Reliability of Tissue Microarrays in Detecting Protein Expression and Gene Amplification in Breast Cancer

Abstract

Tissue microarrays allow high throughput molecular profiling of diagnostic or predictive markers in cancer specimens and rapid validation of novel potential candidates identified from genomic and proteomic analyses in a large number of tumor samples. To validate the use of tissue microarray technology for all the main biomarkers routinely used to decide breast cancer prognostication and postsurgical adjuvant therapy, we constructed a tissue microarray from 97 breast tumors, with a single 0.6 mm core per specimen. Immunostaining of tissue microarray sections and conventional full sections of each tumor were performed using wellcharacterized prognostic markers (estrogen receptor ER, progesterone receptor PR and c-erbB2). The full section versus tissue microarray concordance for these stains was 97% for ER, 98% for PR, and 97% for c-erbB2, respectively, with a strong statistical association (kappa value more than 0.90). Fluorescence in situ hybridization analysis for HER-2/ neu gene amplification from the single-core tissue microarray was technically successful in about 90% (87/97) of the cases, with a concordance of 95% compared with parallel analyses with the full sections. The correlation with other pathological parameters was not significantly different between full-section and array-based results. It is concluded that the constructed tissue microarray with a single core per specimen ensures full biological representativeness to identify the associations between biomarkers and clinicopathological parameters, with no significant associated sampling bias. Both genetic and environmental factors play a key role in the development of breast cancer, one of the commonest cancers in the world. Understanding the basis of tumor development and progression, and identifying biomarkers for assessment of prognosis and prediction of therapy outcome are integral parts of current research efforts. Traditionally, three wellcharacterized biomarkers-estrogen receptor or ER (1-4), progesterone receptor or PR (3, 4), and c-erbB2 or HER-2/neu oncogene (5-7)-have been used in the clinical analysis of breast cancer by immunohistochemistry and fluorescence in situ hybridization (FISH), both applied to full sections of formalin-fixed, paraffin-embedded tumor tissues. However, this would be time-consuming and tedious when processing large numbers of tumors or when screening with multiple markers. The recently developed tissue microarray, composed from multiple donor tumors systematically aligned within a single recipient block, allows for high throughput molecular profiling of many tumor tissues simultaneously in a single experiment. Thin sections cut from such tissue microarray blocks can be used to study gene amplification and protein overexpression by DNA and RNA in situ hybridization or by immunohistochemistry, with tremendous savings in analysis time, labor and reagent costs. This technology has the potential to significantly accelerate studies seeking for the association between molecular changes and clinical endpoints (8, 9) and th...

Tissue microarrays characterise the clinical significance of a VEGF-A protein expression signature in gastrointestinal stromal tumours

“…The concordance between TMA and full sections, tested for five antibodies (Table 5) ranged from 92 -100% in five of six antibodies, excluding S100 (71%), in concordance with previous published results (Zhang et al, 2003a).…”

“…After case review for diagnostic confirmation, the TMA was constructed as reported elsewhere (Zhang et al, 2003a;Salto-Tellez et al, 2004). The 22 antibodies used are 34 BE12, AE 1/3, Bcl-2, CAM 5.2, CD10, CD117, CD34, c-erbB2, CK7, CK20, Desmin, Flk-1, Flt-1, Hep Par1, Ki-67, MNF 116, p53, PCNA, S100, SMA, VEGF-A and Vimentin.…”

p53 and c-kit (CD117) protein expression as prognostic indicators in breast phyllodes tumors: a tissue microarray study

“…Previous reports reviewing the accuracy and reliability of tissue microarray vs standard sections on breast cancers have concluded that results derived from tissue microarrays are representative. 34,35 In this current study, when cases constructed in duplicate, triplicate and more microarray cores were compared, 85 and 92% of cases revealed agreement of p53 and CD117 immunohistochemical findings, respectively, when positive vs negative immunostaining of stromal cells was evaluated. We compared only stromal immunostaining as this was the cellular component under main scrutiny in these tumors.…”

Expression of aquaporins and PAX-2 compared to CD10 and cytokeratin 7 in renal neoplasms: a tissue microarray study

“…In this study, we examined 202 renal neoplasms, including renal cell carcinomas, as well as oncocytomas, using immunohistochemistry and tissue microarray technology which is a useful tool for efficient and rapid analysis of protein expression by immunohistochemistry. [8][9][10] Materials and methods…”