ISSN: 2642-6145
Authors: Faraji G*
Background: Breast cancer treatment has always been an important challenge in medicine. Recent studies have revealed the importance of microRNAs miR-99b-5p and miR-100-5p in breast cancer treatment. Moreover, however not fully understood, the impact of exosomal microRNAs in human cancer progress or inhibition has been highlighted yet. The present study aimed to investigate the effects of one of the most prescribed drugs in breast cancer chemotherapy, tamoxifen, on expression level of miR-99b- 5p, miR-100-5p and also mTOR gene in MCF-7 cell lines. Methods: MCF-7 cells were treated with 30 μM tamoxifen while being in a 70% surface density, then the expression level of mentioned microRNAs and mTOR gene were investigated in RNA extracts of the cells and their exosomes. Results: Results indicated the presence of a significant increase (P <0.01) in both miR-99b-5p and miR- 100-5p expression levels in cell lines following tamoxifen treatment. Also, the evaluation of mTOR gene expression in the same cells after treatment with tamoxifen showed significant (P <0.05) expression reduction. Conclusions: Interestingly, the decrease in mTOR expression level was completely consistent with increase in the expression of exosomal microRNAs level, which seems to be reasonable considering the targeting of the mTOR gene by the two mentioned microRNAs. The results of this study suggest that the therapeutic effects of tamoxifen on breast cancer cells, can be justified not only by its direct effect on cancer cells, but also by indirect impact on elements like microRNAs expression.
Keywords: Breast Cancer; MCF-7; miR-99b-5p; miR-100-5p; mTOR; Tamoxifen
