basic information about the physical and practical characteristics of the gamma probes, and the radiopharmaceuticals used in gamma probe tumor detection. In a significant portion of these studies, radiolabeled monoclonal antibodies (Mabs), particularly 125I labeled B72.3 Mab that binds to the TAG-72 antigen, have been used to target tumor. Studies have reported that intraoperative gamma probe radioimmunodetection helps surgeons to localize primary tumor, clearly delineate its resection margins and provide immediate intraoperative staging. Studies also have emphasized the value of intraoperative gamma probe radioimmunodetection in defining the extent of tumor recurrence and finding sub-clinical occult tumors which would assure the surgeons that they have completely removed the tumor burden. However, intraoperative gamma probe radioimmunodetection has not been widely adapted among surgeons because of some constraints associated with this technique. The main difficulty with this technique is the long period of waiting time between Mab injection and surgery. The technique is also laborious and costly. In recent years, Fluorine-18-2-fluoro-2-deoxy-D-glucose (18F-FDG) use in gamma probe tumor detection surgery has renewed interest among surgeons. Preliminary studies during surgery have demonstrated that use of FDG in gamma probe tumor detection during surgery is feasible and useful.  相似文献   

9.
Missense mutations in hMLH1 associated with colorectal cancer   总被引:3,自引:0,他引:3  
One of the most prevalent hereditary syndromes associated with colorectal cancer is hereditary nonpolyposis colorectal cancer (HNPCC). The inherited gene defects in HNPCC have been shown to reside in DNA mismatch repair genes, mostly hMSH2 or hMLH1. Most HNPCC patients are heterozygous with regard to the relevant mismatch repair gene; they have one normal and one mutated allele, and mismatch repair in normal somatic cells is functional. Cancer predisposition in HNPCC is believed to be associated with the loss of the wild-type allele in somatic cells, resulting in defective DNA mismatch repair. This gives rise to DNA microsatellite instability (MSI), an increased somatic mutation rate, and eventually, to the accumulation of mutations in genes involved in colorectal carcinogenesis. In support of this theory, colorectal tumors in HNPCC patients and in mice deficient for hMSH2 or hMLH1 show MSI. Here, we describe two missense mutations in hMLH1 exon 16 associated with colorectal cancer. Interestingly, the tumors do not show MSI. This raises some potentially important issues. First, even microsatellite-negative colorectal tumors can be associated with germline mutations and these will be missed if an MSI test is used to select patients for mutation screening. Second, the lack of MSI in these cases suggests that the mechanism involved in carcinogenesis could be different from that generally hypothesized.  相似文献   

10.
Here, we describe a proteomics approach to study protein expression changes in differentiating Caco-2 cells. Caco-2 is a colorectal carcinoma cell line, which upon differentiation loses its tumorigenic phenotype and displays characteristics of mature enterocytes, including brush borders with microvilli. Cells were grown in culture flasks and harvested at different stages of differentiation (days post-confluence: -3, 0, 3, 7, 10, 14, and 18). Two-dimensional gel electrophoresis was used to analyse proteome changes. Approximately 1400 protein spots were detected within the Caco-2 proteome, within the pH 4-7 range. Two-dimensional gel electrophoresis allowed for the detection of 18 proteins from which the levels of expression were found to be associated with differentiation. Of these proteins, 11 were identified by means of MALDI-TOF or NANO-ESI-MS/MS mass spectrometry and include liver fatty acid binding protein (FABL), three forms of alpha-enolase (ENOA), nucleoside diphosphate kinase A (NDKA), cofilin-1 (COF1), translationally controlled tumour protein (TCTP), mitochondrial 60-kDa heat shock protein (CH60), probable protein disulfide isomerase (ER60), creatine kinase B (KCRB), and glutathione S-transferase alpha (GTA1). Thus, proteomics revealed that the differentiation-related change in phenotype of Caco-2 involves changes in a variety of distinct biochemical pathways. Some of these proteins have not been shown before to be associated with Caco-2 differentiation (ER60; COF1; CH60; NDKA; TCTP and ENOA). Therefore, processes related to protein folding and disulfide bridge formation, cytoskeleton formation and maintenance, nucleotide metabolism, glycolysis as well as tumorigenesis-associated proteins may be involved in Caco-2 differentiation. Changes in the expression of CH60, TCTP, GTA1, NDKA, and FABL have also been reported to be associated with in vivo colon carcinogenesis. These findings illustrate that a combination of proteomics and cell culture is a useful approach to find markers for Caco-2 differentiation, which could contribute to the comprehension of the process of colon carcinogenesis.  相似文献   

