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Stephen P. Pereira - One of the best experts on this subject based on the ideXlab platform.
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Diagnosis of pancreaticobiliary malignancy by detection of Minichromosome Maintenance protein 5 in biliary brush cytology
British Journal of Cancer, 2017Co-Authors: M G Keane, Matthew T Huggett, D Thorburn, Michael H. Chapman, Gavin J. Johnson, J Mackay, George J Webster, Stephen P. PereiraAbstract:Background: Biliary brush cytology is the standard method of evaluating biliary strictures, but is insensitive at detecting malignancy. In pancreaticobiliary cancer Minichromosome Maintenance replication proteins (MCM 2–7) are dysregulated in the biliary epithelium and MCM5 levels are elevated in bile samples. This study aimed to validate an immunocolorimetric ELISA assay for MCM5 as a pancreaticobiliary cancer biomarker in biliary brush samples. Methods: Biliary brush specimens were collected prospectively at ERCP from patients with a biliary stricture. Collected samples were frozen at −80 °C. The supernatant was washed and lysed cells incubated with HRP-labelled anti-MCM5 mouse monoclonal antibody. Test positivity was determined by optical density absorbance. Patients underwent biliary brush cytology or additional investigations as per clinical routine. Results: Ninety-seven patients were included in the study; 50 had malignant strictures. Median age was 65 years (range 21–94) and 51 were male. Compared with final diagnosis the MCM5 assay had a sensitivity for malignancy of 65.4% compared with 25.0% for cytology. In the 72 patients with paired MCM5 assay and biliary brush cytology, MCM5 demonstrated an improved sensitivity (55.6% vs 25.0%; P =0.0002) for the detection of malignancy. Conclusions: Minichromosome Maintenance replication protein5 is a more sensitive indicator of pancreaticobiliary malignancy than standard biliary brush cytology.
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diagnosis of pancreaticobiliary malignancy by detection of Minichromosome Maintenance protein 5 in biliary brush cytology
British Journal of Cancer, 2017Co-Authors: M G Keane, Matthew T Huggett, D Thorburn, Michael H. Chapman, Gavin J. Johnson, George Webster, Stephen P. Pereira, J MackayAbstract:Diagnosis of pancreaticobiliary malignancy by detection of Minichromosome Maintenance protein 5 in biliary brush cytology
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diagnosis of pancreaticobiliary malignancy by detection of Minichromosome Maintenance protein 5 in biliary brush cytology
British Journal of Cancer, 2017Co-Authors: M G Keane, Matthew T Huggett, D Thorburn, Michael H. Chapman, George Webster, Stephen P. Pereira, J Mackay, Gavin JohnsonAbstract:Biliary brush cytology is the standard method of evaluating biliary strictures, but is insensitive at detecting malignancy. In pancreaticobiliary cancer Minichromosome Maintenance replication proteins (MCM 2–7) are dysregulated in the biliary epithelium and MCM5 levels are elevated in bile samples. This study aimed to validate an immunocolorimetric ELISA assay for MCM5 as a pancreaticobiliary cancer biomarker in biliary brush samples. Biliary brush specimens were collected prospectively at ERCP from patients with a biliary stricture. Collected samples were frozen at −80 °C. The supernatant was washed and lysed cells incubated with HRP-labelled anti-MCM5 mouse monoclonal antibody. Test positivity was determined by optical density absorbance. Patients underwent biliary brush cytology or additional investigations as per clinical routine. Ninety-seven patients were included in the study; 50 had malignant strictures. Median age was 65 years (range 21–94) and 51 were male. Compared with final diagnosis the MCM5 assay had a sensitivity for malignancy of 65.4% compared with 25.0% for cytology. In the 72 patients with paired MCM5 assay and biliary brush cytology, MCM5 demonstrated an improved sensitivity (55.6% vs 25.0%; P=0.0002) for the detection of malignancy. Minichromosome Maintenance replication protein5 is a more sensitive indicator of pancreaticobiliary malignancy than standard biliary brush cytology.
