Similar Datasets
Project description:Deregulated gene expression is a hallmark of cancer, however most studies to date have analyzed short-read RNA-sequencing data with inherent limitations. Here, we combine PacBio long-read isoform sequencing (Iso-Seq) and Illumina paired-end short read RNA sequencing to comprehensively survey the transcriptome of gastric cancer (GC), a leading cause of global cancer mortality. We performed full-length transcriptome analysis across 10 GC cell lines covering four major GC molecular subtypes (chromosomal unstable, Epstein-Barr positive, genome stable and microsatellite unstable). We identify 60,239 non-redundant full-length transcripts, of which >66% are novel compared to current transcriptome databases. Novel isoforms are more likely to be cell-line and subtype specific, expressed at lower levels with larger number of exons, with longer isoform/coding sequence lengths. Most novel isoforms utilize an alternate first exon, and compared to other alternative splicing categories are expressed at higher levels and exhibit higher variability. Collectively, we observe alternate promoter usage in 25% of detected genes, with the majority (84.2%) of known/novel promoter pairs exhibiting potential changes in their coding sequences. Mapping these alternate promoters to TCGA GC samples, we identify several cancer-associated isoforms, including novel variants of oncogenes. Tumor-specific transcript isoforms tend to alter protein coding sequences to a larger extent than other isoforms. Analysis of outcome data suggests that novel isoforms may impart additional prognostic information. Our results provide a rich resource of full-length transcriptome data for deeper studies of GC and other gastrointestinal malignancies.
2021-02-02 | PXD023373 | Pride
Project description:BackgroundDeregulated gene expression is a hallmark of cancer; however, most studies to date have analyzed short-read RNA sequencing data with inherent limitations. Here, we combine PacBio long-read isoform sequencing (Iso-Seq) and Illumina paired-end short-read RNA sequencing to comprehensively survey the transcriptome of gastric cancer (GC), a leading cause of global cancer mortality.ResultsWe performed full-length transcriptome analysis across 10 GC cell lines covering four major GC molecular subtypes (chromosomal unstable, Epstein-Barr positive, genome stable and microsatellite unstable). We identify 60,239 non-redundant full-length transcripts, of which > 66% are novel compared to current transcriptome databases. Novel isoforms are more likely to be cell line and subtype specific, expressed at lower levels with larger number of exons, with longer isoform/coding sequence lengths. Most novel isoforms utilize an alternate first exon, and compared to other alternative splicing categories, are expressed at higher levels and exhibit higher variability. Collectively, we observe alternate promoter usage in 25% of detected genes, with the majority (84.2%) of known/novel promoter pairs exhibiting potential changes in their coding sequences. Mapping these alternate promoters to TCGA GC samples, we identify several cancer-associated isoforms, including novel variants of oncogenes. Tumor-specific transcript isoforms tend to alter protein coding sequences to a larger extent than other isoforms. Analysis of outcome data suggests that novel isoforms may impart additional prognostic information.ConclusionsOur results provide a rich resource of full-length transcriptome data for deeper studies of GC and other gastrointestinal malignancies.
| S-EPMC7821541 | biostudies-literature
Project description:Although recent advances in high-throughput technology have provided many insights into gastric cancer (GC), few reliable biomarkers for handling diffuse type GC are identified. Here, we aim to identify a signature classifying high risk diffuse type GC. To identify molecular subtypes of diffuse type GC, we generated RNA-seq based transcriptome data, which were generated using normal mucosa and tumor cells from 140 fresh frozen tissues including diffuse type GCs (n = 107). Unsupervised hierarchical cluster analysis of the RNA-seq data revealed three distinct subgroups of GC. Based on these subtypes, we generated a signature reflecting the best characteristics of aggressive diffuse type GC. When estimating prognostic value, the signature showed a strong prediction ability and an independent clinical utility in diffuse type GC patients. Our signature represents a promising diagnostic tool for the identification of diffuse type GC patients that have a high risk of poor clinical behavior.
2020-03-18 | GSE113255 | GEO
Project description:The aim of the study will be to analyze the microbiome in the blood and stomach in patients with intestinal metaplasia (IM) and / or gastric cancer (GC). As far as IM is concerned, it has been found that the incomplete type is related to GC mainly intestinal-type. Studies show differences in the microbiome in patients with IM and in patients with GC, but do not specify whether these differences are related to histological types.
Our intention is to further analyze the microbiome based on histological types. Most studies on stomach cancer have focused on the microbiota of gastric microbiota. Recent data have shown that the microbiome of the small intestine, especially the mucosa, can play a key role in the condition of the gastrointestinal tract. Disturbance of the microbiome of the small intestine has been found in celiac disease, chronic liver disease, diabetes and irritable bowel syndrome. However, information on the role of the microbiome in IM remains limited.
| 2337510 | ecrin-mdr-crc
Project description:Increasing evidence has clarified that the tumor microenvironment (TME) is closely related to the prognosis and therapeutic efficacy of gastric cancer (GC). However, there is no reliable TME evaluation system used to accurately predict the prognosis and therapeutic efficacy of gastric cancer. In this study, immune cell enrichment analysis was used to construct an immune microenvironment score (IMS).We further demonstrated that IMS may be used as an indicator to predict the efficacy of immunotherapy in patients with GC.
