The Role Of Foxf2and Its Regulation Mechanism In Breast Cancer Metastasis

Background:Foxf2is a member of the forkhead box transcription factor family. Protein coded by this gene has a DNA binding motif with a helix-hairpin-helix structure looks like a wing in the C-terminal, which could recognize the special binding sequence AATAAACA and make a combination as a monomer, there are two transcriptional activation domain(AD)in the N-terminal. Foxf2activate transcription by cooperate with common transcription factor and basic transcription apparatus. So far, rare report has been found on the relationship between Foxf2and breast cancer. In previous study, we found its mRNA down-regulated in the lymph node metastases compared to the primary carcinoma, which suggested a potential function in breast cancer.Objective:To analyses the relation between the expression level of Foxf2mRNA and prognosis in breast cancer patients, in odor to estimate whether it could become a molecular marker in predicting the prognosis in breast cancer patients. To elucidate the mechanism of Foxf2in regulating gene expression during the process of breast cancer metastasis using a systems biology method based on previous expression profiling data. Then justify the hypothesis through experiment carrying out.Methods:Real time RT-PCR and immunohistochemistry is performing to detect the mRNA and protein expression of Foxf2in separately, hoping to find the correlation between Foxf2and prognosis of breast cancer patients and make a clarification if Foxf2has something related to any clinic or pathology factor. To predict the mechanism of Foxf2in regulating gene expression during breast cancer metastasis via the way of bioinfomatics based on previous gene expression profiling data. In the end, we want to draw a picture reflect the gene regulation network centered by Foxf2. At last, we will do some experiment on breast cancer cell lines to testify the regulation by Foxf2in breast cancer metastasis, using Western blot, immunohistochemistry and immunofluorescence techniques.Result: 1. Kaplan-Meier survive analysis tells the expression of Foxf2mRNA has strong correlation with metastasis free survive and disease free survive, P value is0.032and0.003.2. The low Foxf2mRNA expression ratio in clinic stage Ⅲ is higher than that in stage Ⅰ～Ⅱ(P=0.003), in lymph node-positive group is higher than lymph node-negative group(P=0.018), ER-negative is higher than ER-positive(P=0.016), PR-negative is higher than PR-positive(P=0.036).3. FOXF2protein seems no relationship with the prognosis or clinic pathology factors (P>0.05).4.42candidate genes out of135genes that have the coefficient correlation with Foxf2over0.5were screen as Foxf2-related genes related to ECM remodeling, including16ECM components,9degrading enzymes of ECM and their inhibitors, and17signal molecular.9genes were identified as upstream regulating genes of Foxf2without Foxf2binding sequence in their promoters and other17genes were identified as candidate genes regulated by Foxf2with one or more Foxf2binding sequence in their promoters.5. The low metastasis ability breast cancer cell line MCF-7and T47D express more FOXF2protein than MDA-MB-231S and MDA-MB-435S, which have high metastasis ability. The former express E-Cad and the later express N-Cad and Vim.Conclusion:1. The low Foxf2mRNA expression seems bad cancer processing and poor prognosis, it is a potential marker for predicting outcome in patients.2. NF-kappa B and IGF are the signal pathways initialing Foxf2expression, and Foxf2can regulate the ECM remodeling and promote the metastasis by changing the expression level of ECM components, degrading enzymes of ECM and their inhibitors, and cell signal molecules.3. FOXF2protein expression is important for the maintain of the epithelium, it probably inhibit cancer metastasis.