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diagnosis of pancreaticobiliary malignancy by detection of Minichromosome Maintenance protein 5 in bile aspirates
British Journal of Cancer, 2008Co-Authors: Lakshmana Ayaru, O Okoturo, George Webster, A Wollenschlaeger, Stephen P. Pereira, Kai Stoeber, Arw Hatfield, Mohammed Rashid, Gareth R WilliamsAbstract:Biliary brush cytology is the standard method of sampling a biliary stricture but has a low sensitivity for the detection of malignancy. We have previously shown that Minichromosome Maintenance (MCM) replication proteins (Mcm2–7) are markers of dysplasia and have utilised these novel biomarkers of growth for the diagnosis of cervical and bladder cancer. We aimed to determine if MCM proteins are dysregulated in malignant pancreaticobiliary disease and if levels in bile are a sensitive marker of malignancy. In 30 tissue specimens from patients with malignant/benign biliary strictures, we studied Mcm2 and -5 expression by immunohistochemistry. Bile samples were also collected prospectively at endoscopic retrograde cholangiopancreatography from 102 consecutive patients with biliary strictures of established (n=42) or indeterminate aetiology (n=60). Patients with indeterminate strictures also underwent brush cytology as part of standard practice. Bile sediment Mcm5 levels were analysed using an automated immunofluorometric assay. In benign biliary strictures, Mcm2 and -5 protein expression was confined to the basal epithelial proliferative compartment – in contrast to malignant strictures where expression was seen in all tissue layers. The percentage of nuclei positive for Mcm2 was higher in malignant tissue (median 76.5%, range 42–92%) than in benign tissue (median 5%, range 0–33%) (P<0.0005), with similar results for Mcm5. Minichromosome Maintenance protein 5 levels in bile were significantly more sensitive than brush cytology (66 vs 20%; P=0.004) for the detection of malignancy in patients with an indeterminate stricture, with a comparable positive predictive value (97 vs 100%; P=ns). In this study, we demonstrate that Mcm5 in bile detected by a simple automated test is a more sensitive indicator of pancreaticobiliary malignancy than routine brush cytology.
Okay Saydam - One of the best experts on this subject based on the ideXlab platform.
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Overexpression of Minichromosome Maintenance protein 10 in medulloblastoma and its clinical implications
Pediatric blood & cancer, 2017Co-Authors: Daniel Senfter, Sibylle Madlener, Nurten Saydam, Erdogan Pekcan Erkan, Thomas Strobel, Erdener Özer, Gerhard Jungwirth, Marcel Kool, Okay SaydamAbstract:Background Overexpression of Minichromosome Maintenance (MCM) proteins 2, 3, and 7 is associated with migration and invasion in medulloblastoma (MB). However, expression profiling of all prereplication complex (pre-RC) has not been addressed in MBs. Procedure We performed mRNA expression profiling of a large set of pre-RC elements in cell lines and tumor tissues of MB. RNAi technology was employed for functional studies in MB cell lines. Results Our data showed that most of the pre-RC components are significantly overexpressed in MB. Among all pre-RC mRNAs, MCM10 showed the highest level of expression (∼500- to 1,000-fold) in MB cell lines and tissues compared to the levels detected in cerebellum. In addition, RNAi silencing of MCM10 caused reduced cell proliferation and cell viability in MB cells. Conclusions Taken together, our study reveals that the pre-RC is dysregulated in MB. In addition, MCM10, a member of this complex, is significantly overexpressed in MB and is required for tumor cell proliferation.
