Open Access Research article

Expression profiling of formalin-fixed paraffin-embedded primary breast tumors using cancer-specific and whole genome gene panels on the DASL® platform

Monica M Reinholz1*, Jeanette E Eckel-Passow2, S Keith Anderson2, Yan W Asmann2, Michael A Zschunke1, Ann L Oberg2, Ann E McCullough3, Amylou C Dueck4, Beiyun Chen1, Craig S April5, Eliza Wickham-Garcia5, Robert B Jenkins1, Julie M Cunningham1, Jin Jen6, Edith A Perez7, Jian-Bing Fan5 and Wilma L Lingle1

Author Affiliations

1 Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First St SW, Rochester, Minnesota, 55905, USA

2 Division of Biomedical Statistics and Informatics Mayo Clinic, 200 First St SW, Rochester, Minnesota, 55905, USA

3 Department of Pathology, Mayo Clinic, 13400 E. Shea Blvd, Scottsdale, Arizona, 85259, USA

4 Section of Biostatistics, 13400 E. Shea Blvd, Scottsdale, Arizona, 85259, USA

5 Department of Scientific Research, Illumina Inc., 9885 Towne Centre Drive, San Diego, California, 92121, USA

6 Division of Pulmonary and Critical Care Medicine, Mayo Clinic, 200 First St SW, Rochester, Minnesota, 55905, USA

7 Division of Hematology and Oncology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, Florida, 32224, USA

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BMC Medical Genomics 2010, 3:60  doi:10.1186/1755-8794-3-60

Published: 20 December 2010



The c

nnealing, extension,
election and
igation (DASL) assay has become a suitable gene expression profiling system for degraded RNA from paraffin-embedded tissue. We examined assay characteristics and the performance of the DASL 502-gene Cancer Panelv1 (1.5K) and 24,526-gene panel (24K) platforms at differentiating nine human epidermal growth factor receptor 2- positive (HER2+) and 11 HER2-negative (HER2-) paraffin-embedded breast tumors.


Bland-Altman plots and Spearman correlations evaluated intra/inter-panel agreement of normalized expression values. Unequal-variance t-statistics tested for differences in expression levels between HER2 + and HER2 - tumors. Regulatory network analysis was performed using Metacore (GeneGo Inc., St. Joseph, MI).


Technical replicate correlations ranged between 0.815-0.956 and 0.986-0.997 for the 1.5K and 24K panels, respectively. Inter-panel correlations of expression values for the common 498 genes across the two panels ranged between 0.485-0.573. Inter-panel correlations of expression values of 17 probes with base-pair sequence matches between the 1.5K and 24K panels ranged between 0.652-0.899. In both panels, erythroblastic leukemia viral oncogene homolog 2 (ERBB2) was the most differentially expressed gene between the HER2 + and HER2 - tumors and seven additional genes had p-values < 0.05 and log2 -fold changes > |0.5| in expression between HER2 + and HER2 - tumors: topoisomerase II alpha (TOP2A), cyclin a2 (CCNA2), v-fos fbj murine osteosarcoma viral oncogene homolog (FOS), wingless-type mmtv integration site family, member 5a (WNT5A), growth factor receptor-bound protein 7 (GRB7), cell division cycle 2 (CDC2), and baculoviral iap repeat-containing protein 5 (BIRC5). The top 52 discriminating probes from the 24K panel are enriched with genes belonging to the regulatory networks centered around v-myc avian myelocytomatosis viral oncogene homolog (MYC), tumor protein p53 (TP53), and estrogen receptor α (ESR1). Network analysis with a two-step extension also showed that the eight discriminating genes common to the 1.5K and 24K panels are functionally linked together through MYC, TP53, and ESR1.


The relative RNA abundance obtained from two highly differing density gene panels are correlated with eight common genes differentiating HER2 + and HER2 - breast tumors. Network analyses demonstrated biological consistency between the 1.5K and 24K gene panels.