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Functional evidence that Drosha over-expression in cervical squamous cell carcinoma affects cell phenotype and microRNA profiles

ABSTRACT: Although gain of chromosome-5p is one of the most frequent DNA copy number imbalances in cervical squamous cell carcinoma (SCC), the genes that drive its selection remain poorly understood. In a previous cross-sectional clinical study we showed that the microRNA processor Drosha (located on chromosome-5p) demonstrates frequent copy-number gain and over-expression in cervical SCC, associated with altered microRNA profiles. Here, we have conducted gene depletion/over-expression experiments to demonstrate the functional significance of up-regulated Drosha in cervical SCC cells. Drosha depletion by RNA-interference (RNAi) produced significant, specific reductions in cell motility/invasiveness in vitro, with a silent RNAi-resistant Drosha mutation providing phenotype rescue. Unsupervised hierarchical clustering following global profiling of 319 microRNAs in eighteen cervical SCC cell line specimens generated two groups according to Drosha expression levels. Altering Drosha levels in individual SCC lines changed the group into which the cells clustered, with gene depletion effects being rescued by the RNAi-resistant mutation. Forty-five microRNAs showed significant differential expression between the groups, including four of fourteen that were differentially-expressed in association with Drosha levels in clinical samples. miR-31 up-regulation in Drosha over-expressing samples/cell lines was the highest-ranked change (by adjusted p-value) in both analyses, an observation validated by Northern blotting. These functional data support the role of Drosha as an oncogene in cervical SCC, by affecting expression of cancer-associated microRNAs that have the potential to regulate numerous protein-coding genes. This SuperSeries is composed of the SubSeries listed below.

ORGANISM(S): Merkel cell polyomavirus Human alphaherpesvirus 2 Betapolyomavirus hominis Human alphaherpesvirus 1 Lymphocryptovirus JC polyomavirus Betapolyomavirus macacae Homo sapiens Human immunodeficiency virus 1 Human betaherpesvirus 5 Rhadinovirus

PROVIDER: GSE26177 | GEO | 2011/05/26

SECONDARY ACCESSION(S): PRJNA135259

REPOSITORIES: GEO

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Project description:Although gain of chromosome-5p is one of the most frequent DNA copy number imbalances in cervical squamous cell carcinoma (SCC), the genes that drive its selection remain poorly understood. In a previous cross-sectional clinical study we showed that the microRNA processor Drosha (located on chromosome-5p) demonstrates frequent copy-number gain and over-expression in cervical SCC, associated with altered microRNA profiles. Here, we have conducted gene depletion/over-expression experiments to demonstrate the functional significance of up-regulated Drosha in cervical SCC cells. Drosha depletion by RNA-interference (RNAi) produced significant, specific reductions in cell motility/invasiveness in vitro, with a silent RNAi-resistant Drosha mutation providing phenotype rescue. Unsupervised hierarchical clustering following global profiling of 319 microRNAs in eighteen cervical SCC cell line specimens generated two groups according to Drosha expression levels. Altering Drosha levels in individual SCC lines changed the group into which the cells clustered, with gene depletion effects being rescued by the RNAi-resistant mutation. Forty-five microRNAs showed significant differential expression between the groups, including four of fourteen that were differentially-expressed in association with Drosha levels in clinical samples. miR-31 up-regulation in Drosha over-expressing samples/cell lines was the highest-ranked change (by adjusted p-value) in both analyses, an observation validated by Northern blotting. These functional data support the role of Drosha as an oncogene in cervical SCC, by affecting expression of cancer-associated microRNAs that have the potential to regulate numerous protein-coding genes. This SuperSeries is composed of the following subset Series: GSE26175: Functional evidence that Drosha over-expression in cervical squamous cell carcinoma affects cell phenotype and microRNA profiles [miRNA] GSE26176: Functional evidence that Drosha over-expression in cervical squamous cell carcinoma affects cell phenotype and microRNA profiles [mRNA] Refer to individual Series

