Assessment of Topoisomerase II α Status in Breast Cancer by Quantitative PCR, Gene Expression Microarrays, Immunohistochemistry, and Fluorescence in Situ Hybridization

Abstract

Anthracyclines are frequently used for the treatment of breast cancer and topoisomerase II alpha (TOP2A) is considered to be the molecular target. Numerous studies have evaluated the predictive value of TOP2A using different methodological approaches and inconsistent results have been reported. Indeed, the correlation between techniques for the assessment of TOP2A status has not been well evaluated. In this study, we determined TOP2A status in 61 breast tumor samples by realtime PCR, DNA microarrays, immunohistochemistry (IHC), and fluorescence in situ hybridization (FISH), and then evaluated these results with clinical-pathological features and breast cancer intrinsic subtypes. First, we observed a statistical significant correlation of TOP2A gene expression between real-time PCR and microarrays (Pearson coefficient, 0.816; P < 0.001), and both predicted TOP2A IHC results fairly well (area under the curve > 0.74). In contrast, poor agreement between FISH and IHC data was observed (k: 0.134). Secondly, TOP2A expression was found significantly associated with cell proliferation, and with the highly proliferative Luminal B, Her2-enriched and Basal-like intrinsic subtypes. In conclusion, TOP2A expression in breast cancer was associated with high proliferation and aggressive tumor subtypes and appears to be independent of its amplification status. All of these features should be taken into consideration when assessing the predictive value of TOP2A for anthracycline-based chemotherapy.

Quantum dot-based immunofluorescent imaging and quantitative detection of TOP2A and prognostic value in triple-negative breast cancer

“…More specifically, highly proliferative subtypes such as triple negative, luminal B, and HER2-enriched expressed higher levels of the enzyme and are associated with poorer prognosis relative to less proliferative subtypes. 12,25 In this study, we focused on TNBC only, which excluded the heterogeneity of breast cancer.…”

“…This is consistent with other studies. 7,12,34 Romero et al 12 reported that TOP2A expression in breast cancer was associated with high proliferation and aggressive tumor subtypes. Rody et al 7 found that TOP2A expression showed a strong correlation with tumor size, grading, HER2, and Ki67 expression as well as nodal status.…”

“…This is in part due to the use of different detection methods (ie, immunohistochemistry [IHC], fluorescent in situ hybridization [FISH], and other molecular biology methods) and different cutoff thresholds for positive status, making comparisons between studies difficult. [9][10][11][12] Numerous retrospective studies have previously investigated the predictive value of TOP2A using different methods. Some of these approaches have focused on quantifying TOP2A expression, 13,14 whereas others have assessed TOP2A copy number.…”

Topoisomerase 2α status in invasive breast carcinoma – comparison of its clinical value according to immunohistochemical and fluorescence in situ hybridization methods of evaluation

“…Outcomes of results both at the level of evaluation of TOP2A as well as at the level of interpretation are extremely different [24][25][26][27][28][29][30][31][32][33]. If biology of breast carcinoma is similar around the world, then methods of TOP2A evaluation, criteria of interpretation and selection of patients are responsible for the differences [34][35][36][37][38][39][40][41]. We put emphasis on criteria of interpretation, and decided to create out own system of We found in our study that cases with positive TOP2A status measured by the IHC method for TOP2A protein presented a statistically significantly better response to therapy which included anthracyclines as one of the chemotherapeutics (AC program in our study) in neoadjuvant therapy measured by relapses (DFS).…”

Estrogen Receptor α Roles in Breast Cancer Chemoresistance

“…Several mechanisms of drug resistance have been examined. Overexpression of a membrane efflux transporter, P-glycoprotein (P-gp) (Shi et al, 2011) (Romero et al, 2011), changes in topoisomerase II activity (Romero et al, 2011), modifications in glutathione S-transferase (Romero et al, 2012), and altered expression of apoptosis-associated protein Bcl-2 (Bjerre et al, 2012;Larsen et al, 2012) and tumor suppressor protein p53 . ERα status, although lesser known, have also been studied in connection with MDR.…”