The Study Of Colorectal Cancer Epithelial-mesenchymal Transition Induced By FoxA1Silencing

BackgroundColorectal cancer is one of the common malignant tumors in China which showed a rising incidence of death. It is the fourth rank of cancer death and five-year survival rate is hovering around50-60%. So far the mechanisms of invasion and metastasis of colorectal cancer need to be further studied and clarifing the mechanism of invasion, metastasis and recurrence colorectal cancer is the basis for effective treatment,which is so important to improves the quality of colorectal cancer patients’s life. Pioneer factor FoxAlis a member of transcriptional factor Fox A family. It promotes the transcription of target genes by binding the target genes with the promoters or enhancers after nucleosomes structural rearrangements. The study of FoxA1on tumors are not so much, and there are still no articles beening published in terms of colorectal cancer.ObjectiveOn the basis of previous studies, we proposed to the study FoxAl expression levels in colorectal cancer cells and anlysed microarray analysis of gene expression profiling after FoxAl silencing in colorectal cancer which can help find new biological markers and provide a basis for targeted therapy.Methods1. FoxAl expression levels were analysed in colorectal clinical samples by immunohistochemistry.2. We compared expression of EMT-related genes between FoxAl silencing SW620cells and normal SW620cells by Western Blotting.3. We extracted mRNA of FoxAl silencing SW620cells and normal SW620cells to do microarray analysis4. Results of microarray analysis were analysed by GO analysis, pathway analysis and network analysis in tools like DAVID and atBIONET.Results1. FoxAl was strongly expressed in epithelial cells of31cases of colorectal cancers while in epithelial cells of newborned glands and cutting edge of the tumor FoxAl expression levels were decreased and stromal cells do not express FoxAl.2. We found FoxAl silenced colorectal cancer cells decreased the expression of E-cadherin and increased expression of vimentin, while in transiently FoxAl overexpressed293T cells Slug and Snail expression levels were dropped with the method of Western blot3. By the analysis of Human Genome U133Plus2.0Array gene chip,1469genes were differentially expressed between FoxAl silencing cells and control cells, in which666genes were upregulated and803genes were downregulated.4. GO analysis showed that the annotation of differentially expressed genes were primarily focused on the biological regulation, development; pathway analysis showed that signaling pathways the differentially expressed genes involved were mainly tumor-associated signaling pathways, focal adhesion signaling pathway, insulin signaling pathways and so on;gene interaction network analysis of differentially expressed genes predicted potential molecular markers such as DKK1, RAC2and soConclusion1. Some colorectal caner cells do not express FoxAl and it is likely to related with epithelial-mesenchymal transition. 2. In colorectal cancer cells FoxAl silencing promotes EMT.3.Bioinformatic analysis found that FoxAl is involved in the process of cell adhension, development and DNA binding; FoxAl is involved in cancer related pathways, focal adhension pathway and insulin signaling pathway; FOXA1induced EMT may be mediated by regulating the expression of these differential expression genes.