EMT Variations In Carcinogenesis And Development Of Colorectal Cancer And Gene Mutations Screening

Colorectal cancer is the third leading malignancies around the world.The list of mortality followed the morbidity closely.As we know,however,the procedure of colorectal cancer is a long long way to go,showing distinct characters at each stage.This is also the result of accumulation of many pro and con factors participated in this process.Colorectal mucosa usually undergoes some characteristic stages to develop into cancer.They are hyperplasia,atypical hyperplasia,dysplasia and carcinogenesis.Specifically,they are polyp,adenoma low grade,adenoma high grade and carcinoma.The mutation of APC is considered as the initial factor in promoting the progression of colorectal tumor.The homozygotic loss of APC results in accumulation of β-catenin in cytoplasm,because of dysfunction APC degeneration system.The close relationship of APC and colorectal adenoma has been proved,and we can observed APC mutation in most adenoma samples.The accumulated β-catenin will move into nuclear,where it forms complex with TCF4 and trigger a lot of downstream genes,result in activation of Wnt pathway.Other participate mutated genes include Kras,P53 and DCC etc.The mechanism underneath colorectal cancer is the hotspot currently,the scientists are curious about what is the driving force of colorectal cancer and which factors master the progression of colorectal tumor?Epithelial-mesenchymal transition(EMT)was first observed and described by Elisabeth in chick embryos in 1980s.Since then,the study of EMT has been widely spread.EMT means epithelial cells lose their own phenotypes and acquire mesenchymal ones which enable them to move from one place to another.This character endows them ability to the development of embryo,wound healing and invasion and metastasis of many malignant tumor.In general,there are three types of EMT:type one is EMT in development of embryo;type two is EMT in wound healing and organ fibrosis;type three is EMT in invasion and metastasis of malignancies.These EMTs have similar but distinct regulation pathways.Type three get more and more attention from scientists because of great profits.As the most common disease in digestive system,revealing the mechanism under colorectal tumor is in urgent need.And the relationship between EMT and colorectal tumor has been intensely studied.In 2012,Rhim etc reported that they found EMT and dissemination precede pancreatic tumor formation by specifically tagging pancreatic epithelial and tracing the path from normal to carcinoma.They detected activation of EMT transcription factors in grade II intraepithelial neoplasia and pancreatic epithelial in liver.This provided a good opportunity for study of colorectal cancer,because it has characteristic stages on the path to evolve into carcinoma.Does EMT exist in the whole process of colorectal tumor?Does it vary along the progression stages?Which genes altered in the development of colorectal cancer?Did they play a vital role in this process?So the aim of this study are:To observe EMT phenomenon in development process of colorectal cancer and to screen mutated genes in colorectal cancer and analyse the mechanism behind these phenomenon.1.EMT alterations in carcinogenesis and development of colorectal cancerWe stained and observed EMT markers in 102 cases of adenoma low grade,105 cases of adenoma high grade and 69 cases of colon mucosa,71 cases of primary and metastasis carcinoma of colon by immunohistochemistry.The level of EMT fluctuated with the development of colorectal tumor.That was epithelial markers step down with the progression of colon tumor,while mesenchymal markers went up on the contrary.Which gave us a hint that EMT existed in the progression of colorectal cancer.When tumor progressed into carcinoma,the heterogeneity inside tumor showed different histological structure and abilities in biochemical behavior.So we divided primary and metastasis lesions into three parts:central part,invasion front(junctional zone)and tumor budding(disseminating tumor cells).The expression of EMT gradually went up with direction from central to front(junctional zone)to tumor budding(disseminating tumor cells).But the average level of EMT in hepatic metastasis was lower than in primary carcinoma of colon.Which implied that EMT varied in different stages and parts of tumor,and this difference closely related with the progression of tumor.2.The epigenetic alteration and gene mutations screening in colorectal cancer developmentWe will study alterations in epigenetic and genome to find regulation mechanisms behind EMT in development of colorectal tumor.We detected DNA methylation and hydromethylation level in colorectal mucosa,primary and metastasis carcinoma samples and found that the level of DNA methylation increased from mucosa to primay and metastasis carcinoma,but the level of DNA hydromethylation decreased on the contrary.In hepatic metastasis,DNA methylation level had significance relation with lymph node metastasis,DNA hydromethylatin level significantly related with gender;in colorectal primary carcinoma,DNA hydromethylation level closely related with gender,histological grade and prognosis.The higher the DNA hydromethylation level,the better the prognosis.The expression of EMT markers E-cadherin in mucosa had significant relationship with DNA hydromethylation,and β-catenin membrane staining in primary and metastasis of colon carcinoma had significance with DNA methylation hydromethylation.Besides,we also detected microsatellite instability in colorectal cancer tissues and found only one microsatellite instability,others were microsatellite stability.Last,we detected DNA Exome sequencing in colorectal cancers,and found the most common alteration focused on cellular metabolism and motility.We found a common channel that was ECM-receptor interaction which closely related with the development of clolorectal cancer by channel enrichment.Taking together all dasta,we draw the following conclusions:1.EMT exists the whole stages of colorectal cancer and varies with specific time and space of colorectal tumor,indicating that EMT played a dominant role in development of colorectal cancer.And this might help in detecting early stage of tumor and risk judgement.2.In colorectal primary carcinoma,the higher level of hydromethylation,the better prognosis the patients have.This could be treated as a prognosis parameter.3.The mutations of colorectal cancer genes were focused on metabolism and infiltration of cell,this might played a role in the regulation of EMT and had close relationship with metastasis of colorectal cancer.