Correlation between expression of TOP2A and HER2 signaling pathway in breast cancer

Objective: To study the correlation of expression of DNA topoisomerase Ⅱ alpha (TOP2A) with expressions of human epidermal growth factor receptor 2 (HER2) and phosphatase and tensin homolog (PTEN) and gene mutation of phosphatidylinositol 3-kinase (PI3K) in breast cancer so as to provide reference for prognosis of the cancer and evaluation of drug efficiency. Methods: This study enrolled totally 96 breast cancer patients. Tumor specimens were resected. The gene expressions of TOP2A, HER2 and PTEN were analyzed using branched DNA-liquid-chip, and PI3K gene mutation was detected by xTAG-liquid-chip. Correlations between gene expressions and gene mutation were further explored by Spearman correlation analysis so as to clarify the relationship between TOP2A and HER2 signaling pathway gene. Results: Co-expression of TOP2A and HER2 was strong, and TOP2A tended to be highly expressed in the presence of high expression of HER2 (P=0.01). The expression of PTEN was not significantly correlated with the expression of TOP2A, whereas the mutation of PI3K had a positive association with the high expression of TOP2A (P=0.004). Conclusion: Anthracycline drug resistance factor TOP2A may be related to the critical factors of HER2 signaling pathway, suggesting that HER2 expression and PI3K mutation may be key factors in regulation of TOP2A expression, which would provide important evidence for chemotherapeutic resistance.