The Study For The Chemoresistance Of Colorectal Carcinoma

PartⅠSnail1 in Colorectal Cancer was Associated with Prognosis and 5-fluorouracilResistancePurpose: To investigate the expression level of Snail1 in colorectal cancer and its relationship with prognosis and chemoresistance.Materials and methods: The expression of Snail1 was detected by immunohistochemistry,and its relationship with the prognosis and chemoresistance was tested.Snail1 was then overexpressed in colorectal cancer cell line HCT116 and SW480,and its response to 5-fluorouracil treatment was studied using CCK8.Results: Immunohistochemical results showed that Snail1 expression was correlated with the prognosis,the higher the expression level,the worse the prognosis was.Also the high level of Snail1 was correlated with poor response to chemotherapy based on 5-fluorouracil.In vitro study represents that Snail1 overexpressing cell lines showed chemoresistance to 5-fluorouracil.Conclusion: Snail1 can affect the prognosis of patients with colorectal cancer and their response to 5-fluorouracil based treatment.Part Ⅱ DKK4 is Involved in Snail1-mediated Colorectal Cancer Resistance to 5-fluorouracilPurpose: To investigate whether DKK4 is involved in the chemoresistance to 5-fluorouracil induced by Snail1 in colorectal cancer.Materials and Methods: The expression of DKK4 was detected by immunohistochemistry and its relationship with Snail1 was studied.The expression of DKK4 was detected in the colorectal cancer cell line overexpressing Snail1.Si-RNA was used to knockdown DKK4 in Snail1 overexpressed cell line,and the response of these cell lines to 5-fluorouracil treatment was studied by using CCK8.Results: The results of immunohistochemistry showed that DKK4 was positivelycorrelated with the expression of Snail1 in colorectal cancer.The expression of DKK4 in colorectal cancer cell line overexpressed Snail1 was also higher than those in control group.Knocking down of DKK4 in Snail1 overexpressed cell line with specific si-RNA reversed the chemoresistance induced by Snail1.Conclusion: DKK4 plays a role in chemoresistance of 5-fluorouracil induced by Snail1 in colorectal cancer.Part Ⅲ USP53 is Downregulated in Colorectal Cancer and is Associated with ChemoresistancePurpose: To investigate the expression,prognostic value and function of USP53 in colorectal cancer.Materials and Methods: The expression of USP53 was detected in paraffin embaded and frozen samples of colorectal cancer patients.The data collected from TCGA database was to study USP53’s relationship with prognosis and chemoresistance.We overexpressed USP53 in HCT116 cell line and CCK-8 was applied to study its influence on cell proliferation.Results: The expression of USP53 in colorectal cancer was lower than that in adjacent normal tissues.TCGA data showed that the higher the expression of USP53 m RNA,the better the prognosis and the more sensitive to chemotherapy.The overexpression of USP53 in cell lines could inhibit the proliferation of USP53Conclusion: The expression of USP53 in colorectal cancer is decreased,and it is related to prognosis and therapeutic response.Part Ⅳ Establishment of the Organoids Culture SystemPurpose: To establish an organoid’s culture system of colorectal cancer in the absence of niche factors.Materials and Methods: Organoids was cultured in the absence of niche factorsand the corresponding gene expression was examined by using realtime-PCR.Immunochemistry,HE and special staining were performed to observe the morphology of orgnaoid.Results: Part of the Organoids could grow in the absence of niche factors while the others could not.The expression level of LGR5 and AXIN2 in the group with or without niche factors is dependent on its characteristic.Also,organoids may reflect the pathological types of cancer.Conclusions: Some organoids could be long-term cultured even without niche factors.