Expression and clinical significance of microRNA-126-3p in breast carcinomas with different immunohistochemical profiling

Objective To investigate the expression of microRNA (miRNA, miR)-126-3p in breast carcinomas with four different immunohistochemical profiling and their relevance to clinicopathologic features. Methods The expression of miR-126-3p was detected by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) in 67 paired frozen breast carcinomas tissues and further detected by TMA-ISH in 140 cases of formalin fixed paraffin-embedded (FFPE) breast carcinomas tissues. Results MiR-126-3p expression level was lower in carcinoma tissues than that in paired para-cancerous tissues, and lowest in triple-negative breast cancer (TNBC) immune phenotype without significant difference using FQ-PCR method. The results of TMA-ISH showed that miR-126-3p was mainly expressed in stroma of tumor tissue, and its expression level was higher in tumor tissue than that in breast fibroadenomas (χ2=21.48, P<0.01). Triple-negative breast cancers in stroma showed the lowest miR-126-3p expression level (high expression rate of 60%), and human epidermal growth factor receptor-2 (Her-2) over-expressed group showed the highest expression level (high expression rate of 91.3%) within four subtypes, which had the significant differences (χ2=6.26; P<0.05). Furthermore, strong miR-126-3p expression was significantly associated with Her-2 expression (χ2=5.73, P<0.05). Conclusion There was a difference in the miR-126-3p expression in breast tumor between different immune phenotypes, which may be used as a potential individual diagnostic and drug target for breast cancer patients. Key words: Breast carcinoma; MicroRNA-126-3p; Human epidermal growth factor receptor-2 over-expression