Significant Impact of let-۷d MicroRNA on Breast Cancer Cell Lines Post-Radiation Treatment

Introduction: Radiotherapy is a common treatment for breast cancer treatment, that induces DNA damage. These DNA damages are addressed through various repair pathways, which regulate the DNA repair systems and confer radio-resistance. Non-coding RNAs are a big proportion of genome transcripts without the potential to encode proteins. Related studies demonstrated that radiation affects the expression of non-coding RNAs. Let-۷d, a tumor suppressor in numerous cancers, has some target genes that play a role in the DNA repair system. Materials and Methods: Human breast cancer cell lines MDA-MB-۲۳۱ and MCF-۷ were cultured in a Dulbecco's Modified Eagle Medium. The exponentially growing cells were treated with some doses of X-rays. After radiation treatment and cell harvesting, RNA was extracted, and cDNA synthesis was done. The let-۷d miRNA expression changes were calculated with real-time quantitative reverse transcription polymerase chain reaction. Results: The results implied that radiation caused increased let-۷d expression in breast cancer cell lines after radiation treatment. In addition, the results showed that ۲۴ h after radiation, the expression of let-۷d in the radioresistant cell line was higher than the radiosensitive one; ۴۸ h after radiation, the expression of let-۷d in the radiosensitive cell line was higher than the other one. Conclusions: The results demonstrated that radiation treatment increased let-۷d miRNA expression in both radiosensitive and radio-resistant breast cancer cell lines. Therefore, let-۷d might be involved in the radiosensitivity of breast cancer.

کلیدواژه ها:

Breast Cancer ، DNA Repair ، MiRNA ، Let-۷d ، Radio Resistance ، Radiosensitivity