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MicroRNA profiling in colorectal cancer highlights miR-1 involvement in MET-dependent proliferation

ABSTRACT: Abstract: Altered expression of microRNAs (miRNAs) is associated with development and progression of various human cancers by regulating the translation of oncogenes and tumor suppressor genes. In colorectal cancer (CRC), these regulators complement the Vogelstein multi-step model of pathogenesis and have the potential of becoming a novel class of tumor biomarkers and therapeutic targets. Using QRT-PCR, we measured the expression of 621 mature miRNAs in 40 CRCs and their paired normal tissues and identified 23 significantly deregulated miRNAs. We subsequently evaluated their association with clinical characteristics of the samples and presence of alterations in the molecular markers of CRC progression. Expression levels of miR-31 were correlated with CA19-9 and miR-18a, miR-21 and miR-31 were associated with mutations in APC gene. To investigate the downstream regulation of the differentially expressed miRNAs identified we integrated putative mRNA target predictions with the results of a meta-analysis of seven public gene expression datasets of normal and tumor samples of CRC patients. Many of the CRC deregulated miRNAs computationally map to targets involved in pathways related to progression. Here one promising candidate pair (miR-1 and MET) was studied and functionally validated. We show that miR-1 can have a tumor suppressor function in CRC by directly down-regulating MET oncogene both at RNA and protein level and that re-expression of miR-1 leads to MET driven reduction of cell proliferation and motility, identifying the miR-1 down-modulation as one of the events that could enhance CRC progression. Note: Each sample has the following information: Type - tissue type (T : Tumor or N: Normal), Patient - patient identifier, Stage - tumor stage (I - IV), Status - disease status at last check-up (ED: evident disease, NED: non-evident disease), CEA - carcinoembryonic antigen (continuous), CA199 - carbohydrate antigen 19-9 (continuous), APC - mutation status of APC gene (0: wild-type, 1: mutated), KRAS - mutation status of KRAS gene (0: wild-type, 1: mutated), chr18qLOH - LOH status of 18q (0: no LOH, 1: LOH), TP53 - mutation status of TP53 gene (0: wild-type, 1: mutated).

ORGANISM(S): Homo sapiens

PROVIDER: GSE28364 | GEO | 2012/02/22

SECONDARY ACCESSION(S): PRJNA139427

REPOSITORIES: GEO

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Project description:Abstract: Altered expression of microRNAs (miRNAs) is associated with development and progression of various human cancers by regulating the translation of oncogenes and tumor suppressor genes. In colorectal cancer (CRC), these regulators complement the Vogelstein multi-step model of pathogenesis and have the potential of becoming a novel class of tumor biomarkers and therapeutic targets. Using QRT-PCR, we measured the expression of 621 mature miRNAs in 40 CRCs and their paired normal tissues and identified 23 significantly deregulated miRNAs. We subsequently evaluated their association with clinical characteristics of the samples and presence of alterations in the molecular markers of CRC progression. Expression levels of miR-31 were correlated with CA19-9 and miR-18a, miR-21 and miR-31 were associated with mutations in APC gene. To investigate the downstream regulation of the differentially expressed miRNAs identified we integrated putative mRNA target predictions with the results of a meta-analysis of seven public gene expression datasets of normal and tumor samples of CRC patients. Many of the CRC deregulated miRNAs computationally map to targets involved in pathways related to progression. Here one promising candidate pair (miR-1 and MET) was studied and functionally validated. We show that miR-1 can have a tumor suppressor function in CRC by directly down-regulating MET oncogene both at RNA and protein level and that re-expression of miR-1 leads to MET driven reduction of cell proliferation and motility, identifying the miR-1 down-modulation as one of the events that could enhance CRC progression. Note: Each sample has the following information: Type - tissue type (T : Tumor or N: Normal), Patient - patient identifier, Stage - tumor stage (I - IV), Status - disease status at last check-up (ED: evident disease, NED: non-evident disease), CEA - carcinoembryonic antigen (continuous), CA199 - carbohydrate antigen 19-9 (continuous), APC - mutation status of APC gene (0: wild-type, 1: mutated), KRAS - mutation status of KRAS gene (0: wild-type, 1: mutated), chr18qLOH - LOH status of 18q (0: no LOH, 1: LOH), TP53 - mutation status of TP53 gene (0: wild-type, 1: mutated). Tumor and normal counter-parts of 40 colorectal cancer patients (10 of each Stage I to IV) where profiled using TaqMan(r) Array Human MicroRNA A+B Cards v2.0

Project description:Samples were taken from colorectal cancers in surgically resected specimens in 33 colorectal cancer patients. The expression profiles were determined using Affymetrix Human Genome U133 Plus 2.0 arrays. Comparison between the sample groups allow to identify a set of discriminating genes that can be used for molecular markers for CIN phynotype Specimens from 33 consecutive stage II and stage III patients who had undergone surgical resection of CRC were studied. Patients with familial adenomatous polyposis and HNPCC were excluded from the study. Specimens from tumors and corresponding normal tissues in surgically resected specimens were snap-frozen in liquid nitrogen and stored at -80degreesC until use. Parallel tumor specimens were formalin fixed and paraffin embedded for histological examination. DNA and RNA was extracted from paired tumor and normal tissue using frozen samples. The patients provided written, informed consent to the collection of specimens, and the local Ethics Committee approved the study protocol. MSI and LOH phenotype analysis were done as follows; Using DNA, we performed the polymerase chain reaction (PCR) and determined the MSI status. In addition to five microsatellite markers recommended by the National Cancer Institute workshop, we also used TP53, D18S46, D18S363 and D18S474.9 We determined LOH status in non–MSI-high tumors, because LOH is rare in MSI-high tumors and also interpretation of LOH is difficult in MSI-high tumors. We defined LOH at each locus as a 50% reduction in the height of one of two allele peaks in tumor DNA relative to non-neoplastic control DNA. LOH was defined as present if any of the markers on the same chromosome show LOH. In order to evaluate the severity of chromosomal instability based on the actual frequency of LOH among evaluable loci, we defined the LOH Ratio (%) as: LOH Ratio (%) = Total number of chromosomes with LOH / Total number of chromosomes that could be evaluated for LOH × 100. Depending on the LOH Ratio, we classified tumors as having high levels of chromosomal instability (CIN-high) (33% < LOH Ratio < 100%) or low levels of chromosomal instability (CIN-low) (0% < LOH Ratio <33%). Furthermore, CIN-high tumors were divided into two subgroups; CIN-high (mild type) (33% < LOH Ratio < 75%) and CIN-high (severe type) (75% < LOH Ratio <100%).

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MicroRNA profiling in colorectal cancer highlights miR-1 involvement in MET-dependent proliferation

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