Project description:Little is known about the alterations in microRNA (miRNA) expression patterns during the consecutive stages of cervical cancer development and their association with chromosomal instability and epigenetic changes. We integrated miRNA expression profiles in normal cervical squamous epithelium, high-grade precancerous lesions (CIN2-3), squamous cell carcinomas (SCC) and adenocarcinomas (AdCAs) with previously generated chromosomal profiles of the same samples. In addition, the DNA methylation status of downregulated miRNAs located in a CpG island was determined. Significantly differential expression during the consecutive stages of cervical SCC development was observed for 106 miRNAs. Altered expression of 5 significantly differentially expressed miRNAs, hsa-miR-9 (1q23.2), hsa-miR-15b (3q25.32), hsa-miR-28-5p (3q27.3), hsa-miR-100 and hsa-miR-125b (both 11q24.1) was directly linked to frequent chromosomal alterations. Another 9 significantly downregulated miRNAs were located within a CpG island. Three of these 9 miRNAs, hsa-miR-203, hsa-miR-572, and hsa-miR-638, showed increased methylation in cervical cancer cell lines and HPV-immortalised cells compared to primary keratinocytes. Functional analyses were performed for hsa-miR-9, representing a potential oncogene with increased expression linked to a chromosomal gain, and hsa-miR-203, representing a potential tumour suppressor gene silenced by DNA methylation. Hsa-miR-9 and hsa-miR-203 were found to alter cell viability and anchorage independent growth in vitro, respectively, supporting their oncogenic and tumour suppressive function in cervical cancer. In conclusion, differential expression of 106 miRNAs, partly associated with chromosomal alterations and epigenetic changes, was observed during cervical SCC development. Altered expression of hsa-miR-9 and hsa-miR-203 was shown to be functionally relevant, underlining the importance of deregulated miRNA expression in cervical carcinogenesis. 10 squamous cell carcinomas of the cervix, 9 adenocarcinomas of the cervix, 18 high-grade cervical intraepithelial neoplasias (CIN2-3), and 10 cervical squamous epithelial samples with normal histology were analysed using single channel (Cy3) miRNA microarrays from Agilent (G4471A-016436).

Project description:For many oncogenes, increased expression resulting from copy number gain confers a selective advantage to cells that consequently make up the tumour bulk. To identify oncogenes of potential biological significance in cervical squamous cell carcinoma (SCC), 36 primary samples and ten cell lines were screened by array comparative genomic hybridization (CGH). The most commonly occurring regions of copy number gain that also showed amplification were 5p15.2–14.3 (59%), 5p13.3 (65%), and 5p13.2–13.1 (63%). Gene copy numbers were significantly associated with expression levels for three candidate oncogenes at these loci: OSMR (oncostatin M receptor) (p = 0.03), PDZK3 (PDZ domain containing protein 3) (p = 0.04), and TRIO (triple functional domain) (p = 0.03). Further examination by fluorescence in situ hybridization on a tissue microarray of 110 primary cervical SCC samples revealed copy number gain frequencies of 60.9%, 57.3%, and 54.5% for OSMR, PDZK3, and TRIO, respectively, with OSMR adversely influencing overall patient survival independently of tumour stage (p = 0.046). By array CGH, copy number gain of OSMR was not seen in any of 40 microdissected precursor cervical squamous intraepithelial lesions (SILs). Moreover, global mRNA expression analysis, using Affymetrix U133A 2.0 Arrays, showed no overexpression of OSMR in SILs, suggesting that OSMR gain and overexpression are relatively late steps in cervical carcinogenesis. In the cervical SCC cell lines CaSki and SW756, exogenous OSM activated downstream-signalling elements of OSMR including STAT3, p44/42 MAPK, and S6 ribosomal protein, and induced transcription of the angiogenic factor VEGF, effects that were reduced by OSMR depletion using RNA interference. We conclude that copy number gain of OSMR is frequently found in cervical SCC and is associated with adverse clinical outcome. As well as being a potential prognostic marker, OSMR is a candidate cell surface therapeutic target 36 primary cervical SCC samples, and 10 cervical SCC cell lines were subject to 1 Mb aCGH using a dye swapped approach. Two samples were subject to repeat. (J Pathol. 2007 Jul;212(3):325-34.)

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Functional evidence that Drosha over-expression in cervical squamous cell carcinoma affects cell phenotype and microRNA profiles

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