ObjectiveTo study the mechanism of the effect on invasion and metastasis of colorectal cancer by down-regulating c-Met gene.Methodsc-Met genes were knocked down in SW480 cells, differential genes were screened by gene chip, functional cluster analysis of differential genes was carried out, and IPA was used to analyze the interaction network of cell signal pathway and related differential genes, as well as the ralationship between related genes and upstream regulatory molecules. The related genes in the suppressed signal pathway were selected for qPCR verification.ResultsAfter knockdown of c-Met, the number of up-regulated genes and down-regulated genes in SW480 cells was 399 and 286, respectively. Cluster analysis showed that c-Met knockdown had a great effect on the gene expression level of SW480 cells, IPA pathway analysis showed that HGF signaling pathway was suppressed, and after c-Met knockdown, IPA interaction network suggested that AKT2, PIK3CA, and MAP2K4 in HGF pathway were down-regulated, and qPCR verified that the above genes were also down-regulated, which was consistent with the results of microarray.Conclusionc-Met may affect the invasion and metastasis of colorectal cancer through the regulation of AKT2, PIK3CA, and MAP2K4 in HGF pathway.
Objective To identify the expression of pleiotrophin （PTN） mRNA and protein in the colorectal cancer tissues， and to explore the clinical value of it. Methods The expressions of PTN mRNA and protein in colorectal cancer tissues （colorectal cancer group） as well as normal colorectal tissues （normal control group） were tested by using in-situ hybridization and immunohistochemistry. Results The positive rates of PTN mRNA 〔63.9% （53/83） vs. 40.7%（22/54）〕 and protein〔60.2%（50/83） vs. 33.3%（18/54）〕 in colorectal cancer group were all significantly higher than those of normal control group （P=0.008， P=0.002）. There were no significant relationship between expressions of PTN mRNA and protein with gender， age， and type of tumor （P＞0.05）， but in tissues of Ⅲ-Ⅳ stage and poor differentiation，the positive rates of PTN mRNA and protein were all higher （P＜0.05）. Conclusions The over expressions of PTN mRNA and protein in colorectal cancer tissues may directly related to the invasion and metastasis. Meanwhile， it can be used as an index to predict metastasis and prognosis of colorectal cancer.
Objective To investigate effect of hepatocyte growth factor (HGF) after lentivirus-mediated RNA interference (RNAi) targeting c-Met on invasion of colonic carcinoma cell line SW480. Methods The experiment was assigned into 3 groups: NC group, the normal cells were infected by the shRNA negative control virus (the NC-20 andNC-40 represented the negative group which were added 20 ng/mL and 40 ng/mL respectively HGF after being infected); KD group, the normal cells were infected by the shRNA-c-Met target virus (the KD-20 and KD-40 represented the interfered group which were added 20 ng/mL and 40 ng/mL HGF respectively after being infected; KD1, KD2, KD3, and KD4 represented the different RNAi targets for the purpose gene); CON group, the normal cells were not infected by any virus. The lentiviral vector shRNA-c-Met was constructed and verified by polymerase chain reaction (PCR) and DNA sequencing. The SW480 cells were infected with the shRNA-c-Met after packed with lentivirus plasmid. Fourty-eight hours transfection later, the c-Met mRNA of the transfected SW480 cell was detected by real time PCR and the c-Met protein was examined by Western blot. Seventy-two hours after transfection, the cell apoptosis was detected by flow cytometry and the invasions in the different cells with stable transfection were detected by Transwell test. Results The RNAi sequence targeting c-Met gene was successfully inserted into the lentiviral vector. The shRNA-c-Met transfection resulted in an obviously reduced expression of c-Met mRNA in the SW480 cells. The efficency of gene knock down of the KD4 (the cells with No.4 target spot knocked down) was 81.4%. The shRNA-c-Met tansfection resulted in an obviously reduced expression of c-Met protein in the SW480 cells. After transfection, the apoptosis rate of the KD group was significantly higher than that in the NC group (P<0.001) or the CON group (P<0.001). The invasion ratios in the NC group, NC-20 group, and NC-40 group were significantly higher than those in the KD group (P<0.001), KD-20 group (P=0.015), and KD-40 group (P=0.017), respectively; which in the NC-20 group and NC-40 group were increased as compared with the NC group (P<0.001,P<0.001), and in the NC-40 group was increased as compared with the NC-20 group (P=0.005). The invasion ratios in the KD-20 group and KD-40 group were increased as compared with the KD group (P<0.001,P<0.001), and in the KD-40 group was increased as compared with the KD-20 group (P=0.014). Conclusion Lentivirus-mediated RNAi targeting c-Met could effectively suppress expression of c-Met in SW480 cells and could reduce invasion of HGF on SW480 cells with knocked down c-Met.
Objective To detect expression of Ras association domain family 1A （RASSF1A） gene in the colonic carcinoma tissue and to analyze the relationship of this expression to its clinical features. Methods Immunohistochemistry and Western blot methods were employed for detecting the RASSF1A protein expressions in 34 colonic carcinoma tissues and corresponding normal colon tissues. RT-PCR was employed for detecting RASSF1A mRNA expression. Results ①The RASSF1A protein expression in the colonic carcinoma tissues was significantly lower than that in the normal colontissues by using immunohistochemistry〔35.3% （12/34） versus 97.1% （33/34）， P＜0.05〕.There were significant relati-onships of RASSF1A protein expressions to the tumor differentiation and TNM stage （P＜0.05）， in other words， the positive rates of RASSF1A protein in the moderately and well differentiated andⅠ＋Ⅱof TNM colonic carcinoma tissues were all higher （P＜0.05）. ② The RASSF1A protein expression in the colonic carcinoma tissues was significantly lower than that in the normal colon tissues by using Western blot 〔0.316 8±0.019 6 versus 0.914 4±0.177 6， P＜0.05〕， which was close to the result of RT-PCR〔0.158 9±0.223 7 versus 0.572 3±0.193 9， P＜0.05〕. Conclusions Absentexpre-ssion of RASSF1A gene in the colonic carcinoma tissue might play an important role in tumor genesis and tumor progre-ssion， and it might become useful early detection of the colonic carcinoma.