International Journal of Medical Laboratory

en Significant Impact of let-7d MicroRNA on Breast Cancer Cell Lines Post-Radiation Treatment ژنتیک/ بیوتکنولوژی Genetics/ Biotechnology پژوهشي Research <div style="text-align: justify;">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-7d, 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-231 and MCF-7 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-7d miRNA expression changes were calculated with real-time quantitative reverse transcription polymerase chain reaction. Results: The results implied that radiation caused increased let-7d expression in breast cancer cell lines after radiation treatment. In addition, the results showed that 24 h after radiation, the expression of let-7d in the radioresistant cell line was higher than the radiosensitive one; 48 h after radiation, the expression of let-7d in the radiosensitive cell line was higher than the other one. Conclusions: The results demonstrated that radiation treatment increased let-7d miRNA expression in both radiosensitive and radio-resistant breast cancer cell lines. Therefore, let-7d might be involved in the radiosensitivity of breast cancer.</div> Breast Cancer, DNA Repair, MiRNA, Let-7d, Radio Resistance, Radiosensitivity 64 71 http://ijml.ssu.ac.ir/browse.php?a_code=A-10-516-1&slc_lang=en&sid=1 Mahdieh Nejadtaghi مهدیه نژادتقی mahdiehnejadtaghi@gmail.com 0000-0001-8919-2149 No Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Hossein Mozdarani حسین مزدارانی mozdarah@modares.ac.ir 0000-0002-2080-3287 Yes Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran