Association study of miR-22 and miR-335 expression levels and G2 assay related inherent radiosensitivity in peripheral blood of ductal carcinoma breast cancer patients.

Identifying patient's cellular radiosensitivity before radiotherapy (RT) in breast cancer (BC) patients allows proper alternations in routinely used treatment programs and reduces the adverse side effects in exposed patients. This study was conducted on blood samples taken from 60 women diagnosed with Invasive Ductal Carcinoma (IDC) BC (mean age: 47 ± 9.93) and 30 healthy women (mean age: 44.43 ± 6.7). The standard G2 assay was performed to predict cellular radiosensitivity. To investigate miR-22 and miR-335 expression levels in peripheral blood mononuclear cells (PBMCs), qPCR was performed. The sensitivity and specificity of the mentioned miRNAs were assessed by plotting the Receiver Operating Characteristic (ROC) curve. Binary logistic regression was performed to identify the miRNA involvement in BC and cellular radiosensitivity (CR) of BC patients. The frequency of spontaneous and radiation-induced chromatid breaks (CBs) was significantly different between control and patient groups (p < 0.05). A cut-off value was determined to differentiate the patients with and without cellular radiosensitivity. miR-22 and miR-335 were significantly downregulated in BC patients. miRNAs expression levels were directly associated with CR. ROC curve assessment identified that both miRNAs had acceptable specificity and sensitivity in the prediction of BC and CR of BC patients. Binary logistic regression showed that both miRNAs could also predict BC successfully. Although only miR-22 was shown potent to predict CR of BC patients, both miR-22 and miR-335 might act as a tumor suppressor miRNAs in BC. miR-22 and miR-335 may be promising potential biomarkers in BC prediction along with other important biomarkers. Moreover, mir-22 might be a potential biomarker for the prediction of CR in BC patients.