CRISPR/Cas9 mediated knocking out of OPN gene enhances radiosensitivity in MDA-MB-231 breast cancer cell line.

Purpose: Although chemotherapy and radiotherapy in conjunction with surgery have been known as the standard methods for patients with breast cancer, they frequently face resistance due to the failure of cells to death. Accordingly, improving the results requires discovering novel therapeutic approaches based on the changes in the molecular biology of cancer cells. Osteopontin (OPN) is a secreted protein that previous studies have shown to be associated with progression, poor prognosis, and metastasis in breast cancer. The current study examined the synergistic effects of radiotherapy and knocking out of OPN gene, utilizing CRISPR/Cas9 technique in MDA-MB-231 breast cancer cells.

Methods: We used to knock out the OPN gene by the two different gRNAs. The cells irradiated 24 h after transfection. The mRNA expression, tumor cell proliferation, cell cycle distribution, growth, and apoptosis were measured. Moreover, activation of Chk1 and AKT were measured via western blot.

Results: We demonstrated the OPN knocking out along with radiation led to the promotion of apoptosis, suppression of downstream genes, reduction of cell viability, and inhibition of cell-cycle progression. The western blot analysis has indicated that the knocking out of the OPN gene along with radiotherapy changes DNA damage responses substantially.

Conclusions: The OPN gene knocking out with radiotherapy might be an efficient approach to overcome the radioresistance in breast cancer.