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depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
Oncogene, 2014Co-Authors: Erdogan Pekcan Erkan, Grant Lewandrowski, Sibylle Madlener, Nurten Saydam, Thomas Czech, Thomas Strobel, Bakhos A Tannous, Okay SaydamAbstract:Depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
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Depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
Oncogene, 2014Co-Authors: Erdogan Pekcan Erkan, Grant Lewandrowski, Sibylle Madlener, Nurten Saydam, Thomas Czech, Thomas Strobel, B Tannous, Okay SaydamAbstract:Minichromosome Maintenance (MCM) proteins are key elements that function as a part of the pre-replication complex to initiate DNA replication in eukaryotes. Consistent with their roles in initiating DNA replication, overexpression of MCM family members has been observed in several malignancies. Through bioinformatic analysis of The Cancer Genome Atlas’s data on glioblastoma multiforme (GBM), we found that the genomic region containing MCM7 gene was amplified in more than 80% of the present cases. To validate this finding and to identify the possible contribution of the remaining members of the MCM family to GBM progression, we used quantitative real-time PCR to analyze the gene expression profiles of all MCM family members in Grade IV (GBM) tissue samples and observed a significant upregulation in GBM samples compared with normal white matter tissues. In addition, we compared the observed gene expression profiles with those of Grade II and Grade III astrocytoma samples and determined that the observed upregulation was restricted and specific to Grade IV. MCM7 was the most upregulated gene in the gene set we analyzed, and therefore we wanted to identify the role of MCM7 in GBM progression. We determined that siRNA-mediated knockdown of MCM7 expression reduced GBM cell proliferation and also inhibited tumor growth in both xenograft and orthotopic mouse models of GBM. Taken together, our data suggest that MCM7 can be a potential prognostic marker and a novel therapeutic target in GBM therapy.
Erdogan Pekcan Erkan - One of the best experts on this subject based on the ideXlab platform.
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Overexpression of Minichromosome Maintenance protein 10 in medulloblastoma and its clinical implications
Pediatric blood & cancer, 2017Co-Authors: Daniel Senfter, Sibylle Madlener, Nurten Saydam, Erdogan Pekcan Erkan, Thomas Strobel, Erdener Özer, Gerhard Jungwirth, Marcel Kool, Okay SaydamAbstract:Background Overexpression of Minichromosome Maintenance (MCM) proteins 2, 3, and 7 is associated with migration and invasion in medulloblastoma (MB). However, expression profiling of all prereplication complex (pre-RC) has not been addressed in MBs. Procedure We performed mRNA expression profiling of a large set of pre-RC elements in cell lines and tumor tissues of MB. RNAi technology was employed for functional studies in MB cell lines. Results Our data showed that most of the pre-RC components are significantly overexpressed in MB. Among all pre-RC mRNAs, MCM10 showed the highest level of expression (∼500- to 1,000-fold) in MB cell lines and tissues compared to the levels detected in cerebellum. In addition, RNAi silencing of MCM10 caused reduced cell proliferation and cell viability in MB cells. Conclusions Taken together, our study reveals that the pre-RC is dysregulated in MB. In addition, MCM10, a member of this complex, is significantly overexpressed in MB and is required for tumor cell proliferation.
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depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
Oncogene, 2014Co-Authors: Erdogan Pekcan Erkan, Grant Lewandrowski, Sibylle Madlener, Nurten Saydam, Thomas Czech, Thomas Strobel, Bakhos A Tannous, Okay SaydamAbstract:Depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
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Depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
Oncogene, 2014Co-Authors: Erdogan Pekcan Erkan, Grant Lewandrowski, Sibylle Madlener, Nurten Saydam, Thomas Czech, Thomas Strobel, B Tannous, Okay SaydamAbstract:Minichromosome Maintenance (MCM) proteins are key elements that function as a part of the pre-replication complex to initiate DNA replication in eukaryotes. Consistent with their roles in initiating DNA replication, overexpression of MCM family members has been observed in several malignancies. Through bioinformatic analysis of The Cancer Genome Atlas’s data on glioblastoma multiforme (GBM), we found that the genomic region containing MCM7 gene was amplified in more than 80% of the present cases. To validate this finding and to identify the possible contribution of the remaining members of the MCM family to GBM progression, we used quantitative real-time PCR to analyze the gene expression profiles of all MCM family members in Grade IV (GBM) tissue samples and observed a significant upregulation in GBM samples compared with normal white matter tissues. In addition, we compared the observed gene expression profiles with those of Grade II and Grade III astrocytoma samples and determined that the observed upregulation was restricted and specific to Grade IV. MCM7 was the most upregulated gene in the gene set we analyzed, and therefore we wanted to identify the role of MCM7 in GBM progression. We determined that siRNA-mediated knockdown of MCM7 expression reduced GBM cell proliferation and also inhibited tumor growth in both xenograft and orthotopic mouse models of GBM. Taken together, our data suggest that MCM7 can be a potential prognostic marker and a novel therapeutic target in GBM therapy.
