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Residual tissue repositories as a resource for population-based cancer proteomic studies

ABSTRACT: Background Mass spectrometry-based proteomics has become a powerful tool for the identification and quantification of proteins from a wide variety of biological specimens. To date, the majority of studies utilizing tissue samples have been carried out on prospectively collected fresh frozen or optimal cutting temperature (OCT) embedded specimens. However, such specimens are often difficult to obtain, in limited in supply, and clinical information and outcomes on patients are inherently delayed as compared to banked samples. Annotated formalin fixed, paraffin embedded (FFPE) tumor tissue specimens are available for research use from a variety of tissue banks, such as from the surveillance, epidemiology and end results (SEER) registries' residual tissue repositories. Given the wealth of outcomes information associated with such samples, the reuse of archived FFPE blocks for deep proteomic characterization with mass spectrometry technologies would provide a valuable resource for population-based cancer studies. Further, due to the widespread availability of FFPE specimens, validation of specimen integrity opens the possibility for thousands of studies that can be conducted worldwide. Methods To examine the suitability of the SEER repository tissues for proteomic and phosphoproteomic analysis, we analyzed 60 SEER patient samples, with time in storage ranging from 7 to 32 years; 60 samples with expression proteomics and 18 with phosphoproteomics, using isobaric labeling. Linear modeling and gene set enrichment analysis was used to evaluate the impacts of collection site and storage time. Results All samples, regardless of age, yielded suitable protein mass after extraction for expression analysis and 18 samples yielded sufficient mass for phosphopeptide analysis. Although peptide, protein, and phosphopeptide identifications were reduced by 50, 20 and 76% respectively, from comparable OCT specimens, we found no statistically significant differences in protein quantitation correlating with collection site or specimen age. GSEA analysis of GO-term level measurements of protein abundance differences between FFPE and OCT embedded specimens suggest that the formalin fixation process may alter representation of protein categories in the resulting dataset. Conclusions These studies demonstrate that residual FFPE tissue specimens, of varying age and collection site, are a promising source of protein for proteomic investigations if paired with rigorously verified mass spectrometry workflows.

Dataset imported into MassIVE from https://cptac-data-portal.georgetown.edu/study-summary/S042 on 12/08/21

INSTRUMENT(S): Q Exactive Plus, Q Exactive HF

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Karin D. Rodland

PROVIDER: MSV000088548 | MassIVE | Wed Dec 08 17:51:00 GMT 2021

REPOSITORIES: MassIVE

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Residual tissue repositories as a resource for population-based cancer proteomic studies.

Piehowski Paul D PD Petyuk Vladislav A VA Sontag Ryan L RL Gritsenko Marina A MA Weitz Karl K KK Fillmore Thomas L TL Moon Jamie J Makhlouf Hala H Chuaqui Rodrigo F RF Boja Emily S ES Rodriguez Henry H Lee Jerry S H JSH Smith Richard D RD Carrick Danielle M DM Liu Tao T Rodland Karin D KD

Clinical proteomics 20180803

<h4>Background</h4>Mass spectrometry-based proteomics has become a powerful tool for the identification and quantification of proteins from a wide variety of biological specimens. To date, the majority of studies utilizing tissue samples have been carried out on prospectively collected fresh frozen or optimal cutting temperature (OCT) embedded specimens. However, such specimens are often difficult to obtain, in limited in supply, and clinical information and outcomes on patients are inherently d ...[more]

PMID: 30087585

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Project description:Tissue samples in biobanks preserved by formalin-fixation and paraffin-embedding (FFPE) and/or optimal cutting temperature (OCT)-embedded and subsequently freezing are highly valuable in experimental studies where the results can be related to clinical parameters. Today, mass spectrometry (MS)-based proteomics is the method of choice for unbiased and relative comparison of the abundances of thousands of proteins present in biological samples. MS analysis of FFPE- and OCT-preserved tissue has been limited, but it is now approachable using newly developed protocols. However, it has not been clarified how the results from different preservation methods agrees and differ. In this study, we use a unique sample set of urinary bladder cancer tissues of two different tumor stages (Ta/T1 – non-muscle invasive and T2/T3 muscle invasive); upon sampling the tumors were divided and preserved by the two methods. Thereafter a protocol for parallel processing of the samples were applied after which the samples were analyzed with label free quantitative MS analysis. Over 700 and 1200 proteins were quantified in FFPE and OCT samples, respectively. Principal component analysis showed that the largest differences between samples are based on the preservation method, but this analysis could also classify the tumors into different stages in each preservation. The overlap of quantifiable proteins between the preservation methods were 84% when all proteins and full data set were taken into consideration, but only 41% on average when proteins from a specific tumor were analyzed. Proteins involved in mitochondrial function were overrepresented among proteins present in OCT data but missing in the FFPE data, indicating that these proteins are not well preserved by FFPE. Moreover, univariate analysis showed that HMGCS2 protein is uniquely quantified in Ta/T1 tumors in both FFPE and OCT data, and that LGALS1, ANXA5 and plastin proteins are upregulated in T2/T3 tumors compared to Ta/T1 tumors in both FFPE and OCT data, confirming the consistency between the data sets and suggesting these proteins as biomarkers. Finally, LGALS1 data were verified by immunohistochemistry staining of an independent data set.

Project description:This experiment contains the RNA-Seq samples only. Formalin-fixed, paraffin-embedded (FFPE) tissues are an invaluable resource for clinical research. However, nucleic acids extracted from FFPE tissues are fragmented and chemically modified making them challenging to use in molecular studies. We analysed 23 fresh-frozen (FF), 35 FFPE and 38 paired FF/FFPE specimens, representing six different human tissue types (bladder, prostate and colon carcinoma; liver and colon normal tissue; reactive tonsil) in order to examine the potential use of FFPE samples in next-generation sequencing (NGS) based retrospective and prospective clinical studies. Two methods for DNA and three methods for RNA extraction from FFPE tissues were compared and were found to affect nucleic acid quantity and quality. DNA and RNA from selected FFPE and paired FF/FFPE specimens were used for exome and transcriptome analysis. Preparations of DNA Exome-Seq libraries was more challenging (29.5 % success) than that of RNA-Seq libraries, presumably because of modifications to FFPE tissue-derived DNA. Libraries could still be prepared from RNA isolated from two-decade old FFPE tissues. Data were analysed using the CLC Bio Genomics Workbench and revealed systematic differences between FF and FFPE tissue-derived nucleic acid libraries. In spite of this, pairwise analysis of DNA Exome-Seq data showed concordance for 70-80 % of variants in FF and FFPE samples stored for fewer than three years. RNA-Seq data showed high correlation of expression profiles in FF/FFPE pairs (Pearson Correlations of 0.90 +/- 0.05), irrespective of storage time (up to 244 months) and tissue type. A common set of 1,494 genes was identified with expression profiles that were significantly different between paired FF and FFPE samples irrespective of tissue type. Our results are promising and suggest that NGS can be used to study FFPE specimens in both prospective and retrospective archive-based studies in which FF specimens are not available.

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Residual tissue repositories as a resource for population-based cancer proteomic studies

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Residual tissue repositories as a resource for population-based cancer proteomic studies.

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