11.
Bone morphogenetic proteins (BMPs) belong to the TGF-Beta superfamily and are vital bone inductive factors. BMPs also play important roles during embryonic development and the postnatal homeostasis of various organs and tissues, by controlling cellular differentiation, proliferation and apoptosis. Prostate cancer is the most common cancer in men in Western countries, with a high incidence of bone metastasis. Once bony metastasis developed, the condition is incurable, and contributes significant disease specific morbidity and mortality. However, the mechanisms underlying the development of bone metastasis remain unclear. BMPs have been implicated in the development of both primary and secondary tumors, particularly skeletal metastasis. Aberrations in BMPs signaling have also been identified in various neoplasms. Recently studies have also suggested a pivotal role in bone metastasis for Noggin, which is a BMP antagonist. In this review, we discuss the current knowledge of BMPs signaling, abnormalities which have been identified and their involvement in tumour progression, and particularly in the development of bone metastasis in prostate cancer.  相似文献   

12.
Chemoresistance is a major therapeutic obstacle in cancer patients, and the mechanisms of drug resistance are not fully understood. In the present study, we established platinum-resistant human ovarian cancer cell lines and identified differentially expressed proteins related to platinum resistance. The total proteins of two sensitive (SKOV3 and A2780) and four resistant (SKOV3/CDDP, SKOV3/CBP, A2780/CDDP, and A2780/CBP) human ovarian cancer cell lines were isolated by two-dimensional gel electrophoresis (2-DE). The differentially expressed proteins were identified using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). In total, 57 differential protein spots were identified, and five proteins, including annexin A3, destrin, cofilin 1, Glutathione-S-transferase omega 1 (GSTO1-1), and cytosolic NADP+-dependent isocitrate dehydrogenase (IDHc), were found to be co-instantaneous significance compared with their parental cells. The expression of the five proteins was validated by quantitative PCR and western blot, and the western blot results showed complete consistency with proteomic techniques. The five proteins are hopeful to become candidates for platinum resistance. These may be useful for further study of resistance mechanisms and screening of resistant biomarkers.  相似文献   

13.
14.
Kostenis E  Zeng FY  Wess J 《Life sciences》1999,64(6-7):355-362
Each member of the muscarinic receptor family (M1-M5) can interact only with a limited subset of the many structurally closely related heterotrimeric G proteins expressed within a cell. To understand how this selectivity is achieved at a molecular level, we have used the G(i/0)-coupled M2 and the Gq/11-coupled M3 muscarinic receptors as model systems. We developed a genetic strategy involving the coexpression of wild type or mutant muscarinic receptors with hybrid or mutant G protein alpha subunits to identify specific, functionally relevant receptor/G protein contact sites. This approach led to the identification of N- and C-terminal amino acids on alpha(q) and alpha(i) that are critical for maintaining proper receptor/G protein coupling. Moreover, several receptor sites were identified that are likely to be contacted by these functionally critical G alpha residues. To gain deeper insight into muscarinic receptor structure, we recently developed a cysteine disulfide cross-linking strategy, using the M3 muscarinic receptor as a model system. Among other structural modifications, this approach involves the removal of most native cysteine residues by site-directed mutagenesis, the insertion of three factor Xa cleavage sites into the third intracellular loop, and systematic 'reintroduction' of pairs of cysteine residues. Following treatment of receptor-containing membrane preparations with factor Xa and oxidizing agents, disulfide cross-linked products can be identified by immunoprecipitation and immunoblotting studies. This approach should greatly advance our knowledge of the molecular architecture of muscarinic and other G protein-coupled receptors.  相似文献   

15.
This paper analyzes the DNA code of several species in the perspective of information content. For that purpose several concepts and mathematical tools are selected towards establishing a quantitative method without a priori distorting the alphabet represented by the sequence of DNA bases. The synergies of associating Gray code, histogram characterization and multidimensional scaling visualization lead to a collection of plots with a categorical representation of species and chromosomes.  相似文献   

