Expression Of DDX31 In Colorectal Cancer And Its Effect On Proliferation, Invasion And Migration Of Colorectal Cancer Cells

Objective: To detect the expression of DDX31 in colorectal cancer tissues and explore the effect of DDX31 on the function of colorectal cancer cells and the tumorigenicity of colorectal cancer cell line SW480 in nude mice to provide a theoretical basis for gene therapy of colorectal cancer.Methods: Part I:(1).Data were downloaded from TCGA database and Oncomine database and analyzed the expression level of DDX31 in colorectal cancer.Combined with the clinical information in the database,the correlation between the expression level of DDX31 and the prognosis of patients was analyzed;(2).Colorectal cancer patient information and tumor samples were collected,and immunohistochemical staining was performed to detect DDX31 expression levels,the correlation between DDX31 expression levels and clinical characteristics of patients was analyzed.Part II:(1).DDX31 siRNA was designed and the silencing efficiency was tested in the SW480 cell line;(2).Transfection of SW480 cell line with the highest silencing efficiency was performed,CCK-8 assay was used to detect the proliferation of SW480 cells and control cells silenced by DDX31.The apoptosis and cycle of SW480 cells were analyzed by flow cytometry.Cell invasiveness assay was used to detect the invasiveness of the two groups of cells,and the cell scratch assay was used to qualitatively determine the effect of DDX31 on the migration of colorectal cancer cells.Part III:(1).DDX31 interference gene fragment was obtained,and the lentiviral vector was constructed,further the lentivirus packaging and titer was detected.Lentivirus were used to transfect SW480 cell line,leading to stably silence DDX31 on SW480 cell line.Experiment of tumorigenicity of colorectal cancer cell line SW480 in nude mice was performed;(2).Immunohistochemical staining was used to detect the expression of Ki-67 in tumor xenografts.Results: Part I:(1).Analysis of TCGA and Oncomine database found that DDX31 expression level in colorectal cancer patients was upregulated relative to the control group,and high expression levels of DDX31 colorectal cancer patients have lower five-year survival rate;(2).We collected a total of 228 cases of colorectal cancer tissue samples,Immunohistochemical staining found that DDX31 protein levels were significantly increased in colorectal cancer tissue,and DDX31 protein levels were quantified.According to the DDX31 protein level,228 patients with rectal cancer were divided into DDX31 high expression group(107 cases)and DDX31 low expression group(121 cases).There was no significant difference in age and sex between the two groups.However,there were significant differences in the expression of DDX31 protein and clinical features such as tumor differentiation,TNM stage(depth of invasion,lymph node metastasis,etc.)between the two groups.Part II:(1).According to the sequence of DDX31,three siRNAs were designed.Among them,two siRNAs can significantly silenced the efficiency of DDX31 compared with the control group;(2).After silencing DDX31,the proliferation of SW480 cell line was slowed down,the early apoptosis increased,the proportion of S phase was significantly lower than that of the control group,and the ability of cell invasion and migration was weakened.Part III:(1).On the 23 rd day after subcutaneous inoculation,we found that the knockdown of DDX31 group significantly inhibited the growth of subcutaneous xenograft in nude mice and that the average tumor weight in the knockdown group was reduced to less than half of the control group;(2).The expression of Ki-67 protein in the silencing DDX31 group was significantly lower than that in the control group.Conclusions: This study shows that DDX31 is overexpressed in human colorectal cancer tissues and that high expression of DDX31 is associated with poor prognosis in patients.Knockdown of DDX31 can slow cell proliferation and promote tumor cell invasion and tumor cell apoptosis and migration ability.In vivo tumorigenesis experiments further show that silencing DDX31 can reduce the quality and volume of tumorigenesis.