Circulating RP11-445H22.4 and TINCR are Potential Biomarkers for Invasive Ductal Carcinoma of the Breast

Introduction: Invasive ductal carcinoma (IDC) is a frequently observed type of breast cancer. Moreover, it has been demonstrated that long non-coding RNAs (lncRNAs) are associated with various diseases, including cancer, and they may have the potential to act as biomarkers. Methods. The relative quantitation (RQ) of two lncRNAs, RP11-445H22.4 and TINCR, was measured in tumoral tissues and paired adjacent non-tumoral tissues (PANTs) as well as in plasma samples using real-time polymerase chain reaction (RT-PCR). Furthermore, promoter methylation of the two lncRNAs genes was assessed using methylation-specific PCR (MSP). In order to compare the diagnostic values, plasma levels of CA 15-3 were measured as a conventional circulating biomarker using ELISA. The receiver operating characteristic (ROC) curve was used to illustrate the sensitivity and specificity of the potential biomarkers. Results. The RP11-445H22.4 and TINCR genes were upregulated in tumor tissues compared to PANTs (RQRP11-445H22.4 = 2.7, RQTINCR = 4.4). Furthermore, the presence of RP11-445H22.4 and TINCR in the plasma of patients was significantly more than healthy controls (RQc.RP11-445H22.4 = 4.12, RQc.TINCR = 4.16, P<0.001). The promoters of RP11-445H22.4 and TINCR genes were hypomethylated in the tumoral tissues with a negative correlation with their gene expression. Conclusion. Based on the findings, it can be speculated that the expression levels of these two lncRNAs as well as their promoter methylation can be considered as a therapeutic target and potential biomarker for breast carcinoma.