Zvi Kelman - One of the best experts on this subject based on the ideXlab platform.
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the methanothermobacter thermautotrophicus cdc6 2 protein the putative helicase loader dissociates the Minichromosome Maintenance helicase
Journal of Bacteriology, 2008Co-Authors: Jaeho Shin, Zvi KelmanAbstract:The Cdc6-1 and -2 proteins from the archaeon Methanothermobacter thermautotrophicus were previously shown to bind the Minichromosome Maintenance (MCM) helicase. It is shown here that Cdc6-2 protein dissociates the MCM complex. This observation supports the hypothesis that the Cdc6-2 protein functions as a helicase loader.
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dna binding by the methanothermobacter thermautotrophicus cdc6 protein is inhibited by the Minichromosome Maintenance helicase
Journal of Bacteriology, 2006Co-Authors: Rajesh Kasiviswanathan, Jaeho Shin, Zvi KelmanAbstract:The Cdc6 proteins from the archaeon Methanothermobacter thermautotrophicus were previously shown to bind double-stranded DNA. It is shown here that the proteins also bind single-stranded DNA. Using Minichromosome Maintenance (MCM) helicase mutant proteins unable to bind DNA, it was found that the interaction of MCM with Cdc6 inhibits the DNA binding activity of Cdc6.
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biochemical characterization of the methanothermobacter thermautotrophicus Minichromosome Maintenance mcm helicase n terminal domains
Journal of Biological Chemistry, 2004Co-Authors: Rajesh Kasiviswanathan, Eugene Melamud, Jaeho Shin, Zvi KelmanAbstract:Abstract Minichromosome Maintenance helicases are ring-shaped complexes that play an essential role in archaeal and eukaryal DNA replication by separating the two strands of chromosomal DNA to provide the single-stranded substrate for the replicative polymerases. For the archaeal protein it was shown that the N-terminal portion of the protein, which is composed of domains A, B, and C, is involved in multimer formation and single-stranded DNA binding and may also play a role in regulating the helicase activity. Here, a detailed biochemical characterization of the N-terminal region of the Methanothermobacter thermautotrophicus Minichromosome Maintenance helicase is described. Using biochemical and biophysical analyses it is shown that domain C of the N-terminal portion, located adjacent to the helicase catalytic domains, is required for protein multimerization and that domain B is the main contact region with single-stranded DNA. It is also shown that although oligomerization is not essential for single-stranded DNA binding and ATPase activity, the presence of domain C is essential for helicase activity.
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substrate requirements for duplex dna translocation by the eukaryal and archaeal Minichromosome Maintenance helicases
Journal of Biological Chemistry, 2003Co-Authors: Jaeho Shin, Beatrice Grabowski, Yun Jiang, Jerard Hurwitz, Zvi KelmanAbstract:Abstract Replicative DNA helicases are ring-shaped hexamers that play an essential role in DNA synthesis by separating the two strands of chromosomal DNA to provide the single-stranded (ss) substrate for replicative polymerases. Biochemical and structural studies suggest that these helicases translocate along one strand of the duplex, which passes through and interacts with the central channel of these ring-shaped hexamers, and displace the complementary strand. A number of these helicases were shown to also encircle both strands simultaneously and then translocate along double-stranded (ds)DNA. In this report it is shown that the Schizosaccharomyces pombe Mcm4,6,7 complex and archaeal Minichromosome Maintenance (MCM) helicase from Methanothermobacter thermautotrophicus move along duplex DNA. These two helicases, however, differ in the substrate required to support dsDNA translocation. Although the S. pombe Mcm4,6,7 complex required a 3′-overhang ssDNA region to initiate its association with the duplex, the archaeal protein initiated its transit along dsDNA in the absence of a 3′-overhang region, as well. Furthermore, DNA substrates containing a streptavidin-biotin steric block inhibited the movement of the eukaryotic helicase along ss and dsDNAs but not of the archaeal enzyme. The M. thermautotrophicus MCM helicase, however, was shown to displace a streptavidin-biotin complex from ss, as well as dsDNAs. The possible roles of dsDNA translocation by the MCM proteins during the initiation and elongation phases of chromosomal replication are discussed.
