The Study Of Source Of Cell-free DNA In Nude Mice Models With Human Ovarian And The Relationship Of It And Tumor Burden And Apoptosis

Objective: Circulating cfDNA (circulating cell-free DNA, cfDNA) is detectable DNA sequence fragment in plasma or serum of healthy individuals or patients. Female nude mice were injected by human EOC cell line SKOV3 to instruct nude mice models with human ovarian. Semi-quantitive PCR was used to analyze the level of the serum cfDNA. The correlation between cfDNA level in the serum or ascites and tumor volume or apoptosis were analysis. Investigate whether tumor related cfDNA correlate to tumor bear or apoptosis and its'Source in nude mice models with human ovarian.Methods: 6-8 weeks female nude mice were injected on the back and intra-abdomen by human EOC cell line SKOV3, the tumors and serum were collected on day 14, day 21 and day 30 respectively in tumor-bear group; the serum and ascites were collected on day 14 in ascites group; the mice were given cisplatin injection on day 30, the serum and tumors were collected on day 31, day 33, day 40 in chemotherapy group. We designed four primers base on the CA-125 gene sequence(261bp, 189bp, 336bp and 101bp). Semi-quantitive PCR was used to analyze the level of the serum cfDNA, including ALU247, ALU115, CA125-cfDNA andβ-actin. TUNNEL was used to detect cell in-situ apoptosis. The correlation between cfDNA level in the serum or ascites and tumor volume or apoptosis were analysis. Apply ANOVA(analysis of variance), t-test and spearman correlation of SPSS13.0 statistical software handling data.Results:1 DNA fragments of ALU247, ALU115, 101 bps fragment of CA125-cfDNA andβ-actin were found in the serum or ascites of every groups, especially the 261 bps fragment of CA125-cfDNA level was found in 41 of 80 mice (51.25%), but the 189 bps and 336 bps fragments were not found in all groups.2 Serum cf-DNA level and tumor-bear 101 bps fragment of CA125-cfDNA and tumor related cf-DNA in serum are positive correlated with tumor weight, the differences are significant in statistics(P<0.05).3 Serum cf-DNA level detection after chemotherapy101 bps fragment of CA125-cfDNA and tumor related cf-DNA in serum reach to maximal value on day 1 after chemotherapy, and then slow down, the values were significant lower on day 10 after chemotherapy than that pre-chemotherapy.4 Serum cf-DNA level and tumor cell apoptosis after chemotherapy.101 bps fragment of CA125-cfDNA and tumor related cf-DNA are positive correlated with cell apoptosis respectively. (P<0.05) Conclusion:1 Human specific cf-DNA can be found in the serum and ascites of tumor-bear nude mice, the cfDNA level increased significantly after chemotherapy and then slow down, also it correlated with cell apoptosis. Base on our results, the cf-DNA coming from tumor cell was certified, and it also correlated with apoptosis and necrosis.2 101 bps fragment of CA125-cfDNA and tumor related cf-DNA in serum positive correlated with tumor-bear, showed some useful information to EOC diagnosis and management.