Project description:It has been postulated that noncoding RNAs (ncRNAs) are involved in the post-transcriptional control of gene expression, and may have contributed to the emergence of the complex attributes observed in mammalians. The complement of ncRNAs expressed from intronic regions of the human and mouse genomes comprises at least 78,147 and 39,660 transcriptional units, respectively. To identify conserved intronic sequences expressed in both humans and mice, we used custom-designed human cDNA microarrays to separately interrogate RNA from mouse and human liver, kidney and prostate tissues. An overlapping tissue expression signature was detected for both species, comprising 198 transcripts; among these, twenty two RNAs map to intronic regions with evidence of evolutionary conservation in humans and mice. Transcription of selected human-mouse intronic ncRNAs was confirmed using strand specific RT-PCR. Altogether, these results support an evolutionarily conserved role of intronic ncRNAs in human and mouse, which are likely to be involved in the fine tuning of gene expression regulation in different mammalian tissues. Keywords: tissue expression pattern 1. Experiment Design: 1.1. Type of experiment: The experiments described here aim to generate expression profiles from human and mouse prostate, kidney and liver tissue samples using a custom-designed cDNA microarray platform with 4,608 unique elements in replicate (9,216) enriched in gene fragments that map to intronic regions of known human genes. The platform consists of 3,355 probes of human cDNA fragments that map in the human genome sequence either to intronic regions of known genes (822), to unannotated regions of the human genome (241) or to known exons of RefSeq genes (2,292). We separately compared the expression profiles obtained from human and mouse samples to identify sequence conserved tissue-specific intronic transcripts. 1.2. Experimental factors: Tissues from liver, prostate and kidney from five adult male mice of the Balb/c strain were obtained and frozen in liquid nitrogen. Likewise, five non-tumor samples of human prostate, kidney or liver from our tumor bank were selected. All samples were obtained from patients who signed informed consent, and approval was received from the ethics committees of the hospitals. Total RNA was purified from tissues and treated with DNAse to reduce the levels of genomic DNA contaminant. Either human and or mouse samples from for each tissue from the five individuals were separately pooled using equal quantities of RNA. 1.3. The number of hybridizations performed in the experiment. RNA pools from each tissue sample was hybridized twice, performing a total of 18 hybridizations. 1.4. The type of reference used for the hybridizations, if any. All hybridizations included external mRNA spikes for quality control of the experiments (detailed below in section 2.5). Hybridizations were performed as single color experiments. 1.5. Hybridization design: Three aliquots of 15ug of the pool of total RNA from each tissue was labeled with Cy5-dUTP after reverse transcription (CyScribe first strand cDNA labeling kit, Amershan Biosciences) and hybridizations were carried out using all labeled-target in an Automate Slide Processor (Amershan Biosciences). Images were obtained using a Generation III Scanner (Amersham Biosciences). The human and mouse obtained expression data were independently analyzed using a highly stringent methodology, including different statistical approaches (see below for a detailed description). 1.6. Quality control steps taken: Integrity of total RNA was checked by electrophoresis using the Bio Sizing total RNA Nano assay in the 2100 Bioanalyzer (Agilent Technologies). Three replicates of each experiment were performed, as describe in the previous section.

