Spatial total RNA sequencing of formalin-fixed paraffin embedded tissue by Spatial Random-seq
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE247881 | GEO | 2023/12/31
REPOSITORIES: GEO
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Project description:Formalin-fixed, paraffin-embedded (FFPE) tissues are banked in large repositories as a cost-effective means of preserving invaluable specimens for subsequent study, including for clinical proteomics in translational medicine. With the rapid growth of spatial proteomics, FFPE tissue samples can serve as a more accessible alternative to commonly used fresh frozen tissues. However, extracting proteins from FFPE tissue for analysis by mass spectrometry has been challenging due to crosslinks formed between proteins and formalin, particularly when studying limited samples. We have previously demonstrated that nanoPOTS (Nanodroplet Processing in One Pot for Trace Samples) is an enabling technology for high-resolution and in-depth spatial and single-cell proteomics measurements, but only fresh frozen tissues had been previously analyzed. Here we have adapted the nanoPOTS sample processing workflows for proteome profiling of 10-µm-thick FFPE tissues with lateral dimensions as small as 50 µm. Following a comparison of extraction solvents, times, and temperatures, and under the most favorable conditions, we respectively identified an average of 1180 and 2990 proteins from FFPE preserved mouse liver tissues having dimensions of 50 µm and 200 µm. This was on average 87% of the coverage achieved for fresh frozen mouse liver samples analyzed with the same general procedure. We also characterized the performance of our fully automated sample preparation and analysis workflow, termed autoPOTS, for FFPE spatial proteomics. These workflows provide the greatest depth of coverage reported to date for high-resolution spatial proteomics applied to FFPE tissues.
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Project description:Novel In-insert FFPE proteomics combines single glass insert FFPE tissue processing with spatial quantitative data-independent mass spectrometry (DIA). In-insert proteomics represents a blueprint in spatial FFPE tissue subsection processing by completely omitting the robotic platform, desalting prior to injection to the liquid chromatograph and detergent removal while restraining protein losses to the minimum. In-insert proteomics has a sufficient sensitivity to preserve spatial context within a single FFPE tissue slide. Spatial pathway regulation trends were evaluated between 17 individual breast tissue voxels by the method. Bioinformatic spatial analysis of the most dysregulated proteins was performed to reveal hotspots of certain biochemical signaling/processes. A special attention was given to cytoskeleton reorganization as an effect of hormone signaling.
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Project description:Spatial transcriptomics facilitates the understanding of gene expression within complex tissue contexts. Among the array of spatial capture technologies available is 10x Genomics’ Visium which provides whole tissue section profiling, enabling whole transcriptome spatial analysis. Our dataset comprises spleen tissue from mice infected with malaria, spanning multiple experiments and sample preparation protocols for tissue preservation, either as fresh frozen at optimal cutting temperature (OCT) or formalin-fixed paraffin-embedded (FFPE). Tissue placement was also considered, comparing direct tissue placement on the slide with the use of CytAssist (CA), which expands the Visium platform’s capabilities by allowing for the pre-selection of tissue sections and genes through a set of probes. We also include a matching scRNA-seq dataset that can be integrated with the spatial data.
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Project description:For the effectiveness of targeted immunotherapy, which is currently one of the most promising treatments for brain tumors, it is necessary to know specific tumor-associated antigens (TAA). This project aimed to validate the suitability of formalin-fixed and paraffin-embedded (FFPE) material instead of fresh-frozen material for RNA sequencing and downstream TAA identification. Purpose: Detect potential oligodendroglioma-associated antigens using both fresh-frozen and FFPE brain tissues; assess the suitability of the FFPE material for TAA identification. Results: A comparative analysis based on the RNA-seq of canine oligodendroglioma showed that formalin fixation of the samples had a significant effect on the RNA-seq library in terms of quality. Read distribution analysis showed that the FFPE samples contained fewer reads mapping to exonic regions and were enriched with reads mapped to introns and intergenic regions, while the fresh-frozen samples were mostly enriched in reads mapping to exons. Mismatch profile and SNVs calling analyses revealed some substitution artefacts present in the FFPE samples and absent in the corresponding fresh-frozen samples. However, according to the Principal Component Analysis, 36% of the variance between the samples could be explained by the types of conservation, while 43% of the variance could still be attributed to different expression profiles between oligodendroglioma and control conditions. A differential expression analysis of fresh-frozen oligodendroglioma versus fresh-frozen control samples identified 62 potential TAA strongly up-regulated in tumor tissue. The same analysis using the FFPE samples showed 80% of these genes (49/62) also to be differentially expressed. Comparative analysis showed good agreement between FFPE and fresh-frozen RNA-seq libraries in terms of the accuracy of gene expression measurements indicating that archived FFPE tissue can be used for identification of TAA candidates by RNA-seq providing a wealthy source of clinical samples for research. The following 10 genes encoding cell surface proteins have been identified by both approaches as potential TAA candidates based on their strong overexpression in oligodendrogliomas: PDGFRA, NOTCH1, DLL1, GPER1, TNR, IQGAP3, CD44, ERBB3, BCAS1 and ROR2. Future projects still need to investigate their suitability as TAA for targeted immunotherapy. Conclusion: Formalin fixation of the samples had a significant impact on the RNA-seq quality in terms of the accuracy of gene expression measurements, as well as the quality of the nucleotide sequences. Nevertheless, the comparative analysis showed good agreement between FFPE and fresh-frozen RNA-seq libraries.
