ABSTRACT
Breast cancer is a prevalent cancer type among women worldwide, with the second highest incidence rate. The objective of this study was to identify a non-invasive biomarker for detecting breast cancer, and to this end, miRNA clusters were investigated as potential candidates. A micro-RNA cluster located on the X chromosome q27.3 region was selected for the study. The research was conducted as a case-control study with a sample size of 100 patients with breast cancer and 100 healthy individuals. Tissue samples from breast cancer tumors and tumor margins were collected from the breast cancer patients. Following RNA extraction and RT-PCR, the expression of miRNA clusters, including miR-506, miR-507, miR-508, miR-509, miR-513, miR-888, miR-891, miR-892-a, and miR-892-b, was analyzed in the serum and breast tissue of the breast cancer patients. The expression of various micro-RNAs in the case and control serums was compared, and it was found that all mentioned micro-RNAs, except mir888-5p and mir-509-3p, exhibited significant and meaningful differences between the patients and control serum groups. These micro-RNAs can be considered as potential tumor markers with a confidence level of P-value = 0.0001. In contrast, mir888-5p and mir-509-3p were considered non-significant. The expression of all micro-RNAs in the tumor margin and BC tumor was significant with a P-value < 0.0001. Based on the ROC curves, all the mentioned microRNAs, except mir-888-5p, mir-513-a-5p, and mir-509-3p, exhibited high sensitivity and specificity and can be considered remarkable non-invasive tumor markers for breast cancer detection.