2021-07-29 | GSE180887 | GEO
Project description:An in-depth understanding of the tumor microenvironment (TME) is required for the development of improved combination immunotherapies for gastric cancer. Recently, we classified these cancers into four main types defined by their immunological attributes, namely Hot 1, Hot 2, Intermediate and Cold. Of these, the T cell-inflamed "Hot" tumors were further divided into Hot 1 and Hot 2 with different clinical outcomes. Thus, overall survival and progression-free survival of patients with Hot 1 tumors were shorter than with Hot 2. In the present study, we re-evaluated RNA-Seq data of 6 Hot 1 and 6 Hot 2 gastric cancers to elucidate the underlying reason for the poor prognosis and T cell dysfunction in the former. In addition, 56 Hot 1 and 27 Hot 2 tumors in The Cancer Genome Atlas (TCGA) were analyzed. We report that single sample Gene Set Enrichment Analysis (ssGSEA) and differential gene expression analysis identified differences between Hot 1 and Hot 2 tumors involved in metabolism and cell adhesion pathways. Therefore, it is suggested that strategies to modulate active metabolism in Hot 1 tumors should be integrated into the treatment of these gastric cancers.
| S-EPMC8579120 | biostudies-literature
Project description:Recent studies have demonstrated that the non-coding genome can produce unannotated proteins as antigens that induce immune response. One major source of this activity is the aberrant epigenetic reactivation of transposable elements (TEs). In tumors, TEs often provide cryptic or alternate promoters, which can generate transcripts that encode tumor-specific unannotated proteins. Thus, TE-derived transcripts have the potential to produce tumor-specific, but recurrent, antigens shared among many tumors. Identification of TE-derived tumor antigens holds the promise to improve cancer immunotherapy approaches; however, current genomics and computational tools are not optimized for their detection. Here we combined CAGE technology with full-length long-read transcriptome sequencing (Long-Read CAGE, or LRCAGE) and developed a suite of computational tools to significantly improve immunopeptidome detection by incorporating TE-derived and other tumor transcripts into the proteome database. By applying our methods to human lung cancer cell line H1299 data, we demonstrated that long-read technology significantly improves mapping of promoters with low mappability scores and LRCAGE guarantees accurate construction of uncharacterized 5’ transcript structure. Unannotated peptides predicted from newly characterized transcripts were readily detectable in whole cell lysate mass-spectrometry data. Incorporating unannotated peptides into the proteome database enabled us to detect non-canonical antigens in HLA-pulldown LC-MS/MS data. At last, we showed that epigenetic treatment increased the number of non-canonical antigens, particularly those encoded by TE-derived transcripts, which might expand the pool of targetable antigens for cancers with low mutational burden.
2023-09-23 | PXD040265 | Pride
Project description:Enhancer as a cis-regulatory element (CRE), plays a critical role in gene regulation at many stages of cell growth. Meanwhile, enhancers in cancer cells also act as a regulator controlling oncogene transcription. In this study, we did a comprehensive analysis of long-range chromatin interactions, histone modifications, chromatin status, and expressions of two gastric cancer (GC) cell lines, compared with a human normal epithelial cell line. We found that GC-specific enhancers marked by histone modifications in gastric cancer can activate a population of genes including some oncogenes by enhancer-promoter (E-P) interactions. In addition, motif analysis of E-P interacted enhancers showed that three GC-specific TF sequences may regulate enhancer-interacting gene activation. We found MYB which is crucial for GC cellular growth and is activated by TCF7 regulated E-P loop. To validate this mechanism, we applied CRISPRi (dCas9-KRAB) induced transcriptional regulatory element inactivation in our target enhancer, the growth assay resulted in significant inhibition of cell growth in two GC cell lines. In conclusion, we found oncogene activation by aberrant loop formation that contributes to tumorigenesis in GC.
2024-04-22 | GSE262406 | GEO
Project description:Enhancer as a cis-regulatory element (CRE), plays a critical role in gene regulation at many stages of cell growth. Meanwhile, enhancers in cancer cells also act as a regulator controlling oncogene transcription. In this study, we did a comprehensive analysis of long-range chromatin interactions, histone modifications, chromatin status, and expressions of two gastric cancer (GC) cell lines, compared with a human normal epithelial cell line. We found that GC-specific enhancers marked by histone modifications in gastric cancer can activate a population of genes including some oncogenes by enhancer-promoter (E-P) interactions. In addition, motif analysis of E-P interacted enhancers showed that three GC-specific TF sequences may regulate enhancer-interacting gene activation. We found MYB which is crucial for GC cellular growth and is activated by TCF7 regulated E-P loop. To validate this mechanism, we applied CRISPRi (dCas9-KRAB) induced transcriptional regulatory element inactivation in our target enhancer, the growth assay resulted in significant inhibition of cell growth in two GC cell lines. In conclusion, we found oncogene activation by aberrant loop formation that contributes to tumorigenesis in GC.
2024-04-22 | GSE247537 | GEO
Project description:Enhancer as a cis-regulatory element (CRE), plays a critical role in gene regulation at many stages of cell growth. Meanwhile, enhancers in cancer cells also act as a regulator controlling oncogene transcription. In this study, we did a comprehensive analysis of long-range chromatin interactions, histone modifications, chromatin status, and expressions of two gastric cancer (GC) cell lines, compared with a human normal epithelial cell line. We found that GC-specific enhancers marked by histone modifications in gastric cancer can activate a population of genes including some oncogenes by enhancer-promoter (E-P) interactions. In addition, motif analysis of E-P interacted enhancers showed that three GC-specific TF sequences may regulate enhancer-interacting gene activation. We found MYB which is crucial for GC cellular growth and is activated by TCF7 regulated E-P loop. To validate this mechanism, we applied CRISPRi (dCas9-KRAB) induced transcriptional regulatory element inactivation in our target enhancer, the growth assay resulted in significant inhibition of cell growth in two GC cell lines. In conclusion, we found oncogene activation by aberrant loop formation that contributes to tumorigenesis in GC.
2024-04-22 | GSE247536 | GEO