Evaluation of NANOG Gene Suppression and Replacement of Let-7 in Breast Cancer Cell Line and The Effects on Stemness, Invasion and Apoptosis of Cells

Abstract

Abstract Introduction Failure and recurrence in breast cancer (BC) treatment because a significant obstacle in cancer therapy, and identification of cell population named cancer stem cells (CSCs) in the tumor can be help us to define these cells as target in novel therapeutic strategy. The goal of this research is to find a correlation between stemness and metastatic characteristics, to address whether CSCs are a potential target of therapy because of its developmental behavior and similarities with normal stem cells. Here, we focus on the expression of NANOG in breast CSCs, a key molecule in the physiological process of stem cells. Abnormally alteration in the miRNAs expression such as Let-7a has been demonstrated in several cancers, including BC. Amis: In this study, we have evaluated the NANOG inhibition by siRNA and the increase of Let-7a by miRNA mimics in breast cancer cell lines and the effects of these changes on biologic aspects like apoptosis, stemness and invasion of these cells. Material & Methods: SKBR3 cells have transfected by NANOG siRNA and Let-7a miRNA mimic by electroporation. Then, we have evaluated the effects of NANOG inhibition and the increase Let-7a on the apoptosis, invasion, migration, and stemness feature of the cells. Results: Our results showed that the inhibition of NANOG coincided with Let-7a increase contribute to significant decrease in stemness feature. There was significant decreasing in mRNA level of Oct4 (5-fold) and LIN28 (2.5-fold) compared to control cells. The invasion factors such as MMP9 showed the low levels (2.8-fold) of invasion rate after transfection the cells. The apoptosis rate of the SKBR3 cells increased after transfection (35%) compared to control cells. As well as the increase in the BAX/BCL2 ratio (6-fold) confirmed the flow cytometery analysis of apoptosis. According to the results, the difference between the siRNA and miRNA mimic groups was not significant, but the differences between transfected cells with the control cells were significant. Conclusion: Our data showed the importance of Let-7a and Nanog in cancer progression. In conclusion, these findings showed that a combination of Let-7a miRNA mimic and Nanog siRNA could be exploited as a new treatment to enhance tumorcidial strategy treatment and to improve the cancer therapy outcome. In this study, we showed that the using a combination of Let-7a increase and NANOG inhibition could possibly tumoricidal outcome.