Unknown,Transcriptomics,Genomics,Proteomics

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Feasibility of unbiased RNA profiling of colorectal tumors: a proof of principle.

ABSTRACT: Liquid biopsy profile which can screen for early CRC. We aimed to depict the profile of early stage CRC as well as for advanced adenomas by combination of current molecular knowledge with microarray technology, using efficient circulating free RNA purification from blood and RNA amplification technologies. Circulating free RNA profile of plasma from colorectal cancer patients, advanced adenomas and healthy colonoscopia subjects. Plasma was drawn from 3 healthy colonoscopia subjects, 4 adanced adenomas subjects and 3 colorectal cancer patients. Circulating free RNA was purified from plasma samples and applied on GeneChip human 1.0 ST Arrays. The 'HuGene_1_0_green_yelow_red_DATASET.xlsx' and 'probe_level_expression_matrix.txt' files contain the primary data that was used to draw the conclusions of the current study. Please note that exon-level' analysis was performed but NO probe summarization to probeset was performed, therefore both data matrices contains non-unique identifiers.

ORGANISM(S): Homo sapiens

SUBMITTER: Vardit Moshayoff

PROVIDER: E-GEOD-83353 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: We aimed to investigate the effects of intravenous immune globulin (IVIG) and rituximab desensitization treatment on kidney transplant rate and blood gene expression profiles by microrarrays. Methods: We enrolled patients with PRA levels >50% and on the deceased-donor waiting list for >5 years. Patients received IVIG (2.0 g/kg) on day 0 and 30; and rituximab (375 mg/m2) on day 15. The antibodies with mean fluorescence intensity (MFI) values > 5,000 were reported to UNET as unacceptable antigens. The gene expression profiles of blood samples collected in PAXGene tube were studied by Affymetrix HuGene 1.0 ST expression arrays. Results: 40 of the 415 patients (10%) on the waiting list were eligible for desensitization treatment and 11 completed the treatment. While 15 of the remaining 29 patients (52%) received a transplant without therapy, only 2 of the 11 desensitized patients (18%) received transplant during a median follow-up of 217 days. While there were no statistically significant difference in demographics, desensitized patients had higher cPRA values (97% vs. 77%, p=0.0005) and more number of unacceptable antigens (39 vs. 10, p=0.0001). There was no significant change in the mean number of unacceptable antigens (39 ± 22 versus 39 ± 23) or reduction in the mean MFI values (11,333 ± 3,133 vs 11,289 ± 3,386). Analysis of genes chosen as significantly differentially expressed revealed downregulation of genes involved in B cells and immune system (CD79a, B and T lymphocyte associated transcript, B cell scaffold protein, CD22, CXCR5, fas apoptotic inhibitory protein). Gene set enrichment analysis using Pathogenesis Based Transcripts created by Edmonton Group demonstrated significant downregulation of B cell associated (p=0.04) and immunoglobulin transcripts (p=0.03). Conclusion: Although, desensitization with IVIG and rituximab decreases the expression of B cell and immunoglobulin associated transcripts, it was not successful in increasing kidney transplant rate or in decreasing the number of unacceptable antigens. Total of 28 arrays included in this study, which corresponding to 9 individuals with paired pre/post treatment samples and an additional 10 untreated control individuals. pair_analysis_normData.txt for paired analysis of pre/post treatment; ordinary_analysis_normData.txt for non-paired analysis include all samples, except for 38 Pax V0 and 56 Pax V1, which shows technicial bias and lowest array quality, hence removed from analysis.

Project description:Background Plasma proteins can be modified by addition of sugar residues by non-enzymatic glycation as well as glycosylation. While glycation is a hallmark of hyperglycemia, glycosylation is a complex, enzyme-catalyzed post-translational modification by heterogeneous sugar chains and is present on a majority of plasma proteins. N-linked glycosylation occurs on asparagine residues occurring predominantly on a canonical N-glycosylation motif (Asn-X-Ser/Thr) although non-canonical N-glycosylation motifs Asn-X-Cys/Val have also been reported to be glycosylated less frequently. Albumin is the most abundant protein in human plasma whose glycation has been implicated in end-organ damage in advanced diabetes mellitus, and as such, has both diagnostic and therapeutic implications. However, albumin has long been regarded as a non-glycosylated protein owing to the absence of canonical motifs. Albumin contains two non-canonical N-glycosylation motifs, of which one was recently reported to be glycosylated with two possible attached glycans. Methods To investigate N-linked glycosylation of abundant serum proteins in greater detail, we passed healthy donor samples through a multiple affinity removal spin (MARS14) column followed by trypsin digestion of bound proteins and subsequent glycopeptide enrichment by size-exclusion chromatography (SEC) or mixed-mode anion-exchange (MAX), in parallel. Global analysis of intact glycopeptides was performed by LC-MS/MS to evaluate potential glycosylation at canonical as well as non-canonical sites. PNGase F treatment was carried out to confirm N-linked glycosylation at non-canonical sites Asn-X-Cys/Val. Glycopeptides on albumin at non-canonical sites were further characterized by MS3 fragmentation from immunoprecipitated albumin to confirm the attached glycans. To assess if the observed glycosylation was a general phenomenon, targeted analysis using parallel reaction monitoring (PRM) was carried out on an independent set of twenty human serum samples. Finally, to test whether albumin glycosylation is unique to human albumin or is a general phenomenon, bovine and rabbit serum albumins were subjected to MAX chromatography and LC-MS/MS analysis. Results We report that human albumin is modified by N-linked glycosylation at two sites, Asn68(-Glu-Val) and Asn123-(Glu-Cys), both of which occur in non-canonical N-glycosylation motifs. We detected N-glycopeptides at both sites bearing four complex mono- and bi-antennary N-linked glycans, with Hex5HexNAc4NeuAc2 and Hex5HexNAc4NeuAc1 being the most abundant glycans. These findings were validated by analyzing deglycosylated peptides and MS3-based fragmentation of glycopeptides. Glycosylation at both sites was confirmed by targeted MS in twenty donor samples. Finally, we report that the Asn residue on bovine and rabbit serum albumins that corresponds to the highly conserved Asn123 in human albumin is also N-glycosylated with complex sialylated glycans similar to those observed in human albumin. Conclusions Albumin is a conserved glycoprotein with multiple N-linked glycosylation sites. This glycosylation of albumin has potential functional implications and applications in medicine.

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Feasibility of unbiased RNA profiling of colorectal tumors: a proof of principle.

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