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Regulation of Minichromosome Maintenance Helicase Activity by Cdc6
Journal of Biological Chemistry, 2003Co-Authors: Jaeho Shin, Beatrice Grabowski, Rajesh Kasiviswanathan, Stephen D. Bell, Zvi KelmanAbstract:Abstract Genetic studies, together with amino acid and structural similarities to the clamp loaders of DNA polymerase sliding clamps, have suggested that the Cdc6 protein may function as a loader for the eukaryotic replicative helicase, the Minichromosome Maintenance (MCM) complex. Thus, Cdc6 may act as the functional homologue of the bacterial DnaC that utilizes ATP hydrolysis to assemble the DnaB helicase at the origin. This report shows that the helicase activity of an MCM homologue from the archaeon Methanothermobacter thermautotrophicus is inhibited in the presence of the Cdc6 homologues. This inhibitory activity is dependent, as for DnaC, on ATP binding to Cdc6. Moreover, an intact Cdc6 winged helix domain is required for efficient inhibition. Two-hybrid analyses indicated that MCM and Cdc6 interact and that the interaction is mediated by the winged helix domain. Analysis of Cdc6 and MCM homologues from several archaea exhibited differences in the inhibitory activity suggesting divergence in function in Cdc6 and MCM homologues among the archaea.
Grant Lewandrowski - One of the best experts on this subject based on the ideXlab platform.
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depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
Oncogene, 2014Co-Authors: Erdogan Pekcan Erkan, Grant Lewandrowski, Sibylle Madlener, Nurten Saydam, Thomas Czech, Thomas Strobel, Bakhos A Tannous, Okay SaydamAbstract:Depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
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Depletion of Minichromosome Maintenance protein 7 inhibits glioblastoma multiforme tumor growth in vivo
Oncogene, 2014Co-Authors: Erdogan Pekcan Erkan, Grant Lewandrowski, Sibylle Madlener, Nurten Saydam, Thomas Czech, Thomas Strobel, B Tannous, Okay SaydamAbstract:Minichromosome Maintenance (MCM) proteins are key elements that function as a part of the pre-replication complex to initiate DNA replication in eukaryotes. Consistent with their roles in initiating DNA replication, overexpression of MCM family members has been observed in several malignancies. Through bioinformatic analysis of The Cancer Genome Atlas’s data on glioblastoma multiforme (GBM), we found that the genomic region containing MCM7 gene was amplified in more than 80% of the present cases. To validate this finding and to identify the possible contribution of the remaining members of the MCM family to GBM progression, we used quantitative real-time PCR to analyze the gene expression profiles of all MCM family members in Grade IV (GBM) tissue samples and observed a significant upregulation in GBM samples compared with normal white matter tissues. In addition, we compared the observed gene expression profiles with those of Grade II and Grade III astrocytoma samples and determined that the observed upregulation was restricted and specific to Grade IV. MCM7 was the most upregulated gene in the gene set we analyzed, and therefore we wanted to identify the role of MCM7 in GBM progression. We determined that siRNA-mediated knockdown of MCM7 expression reduced GBM cell proliferation and also inhibited tumor growth in both xenograft and orthotopic mouse models of GBM. Taken together, our data suggest that MCM7 can be a potential prognostic marker and a novel therapeutic target in GBM therapy.