Project description:Pancreatic ductal adenocarcinoma (PDAC) is known by its aggressiveness and lack of effective therapeutic options. Thus, improvement in current knowledge of molecular changes associated with pancreatic cancer is urgently needed to explore novel venues of diagnostics and treatment of this dismal disease. While there is mounting evidence that long noncoding RNAs (ncRNAs) transcribed from intronic and intergenic regions of the human genome may play different roles in the regulation of gene expression in normal and cancer cells, their expression pattern and biological relevance in pancreatic cancer is currently unknown. In the present work we investigated the relative abundance of a collection of ncRNAs in patients’ pancreatic tissue samples aiming at identifying gene expression profiles correlated to pancreatic cancer and metastasis. To investigate the relative abundance, we used a custom 3,355-element spotted cDNA microarray interrogating protein-coding genes and putative ncRNA were used to obtain expression profiles from 38 clinical samples of tumor and non-tumor pancreatic tissues. Bioinformatics analyses were performed to characterize structure and conservation of ncRNAs expressed in pancreatic tissues, as well as to identify expression signatures correlated to tissue histology. Strand-specific reverse transcription followed by PCR and qRT-PCR were employed to determine strandedness of ncRNAs and to validate microarray results, respectively. We found that long intronic/intergenic ncRNAs are ubiquitously expressed across tumor and non-tumor pancreatic tissue samples. Enrichment of promoter-H3K4me3 associated chromatin marks and over-representation of conserved DNA elements and stable secondary structure predictions suggest that these transcripts are generated from independent transcriptional units and that at least a fraction is under evolutionary selection, and thus potentially functional. Statistically significant expression signatures comprising protein-coding mRNAs and long ncRNAs that correlate to PDAC or to pancreatic cancer metastasis were identified. Interestingly, loci harboring intronic ncRNAs differentially expressed in PDAC metastases were enriched in genes associated to the MAPK pathway. Orientation-specific RT-PCR documented that intronic transcripts are expressed in sense, antisense or both orientations relative to protein-coding mRNAs. Differential expression of a subset of intronic ncRNAs (PPP3CB, MAP3K14 and DAPK1 loci) in metastatic samples was confirmed by Real-Time PCR. All this results reveal sets of long intronic ncRNAs expressed in pancreatic tissues whose abundance is correlated to PDAC or metastasis, thus pointing to the potential relevance of this class of transcripts in biological processes related to malignant transformation and metastasis in pancreatic cancer. Fluorescent labeled cDNA targets derived from pancreatic tumor and non-tumor tissue from each patient were combined and hybridized to spotted cDNA microarrays. For each patient, a replicate hybridization was performed. For each sample, there are 4 replicate measurements for each probe.

Project description:Pancreatic ductal adenocarcinoma (PDAC) is known by its aggressiveness and lack of effective therapeutic options. Thus, improvement in current knowledge of molecular changes associated with pancreatic cancer is urgently needed to explore novel venues of diagnostics and treatment of this dismal disease. While there is mounting evidence that long noncoding RNAs (ncRNAs) transcribed from intronic and intergenic regions of the human genome may play different roles in the regulation of gene expression in normal and cancer cells, their expression pattern and biological relevance in pancreatic cancer is currently unknown. In the present work we investigated the relative abundance of a collection of ncRNAs in patients’ pancreatic tissue samples aiming at identifying gene expression profiles correlated to pancreatic cancer and metastasis. To investigate the relative abundance, we used a custom 3,355-element spotted cDNA microarray interrogating protein-coding genes and putative ncRNA were used to obtain expression profiles from 38 clinical samples of tumor and non-tumor pancreatic tissues. Bioinformatics analyses were performed to characterize structure and conservation of ncRNAs expressed in pancreatic tissues, as well as to identify expression signatures correlated to tissue histology. Strand-specific reverse transcription followed by PCR and qRT-PCR were employed to determine strandedness of ncRNAs and to validate microarray results, respectively. We found that long intronic/intergenic ncRNAs are ubiquitously expressed across tumor and non-tumor pancreatic tissue samples. Enrichment of promoter-H3K4me3 associated chromatin marks and over-representation of conserved DNA elements and stable secondary structure predictions suggest that these transcripts are generated from independent transcriptional units and that at least a fraction is under evolutionary selection, and thus potentially functional. Statistically significant expression signatures comprising protein-coding mRNAs and long ncRNAs that correlate to PDAC or to pancreatic cancer metastasis were identified. Interestingly, loci harboring intronic ncRNAs differentially expressed in PDAC metastases were enriched in genes associated to the MAPK pathway. Orientation-specific RT-PCR documented that intronic transcripts are expressed in sense, antisense or both orientations relative to protein-coding mRNAs. Differential expression of a subset of intronic ncRNAs (PPP3CB, MAP3K14 and DAPK1 loci) in metastatic samples was confirmed by Real-Time PCR. All this results reveal sets of long intronic ncRNAs expressed in pancreatic tissues whose abundance is correlated to PDAC or metastasis, thus pointing to the potential relevance of this class of transcripts in biological processes related to malignant transformation and metastasis in pancreatic cancer.