16.
The tumor suppressor TP53 gene is one of the most frequently mutated in different types of human cancer. Particularly in colorectal cancer (CRC), it is believed that TP53 mutations play a role in the adenoma–carcinoma transition of tumors during pathological process. In order to analyze TP53 expressed alleles in CRC, we examined TP53 mRNA in tumor samples from 101 patients with sporadic CRC. Samples were divided in two groups defined according to whether they exhibit positive or negative P53 protein expression as detected by immunohistochemistry (IHC). The presence of TP53 mutation was a common event in tumors with an overall frequency of 54.5%. By direct sequencing, we report 42 different TP53 sequence changes in 55 CRC patients, being two of them validated polymorphisms. TP53 mutations were more frequent in positive than in negative P53 detection group (p < 0.0001), being the precise figures 79.6% and 30.8%, respectively. In addition, the mutation profiles were also different between the two groups of samples; while most of the mutations detected in P53 positive group were missense (38 out of 39), changes in P53 negative detection group include 7 insertions/deletions, 6 missense, 2 nonsense and 1 silent mutation. As previously observed, most mutations were concentrated in regions encoding P53 DNA binding domain (DBD). Codons 175, 248 and 273 together account for 36.7% of point mutations, in agreement with previous observations provided that these codons are considered mutation hotspots. Interestingly, we detected two new deletions and two new insertions. In addition, in three samples we detected two deletions and one insertion that could be explained as putative splicing variants or splicing errors.  相似文献   

17.
18.
Experimental evidence directly implicates complex carbohydrates in recognition processes, including adhesion between cells, adhesion of cells to the extracellular matrix, and specific recognition of cells by one another. In addition, carbohydrates are recognized as differentiation markers and as antigenic determinants. Lectins are nonenzymatic proteins present in plants and animals, which preferentially bind to specific carbohydrate structures and play an important role in cell recognition. Modified carbohydrates and oligosaccharides have the ability to interfere with carbohydrate-protein interactions and therefore, inhibit the cell-cell recognition and adhesion processes, which play an important role in cancer growth and progression. Carbohydrate ligands therefore, are candidates to play important roles in cancer therapeutics.  相似文献   

19.
Tumors are comprised of malignant cancer cells and stromal cells which constitute the tumor microenvironment (TME). Previous studies have shown that cancer associated fibroblast (CAF) in TME is an important promoter of tumor initiation and progression. However, the underlying molecular mechanisms by which CAFs influence the growth of colorectal cancer cells (CRCs) have not been clearly elucidated. In this study, by using a non-contact co-culture system between human colorectal fibroblasts (CCD-18-co) and CRCs (LoVo, SW480, and SW620), we found that fibroblasts existing in tumor microenvironment positively influenced the metabolism of colorectal cancer cells, through its autophagy and oxidative stress pathway which were initially induced by neighboring tumor cells. Therefore, our data provided a novel possibility to develop fibroblasts as a potential target to treat CRC.  相似文献   

20.
Classical cadherins mediate specific adhesion at intercellular adherens junctions. Interactions between cadherin ectodomains from apposed cells mediate cell–cell contact, whereas the intracellular region functionally links cadherins to the underlying cytoskeleton. Structural, biophysical, and biochemical studies have provided important insights into the mechanism and specificity of cell–cell adhesion by classical cadherins and their interplay with the cytoskeleton. Adhesive binding arises through exchange of β strands between the first extracellular cadherin domains (EC1) of partner cadherins from adjacent cells. This “strand-swap” binding mode is common to classical and desmosomal cadherins, but sequence alignments suggest that other cadherins will bind differently. The intracellular region of classical cadherins binds to p120 and β-catenin, and β-catenin binds to the F-actin binding protein α-catenin. Rather than stably bridging β-catenin to actin, it appears that α-catenin actively regulates the actin cytoskeleton at cadherin-based cell–cell contacts.Cadherins constitute a large family of cell surface proteins, many of which participate in Ca2+-dependent cell adhesion that plays a fundamental role in the formation of solid tissues (Takeichi 1995; Tepass 1999; Gumbiner 2005). Many events in the development of multicellular assemblies are associated with changes in cadherin expression (Takeichi 1995; Honjo et al. 2000; Price et al. 2002). Expression of particular cadherins often correlates with formation of discrete tissue structures, and in mature tissues discrete cell layers or other cell assemblies are often demarcated by particular cadherins (Gumbiner 1996). Conversely, down-regulation or loss of cadherins correlates with an increased metastatic potential of the affected cells that arises from the loss of their adhesive properties (Hajra and Fearon 2002; Gumbiner 2005).The cadherins of vertebrates, and some of their invertebrate homologs, are the most highly characterized. “Classical” cadherins, associated with the adherens junction, and the closely related desmosomal cadherins feature an amino-terminal extracellular region or ectodomain that is followed by a transmembrane anchor and a carboxy-terminal intracellular region. Interactions between ectodomains on apposed cells mediate specific cell–cell contacts, whereas the intracellular region functionally links cadherins to the underlying cytoskeleton. This article focuses on structural, biophysical, and biochemical studies that have provided important mechanistic insights into the specificity of cell–cell adhesion and its interplay with the cytoskeleton (see also Meng and Takeichi 2009; Cavey and Lecuit 2009).  相似文献   

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