Screening And Identification Of The Molecular Markers Of Hepatic Metastasis In Colorectal Cancer

As the prevalent malignancy of alimental track,the incidence and mortality for colorectal cancer(CRC) ascended to the fourth and fifth place in China,respectively.The therapy for CRC most fails to hepatic metastasis.At present,the combination of multiple therapies plays a great role in CRC,especially surgical therapy.It's necessary to have a precise evaluation on the prognosis.However the clinical examinations can not meet with the request.Detection of the changes in the molecular level will assist in tumor therapy.Based on the hepatic colorectal metastasis model of nude mouse,the research screened the molecular biomarkers on colon adenacarcinoma metastasis through differential cDNA profiles between the high and low metastastic potential cells.Through the verification by human tissue specimens,we succeeded in uncovering a molecular marker profiles for prediction of hepatic colorectal metastasis.SW1116-P₂₁ cell line with high adhesion ability is cultured in our lab.Descendent of SW1116-P₂₁ cell line by screening in vivo,SW1116-P₂₁ cell line has a higher metastasis potential than its parent.The differential gene profile of hepatic metastasis was analyzed by comparing SW1116-P₂₁ with SW1116-P₂₁ in cDNA microarray.Through analyses of the up-regulated genes in the gene profile in vivo,a panel of 8 molecular biomarkers including LGALS3,SNCG,CCND3,SERPINE1,IQGAP1,CCL2,CYR61 and LGALS3BP,were selected for the follow-up in the clinicalpathological relevant research.One hundred and seventeen cases of advanced CRC with liver metastasis,and one hundred and four cases of advanced CRC without liver metastasis with a follow-up time for at least 5 years after resection of the primary CRC were selected.Obvious positive expressing difference was observed in CCL2 and SNCG in the analysis of 8 molecular biomarkers by immunohistochemistry(IHC).CCL2 and SNCG were all found to be significantly higher in the cases of CRC with liver metastasis than in cases of non-metastatic CRC.Then we analyzed the clinicopathological factors and the expression of the two biological factors,CCL2 and SNCG,respectively.CCL2 was associated with the gross type of CRC and TNM stage(P＜0.05),especially with lymph node metastasis (P=0.001).SNCG was associated with the T term and TNM stage(P＜0.05).In the group of synchronous liver metastasis,the median survival time of SNCG-negative was superior to SNCG-positive,12.6 months and 8.2 months respectively(Log Rank,P=0.037).By multivariate Cox's analysis,SNCG was the only independent prognostic variable(95%CI: 1.03～3.26,P=0.04).Logistic regression analysis showed that tumor diameter,T term, lymph node metastasis,the expression of CCL2 and the expression of SNCG were independent factors.If all five factors were positive,the probability of liver metastasis became 97%.The index of metastasis risks for SNCG and CCL2 are 6.99(95%CI, 3.14～15.6,P＜0.05) and 4.28(95%CI,1.92～9.52,P＜0.05),respectively.To identify the genes involved in metastasis from the gene profile of the paired tissue specimens,the cDNA microarray was used to detect differences in gene expression between colorectal tumors and paired liver metastases isolated from 6 patients.The cluster analysis revealed that 4 of 6 paired gene profiles have more similarity with each other and the others not.It can be interpreted as that commonness and individual character both exited in the gene profile of liver metastasis from colorectal cancer.Subsequent analysis of up-regulated genes showed their involvement in metabolism,transcription and proliferation.The down-regulated genes were involved in invasion,motility,adhesion, proliferation and cell differentiation.It was informed that the gene profiles from animal model and from the paired tissue specimen were completely different.So the differences in gene expression between colorectal tumors and paired liver metastases may play a role in the research on molecular targeted therapy but not in screening the metastasis biomarkers.