NIH, National Cancer Institute, Division of Cancer Treatment and Diagnosis (DCTD) NIH - National Institutes of Health National Cancer Institute DCTD - Division of Cancer Treatment and Diagnosis

Optimal Reference Genes for Normalization of qRT-PCR Data from Archival Formalin-fixed, Paraffin-embedded Breast Tumors Controlling for Tumor Cell Content and Decay of mRNA.

Author(s): Tramm T, Sørensen BS, Overgaard J, Alsner J

Publication: Diagn Mol Pathol, 2013, Vol. 22, Page 181-7

PubMed ID: 23846446 PubMed Review Paper? No

Purpose of Paper

The purpose of this paper was to determine the effects of storage duration on the expression of 16 housekeeping genes in formalin-fixed paraffin-embedded (FFPE) breast tumors by real-time qRT-PCR.

Conclusion of Paper

Expression levels of calmodulin 2 (CALM2), ribosomal protein L37a (RPL37A), beta actin (ACTB), and ribosomal protein large P0 (RPLP0) were shown to be the least variable with storage. Amplification failures increased with increasing storage duration of FFPE blocks, and even the most stably expressed transcripts showed an average increase of 0.22 per year in cycle threshold (CT) values. Importantly, normalized CT values were not affected by storage.

Studies

  1. Study Purpose

    The purpose of this study was to determine the effects of storage duration on the expression of 16 housekeeping genes in FFPE breast tumors by real-time qRT-PCR. RNA was isolated from sections of FFPE tissue using VERSANT, but the storage duration of sections and details of FFPE processing were not specified.

    Summary of Findings:

    The majority of transcripts were detected in all specimens, but beta- glucuronidase (GUSB), hydroxymethylbilane synthase (HMBS), importin 8 (IPO8), and prosome macropain 26S subunit ATPase 4 (PSMC4) were only detected in 95%, 77.5%, 97.5% and 87.5% of specimens, respectively. The real-time qRT-PCR failures occurred when using RNA isolated from 11 FFPE specimens, 8 of which had been stored for 23-29 years, while 2 were stored for 20-21 years, and 1 was stored for 7 years. Expression levels of CALM2, RPL37A, ACTB, and RPLP0 were shown to be the most stable over time, and HMBS and PSMC4 were the least stable; however, the raw CT value of even the most stably expressed transcripts increased by an average of 0.22 per year, but the normalized values were consistent. The variability in expression levels was mostly attributed to differences between specimens.

    Biospecimens
    Preservative Types
    • Formalin
    Diagnoses:
    • Neoplastic - Carcinoma
    • Neoplastic - Benign
    Platform:
    AnalyteTechnology Platform
    RNA Real-time qRT-PCR
    Pre-analytical Factors:
    ClassificationPre-analytical FactorValue(s)
    Storage Storage duration 1-29 years
    Real-time qRT-PCR Specific Targeted nucleic acid CALM2
    RPL37A
    ACTB
    RPLP0
    SF3A1
    TBP
    B2M
    PUM1
    GAPDH
    OAZ1
    MRPL19
    TFRC
    GUSB
    HMBS
    IPO8
    PSMC

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