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Project description:The proteomics of archival samples has advanced significantly during the last two decades, making possible the use of vast FFPE tissue archives in biomarker studies. However, due to the limited data regarding comparison of the performance of different protocols, there is currently no consensus on the most effective protocol for shotgun proteomic analysis of FFPE tissue. In-solution digestion method using Rapigest as detergent and FASP method, both reported to deliver superior results on FFPE tissues were compared using two label-free data-independent LC-MS/MS acquisition modes. Archival FFPE prostate tissues stored 7 years and mirroring fresh frozen samples were processed with both protocols in 3 technical replicates. Data were comparatively evaluated in terms of protein and peptide identifications in fresh frozen and FFPE samples, analysis of the fresh and FFPE tissues representative proteome (molecular weight distribution, distribution according to protein’s pI, cellular component analysis of proteins and quantitation accuracy) and technical reproducibility of the Rapigest and FASP protocols.
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Project description:MicroRNAs (miRs) are non-coding RNA molecules involved in post-transcriptional regulation, with diverse functions in tissue development, differentiation, cell proliferation and apoptosis. miRs may be less prone to degradation during formalin fixation, facilitating miR expression studies in formalin-fixed paraffin-embedded (FFPE) tissue. Our study demonstrates that the TaqMan Human MicroRNA Array v1.0 (Early Access) platform is suitable for miR expression analysis in FFPE tissue with a high reproducibility (correlation coefficients of 0.95 between duplicates, p<0.00001) and outlines the optimal performance conditions of this platform using clinical FFPE samples. We outline a method of data analysis looking at differences in miR abundance between FFPE and fresh-frozen samples. By dividing the profiled miR into abundance strata of high (Ct<30), medium (30<Ct<35), and low (Ct>35), we show that reproducibility between technical replicates, equivalent dilutions, and FFPE vs. frozen samples is best in the high abundance stratum. We also demonstrate that the miR expression profiles of FFPE samples are comparable to those of fresh-frozen samples, with a correlation of up to 0.87 (p<0.001), when examining all miRs, regardless of RNA extraction method used. Examining correlation coefficients between FFPE and fresh-frozen samples in terms of miR abundance reveals correlation coefficients of up to 0.32 (low abundance), 0.70 (medium abundance) and up to 0.97 (high abundance). Our study aims to demonstrate the utility, reproducibility, and optimization steps needed in miR expression studies using FFPE samples on a high-throughput quantitative PCR-based miR platform, opening up a realm of research possibilities for retrospective studies.
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Project description:High density SNP microarrays provide insight into the genomic events that occur in diseases like cancer by their capability to measure both LOH and genomic copy numbers. Where currently available methods are restricted to the use of fresh frozen tissue, we now describe the design and validation of copy number measurements using the Illumina BeadArray platform and its application to formalin fixed, paraffin embedded (FFPE) tissue. In fresh frozen tissue, using a set of colorectal tumors with numerous chromosomal aberrations, our method measures copy number patterns that are comparable to values from established platforms, like Affymetrix GeneChip and BAC array-CGH. Moreover, paired comparisons of fresh frozen and FFPE tissue showed nearly identical patterns of genomic changes. We conclude that this method enables the use of paraffin embedded material for research into both LOH and numerical chromosomal abnormalities. These findings make the large pathological archives available for genomic analysis, which could be especially relevant for hereditary disease where fresh material from affected relatives is rarely available. Keywords: platform comparison and method development
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Project description:Formalin-fixed paraffin-embedded (FFPE) tissues are a vast resource of annotated clinical samples. As such, they represent highly desirable and informative materials for the application of high-definition genomics for improved patient management and to advance the development of personalized therapeutics. However, a limitation of FFPE tissues is the variable quality of DNA extracted for analyses. Furthermore, admixtures of non-tumor and polyclonal neoplastic cell populations limit the number of biopsies that can be studied and make it difficult to define cancer genomes in patient samples. To exploit these valuable tissues, we applied flow cytometry-based methods to isolate pure populations of tumor cell nuclei from FFPE tissues and developed a methodology compatible with oligonucleotide array CGH and whole exome sequencing analyses. These were used to profile a variety of tumors (breast, brain, bladder, ovarian and pancreas), including the genomes and exomes of matching fresh frozen and FFPE pancreatic adenocarcinoma samples.
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