Project description:Many classes of noncoding RNAs (ncRNAs) are known to be involved in gene expression regulation; however, long intronic ncRNAs have received little attention. In previous works, our group has provided evidence that intronic regions, transcribed from 80% of all RefSeq gene loci, are key sources of potentially regulatory ncRNAs. Intronic transcripts were shown to be correlated to the degree of prostate cancer differentiation, regulated by physiological stimuli, and highly expressed in genomic loci related to transcriptional regulation. In the present work we aimed at functional characterization of KLHL29 intronic transcript, one of the most highly expressed in human tissues. Although the protein-coding KLHL29 transcripts are still poorly studied, genes from this family are involved in a wide variety of biological processes, including cell cycle regulation mechanisms. We have observed that the long intronic ncRNA is predominantly transcribed from the opposite strand at the KLHL29 locus, and that the ncRNA overexpression does not affect the levels of protein-coding mRNAs from the same locus. Intriguingly, we found 2,002 genes with significant (q< 5.3%) differential expression between HEK293 cells overexpressing KLHL29 sense (S) or antisense (AS) intronic transcript. Within these genes, GO categories such as ‘Regulation of cell cycle’ and ‘Transcription’ were significantly enriched. Furthermore, human tumorigenic cell lines overexpressing KLHL29 AS intronic transcript showed increased proliferation rates in vitro and increased tumorigenic capacity in nude mice. In conclusion, we suggest that KLHL29 long intronic ncRNA controls the cell cycle mechanisms, probably through a fine-tuning regulation of gene expression. Genes were defined as expressed when their intensity signals were above the average negative control value plus three standard deviations; a set of 153 negative controls (Agilent Technologies) was present on the array. Only genes that were detected as expressed in all four replicates of the same HEK293 transfection (or not expressed in the four replicates) were used in further analysis. The intensity values between experiments were normalized by the 40% trimmed mean intensity. For each transfection, one entire replicate experiment was excluded from the analyses, based on evaluating the coefficient of variance among the samples (for S KLHL29 intronic transcript, exclusion of the outlier replicate decreased the coefficient of variance from 0.21-0.24 (obtained by excluding any other replicate) to 0.19; for AS transcript, the coefficient of variance decreased from 0.17-0.18 to 0.12). Differentially expressed genes were identified using three transfection replicates for each construction, employing the Significance Analysis of Microarrays (SAM) tool (Tusher et al., 2001) with the following parameters: two-class response, 100 permutations and K-Nearest Neighbors Imputer. We applied 5.4 or 10.3% FDR (False Discovery Rate) cutoffs, as described in the results. A fold-change filter (1.4-fold cutoff) was applied after identification of significant differentially expressed genes.

Project description:Intronic and intergenic long noncoding RNAs (lncRNAs) are emerging gene expression regulators. The molecular pathogenesis of renal cell carcinoma (RCC) is still poorly understood, and in particular, limited studies are available for intronic lncRNAs expressed in RCC. Microarray experiments were performed with two different custom-designed arrays enriched with probes for lncRNAs mapping to intronic genomic regions. Samples from 18 primary clear cell RCC tumors and 11 nontumor adjacent matched tissues were analyzed with 4k-probes microarrays. Oligoarrays with 44k-probes were used to interrogate 17 RCC samples (14 clear cell, 2 papillary, 1 chromophobe subtypes) split into four pools. Meta-analyses were performed by taking the genomic coordinates of the RCC-expressed lncRNAs, and cross-referencing them with microarray expression data from three additional human tissues (normal liver, prostate tumor and kidney nontumor samples), and with large-scale public data for epigenetic regulatory marks and for evolutionarily conserved sequences. A signature of 29 intronic lncRNAs differentially expressed between RCC and nontumor samples was obtained (false discovery rate (FDR) <5%). An additional signature of 26 intronic lncRNAs significantly correlated with the RCC five-year patient survival outcome was identified (FDR <5%, p-value M-bM-^IM-$0.01). We identified 4303 intronic antisense lncRNAs expressed in RCC, of which 25% were cis correlated (r >|0.6|) with the expression of the mRNA in the same locus across three human tissues. Gene Ontology (GO) analysis of those loci pointed to M-bM-^@M-^Xregulation of biological processesM-bM-^@M-^Y as the main enriched category. A module map analysis of all expressed protein-coding genes in RCC that had a significant (r M-bM-^IM-%|0.8|) trans correlation with the 20% most abundant lncRNAs identified 35 relevant (p <0.05) GO sets. In addition, we determined that 60% of these lncRNAs are evolutionarily conserved. At the genomic loci containing the intronic RCC-expressed lncRNAs, a strong association (p <0.001) was found between their transcription start sites and genomic marks such as CpG islands and histones methylation and acetylation. Intronic antisense lncRNAs are widely expressed in RCC tumors. Some of them are significantly altered in RCC in comparison with nontumor samples. The majority of these lncRNAs is evolutionarily conserved and possibly modulated by epigenetic modifications. Our data suggest that these RCC lncRNAs may contribute to the complex network of regulatory RNAs playing a role in renal cell malignant transformation. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series

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Conserved tissue expression signatures of intronic noncoding RNAs transcribed from human and mouse loci

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