Expression level of miR-155, miR-15a and miR-19a in peripheral blood of ductal carcinoma breast cancer patients: Possible bioindicators for cellular inherent radiosensitivity.

Examination of cellular radiosensitivity (RS) helps prevent the adverse side-effects of radiotherapy in radioresistant tumors. We aim to study whether miRNA-155 (miR-155), miR-19a and miR-15a can predict inherent RS according to cellular RS in breast cancer (BC) patients. This study was done on the blood samples of 40 invasive ductal carcinoma (IDC) BC patients and 15 healthy women. G2 assay was performed to evaluate cellular RS. To study the expression level of these miRNAs in blood, qRT-PCR was used. The sensitivity and specificity of the studied miRNAs were assessed by the receiver operating characteristic (ROC) curve. The yield of spontaneous (SY) and radiation-induced (RIY) chromatid breaks (CBs) was significantly different between control and patient groups (p < 0.0001). A cut-off value was specified to recognize the patients with cellular RS from those without. Expression of miR-15a was significantly downregulated (p < 0.0001) in BC patients. However, miR-19a showed upregulation in the blood of BC patients. It was also found the expression level of miR-155 and miR-19a were significantly associated with frequency of CBs (FCB) (p < 0.05). ROC curve analysis manifested that the miR-15a and miR-19a differentiate BC patients and healthy women with 0.91 and 0.68 yielding an area under the ROC curve, respectively. miR-155 and miR-19a discriminate between BC patients with and without cellular RS with area under the ROC curve 0.98 and 0.68. Our findings uncovered miR-155 and miR-19a could be applied as a bioindicator to predict cellular radiosensitivity of BC patients.