| Breast cancer is one of the most common human cancer. The incidence of breast cancer is the second in women cancer. In recent year, Micro RNA-506(mi R506) is recognized as one of the many typrs fo noncodign small RNAs families, and plays an importmant role in many kinds of cancer development. The expresion of mi R506 in cancer is upregulated or downregulated. However, the mechanism of mi R506 played in breast cancer still has not been well characterized. It has been reported that the expression of IQGAP1 in tumor issum or tumor cell is upregulated. IQGAP1 can bind to many protein molecule in some signaling pathways and play the role as. carcinogenic factor. However, the mechanism of IQGAP1 in breast cancer has not been clear.1. The expression of mi R-506 was downregulated in human breast tumur tissues and breast cancer cellsFirstly, in this paper we detected the expression of mi R-506 in human breast tumur tissues by RT-q PCR assay. The results showed that the expression of mi R-506 was downregulated in human breast tumur tissues. Next, the mi R-506 expression in different phase breast cancer was detected by RT-q PCR assay. The results showed that the expression of mi R-506 was lower when the cancer phase was increased. Last, mi R-506 expression in T47 D, MDA-MB-231, MCF7, SK-BR-3 and HCC1937 cells was detected by RT-q PCR. The results showed that the expression of mi R-506 was reduced significantly, and the expression was the least in MDA-MB-231 cells.2. IQGAP1 expression in human breast tumur tissues and breast cancer cells was increasedIQGAP1 expression in human breast tumur tissues was detected by western blot. The results showed that the expression of IQGAP1 was increased significantly. Next, IQGAP1 expression in T47 D, MDA-MB-231, MCF7, SK-BR-3 and HCC1937 cells was detected by western blot. The results showed that the expression of mi R-506 was increased significantly, and the expression was the most in MDA-MB-231 cells.3. mi R-506 inhibited the the proliferation and migation of MDA-MB-231 cells and HCC1937 cellsTo verify the effect of mi R-506 on the proliferation and migation of breast cancer cells, we transfected mi R-506 mimics into MDA-MB-231 cells to make mi R-506 over expression. And then we transfected mi R-506 inhibitor into HCC1937 cells cells to make mi R-506 not expression. The proliferation and migation of MDA-MB-231 cells and HCC1937 cells were examined by MTT and transwell assay. The results showed that the proliferation and migation of MDA-MB-231 cells was reduced and the proliferation and migation of HCC1937 cells was increased. The results indicated that mi R-506 inhibited the the proliferation and migation of MDA-MB-231 cells and HCC1937 cells.4. mi R-506 targeted with IQGAP1 via 3’UTR and downregulated IQGAP1 expressionTo explore whether IQGAP1 was the downstream target gene of mi R-506, the Luciferase Reporter assay was used to verify this hypothesis. The results showed that mi R-506 targeted with IQGAP1 via 3’UTR, suggested that IQGAP1 was the downstream target gene of mi R-506. Next, the expression of IQGAP1 in MDA-MB-231 cells transfected with mi R-506 mimics and HCC1937 cells transfected with mi R-506 inhibitor was detected by western blots and RT-q PCR assay. The results showed that both the expressions of IQGAP1 RNA and protein were downregulated in MDAMB-231 cells, but upregulated in HCC1937 cells. The results indicated that mi R-506 downregulated the IQGAP1 expression.5. IQGAP1 inbibited the proliferation and migation of breast cancer cells induced by mi R-506To explore the effect of IQGAP1 in MDA-MB-231 cells transfected with mi R-506 mimics and HCC1937 cells transfected with mi R-506 inhibitor, the MDA-MB-231 cells were transfected into mi R-506 mimics and IQGAP1-pc DNA3.1 to upregulate IQGAP1 expression. And HCC1937 cells were transfected into mi R-506 inhibitor and IQGAP1 sh RNA to downregulate IQGAP1 expression. The proliferation and migation of MDA-MB-231 cells and HCC1937 cells were examined by MTT and transwell assay. The results showed that IQGAP1 over expression could inhibit the downregulated proliferation and migation of MDA-MB-231 cells induced by mi R-506 mimics. However, low level of IQGAP1 expression could inhibit the upregulatedproliferation and migation of HCC1937 cells induced by mi R-506 inhibitor. The results suggested that IQGAP1 inbibited the proliferation and migation of breast cancer cells induced by mi R-506.6. mi R-506 downregulated B-Raf expression and Erk1/2 phosphorylationTo further explore the mechanism of mi R-506 in breast cancer, the B-Raf expression and Erk1/2 phosphorylation in MDA-MB-231 cells transfected with mi R-506 mimics and HCC1937 cells transfected with mi R-506 inhibitor were detected by western blot. The results showed that the B-Raf expression and Erk1/2 phosphorylation in MDA-MB-231 cells were downregulated, but upregulated in HCC1937 cells.7. IQGAP1 inhibited the effect of mi R-506 on B-Raf expression and Erk1/2 phosphorylationTo further explore the effect of IQGAP1 on mi R-506 B-Raf expression and Erk1/2 phosphorylation, B-Raf expression and Erk1/2 phosphorylation were examined. The results showed that the downregulated B-Raf and pho-Erk1/2 expressions in MDA-MB-231 cells were recovered when IQGAP1 was over expressed. However, when IQGAP1 was not expressed, the upregulated B-Raf and pho-Erk1/2 expressions in HCC1937 cells were inhibited.Collectively, our research found that mi R-506 inhibited the proliferation and migration. Moreover, mi R-506 inhibited the expession of IQGAP1, and then inhibited ERK sgnaling pathway. In this paper, we firstly found that mi R-506 could inhibit the development of breast cancer and directly downrgulate the expression of IQGAP1. |
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