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: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:In summary, we present a systematic in silico screen for the conserved non-coding RNA structures by comparing the P. falciparum genome with seven other malaria species and describe 668 candidate RNA secondary structures. By combining microarray and northern data, we provide evidence for expression of 28 novel ncRNA candidates at the transcript level in the blood stages of P. falciparum, a subset of which show intra-erythrocytic stage-specificity for expression. Few of the expressed novel candidates appear to have similarity to functionally known ncRNAs characterised to-date. The ncRNA candidates that show a narrow phylogenetic distribution, such as the internal var-associated ncRNAs, may be involved in species-specific function. At present, we can not assign specific function to these novel ncRNAs, however, our study highlights the abundance of these novel ncRNA structures in P. falciparum and suggests important roles for these ncRNAs in cellular processes. Although the control of gene expression by mechanisms such as epigenetics, post-transcriptional gene regulation and transcript stability has been recently shown in Plasmodium, all the key cellular players in such types of non-conventional gene regulation in Plasmodium are yet to be identified. Taking cues from the functionally characterized components of the higher eukaryotic non-coding RNA populations, it is tempting to speculate that ncRNAs may, at least in part, be instrumental in gene regulation in P. falciparum. However, in contrast to the higher eukaryotes, the absence of a conventional RNAi pathway and its associated components in malaria suggests that these malaria-specific novel ncRNAs, where functional, must exert their role using novel pathways or mechanisms, possibly unique to malaria. It remains to be determined what fraction of the ncRNAs described here are involved in modulating expression of one or more genes or gene families in malaria and also the precise cellular function for them not only in the blood stages but also in the other life-cycle stages of P. falciparum.

Project description:Transcriptional profiling of LNCaP prostate cancer cells comparing control siRNA-treated LNCaP cells with LNCaP cells treated with siRNAs targeting Prostate Cancer Associated Transcript-1 (PCAT1), an uncharacterized long non-coding RNA. High-throughput sequencing of polyA+ RNA (RNA-Seq) in human cancer shows remarkable potential to identify both novel disease-specific markers for clinical uses and uncharacterized aspects of tumor biology, particularly non-coding RNA (ncRNA) species. To illustrate this approach, we employed RNA-Seq on a cohort of 102 prostate tissues and cells lines and found that aberrant expression profiles of novel tissue-specific ncRNAs distinguished benign, cancerous, and metastatic tumors. Among these, a novel prostate-cancer specific ncRNA (termed PCAT-1) defined a subset of aggressive cancers with low expression of the epigenetic regulator EZH2, a component of the Polycomb Repressive Complex 2 (PRC2) commonly upregulated in metastatic cancers. In vitro assays for core PRC2 genes indicated that the PRC2 complex directly binds and represses PCAT-1, and that the PCAT-1 transcript reciprocally binds PRC2, suggesting a regulatory feedback mechanism. Importantly, knockdown of PCAT-1 in cells with high levels of endogenous PCAT-1 transcript showed changes in cell proliferation and transcriptional regulation of several key biological processes, including cell cycle. Finally, we showed that ncRNA expression signatures, including PCAT-1, were effective for the non-invasive detection of prostate cancer, and that high ncRNA expression signature values correlate with high-grade histology. The findings presented herein establish the utility of RNA-Seq to comprehensively identify unannotated ncRNAs that define human disease states and characterize PCAT-1 as a novel regulator of cell proliferation mechanistically linked to PRC2 and contributory to translational clinical tests for prostate cancer. Two-condition experiment: Control-siRNA-treated versus PCAT1-siRNA-treated LNCaP cells. Biological replicates: 3 control replicates, 3 treatment replicates.

Project description:Myelodysplastic syndromes (MDS) are a group of clonal hematological disorders characterized by ineffective hematopoiesis with morphological evidence of marrow cell dysplasia resulting in peripheral blood cytopenia. Microarray technology has permitted a refined high-throughput mapping of the transcriptional activity in the human genome. Noncoding-RNAs (ncRNAs) transcribed from intronic regions of genes are involved in a number of processes related to post-transcriptional control of gene expression, and in the regulation of exon-skipping and intron retention. Characterization of ncRNAs in progenitor cells and stromal cells of MDS patients could be strategic for understanding gene expression regulation in this disease. In this study, gene expression profiles of CD34+ and stromal cells of MDS patients with refractory anemia with ringed sideroblasts (RARS) subgroup were compared those of healthy individuals, using 44k combined intron-exon oligoarrays, which included probes for protein-coding genes, for sense and antisense strands of totally intronic noncoding (TIN) and for partially intronic noncoding (PIN) RNAs. In CD34+ cells of MDS-RARS patients, 217 genes were significantly differentially expressed (q-value < 0.01) in comparison to healthy individuals, of which 68 (31%) were noncoding transcripts. In stromal cells of MDS-RARS, 13 genes were significantly differentially expressed (q-value < 0.05) in comparison to healthy individuals, of which 4 (30%) were noncoding transcripts. These results demonstrated, for the first time, in CD34+ cells and stromal cells the differential ncRNA expression profile between MDS-RARS and healthy individuals, suggesting that ncRNAs may play an important role during the development of myelodysplastic syndromes. Bone marrow (BM) CD34+ cell samples were collected from 4 healthy subjects and from 4 MDS patients. Stromal samples were collected from 4 healthy subjects and 3 MDS patients. All patients were diagnosed as RARS according to the French-American-British (FAB) classification and did not present chromosomal abnormalities; they received no growth factors or any further MDS treatment.

Dataset Information

Long intronic non-coding RNA from the KLHL29 locus regulates proliferation of human tumorigenic cell lines

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets