ABSTRACT
Objectives: Breast cancer cells developing radioresistance during radiation may result in cancer recurrence and poor survival. One of the main reasons for this problem is the changes in the regulation of genes that have a key role in the epithelial-mesenchymal transition (EMT). Utilizing mesenchymal stem cells can be an effective approach to overcome therapeutic resistance. In this study, we investigated the possibility of combining mesenchymal medium with cancer cell medium in sensitizing breast carcinoma cells to radiation. Materials and Methods: In this experimental study, the cells were irradiated at a dose of 4 Gy alone and in combination with stem cells and cancer cells media. Apoptosis, cell cycle, Western blotting, and real-time PCR assays evaluated the therapeutic effects. Results: We found that the CSCM could decrease the expression of several EMT markers (CD133, CD44, Vimentin, Nanog, Snail, and Twist), resulting in increased cell distribution in the G1 and G2/M phases, apoptosis rate, and protein levels of p-Chk2 and cyclin D1; furthermore, it exhibits synergetic effects with radiation treatment in vitro. Conclusion: These findings show that CSCM inhibits the expansion of breast cancer cells and makes them more susceptible to radiotherapy, offering a unique approach to treating breast cancer by overcoming radioresistance.
ABSTRACT
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.
