Cellular adjustment of gastric cancer for hepatic metastasis in successive orthotopic implantation model

In order to examine the mechanisms of hepatic metastasis in gastric cancer, a repeated orthotopic implantation method was used in nude mice with YCC-16, which was isolated from the blood of a gastric cancer patient. This study compared the biological and cytogenetic phenotypes of the five cell lines, the parental YCC-16, the orthotopic primary S1L0 and the 3 subsequent liver metastatic clones of S1L1, S2L2 and S3L3. E-cadherin and DAG1 gene expression levels were measured using real-time PCR. The parental YCC-16 showed multiple metastases, whereas the liver metastatic clones metastasized to the liver only. The liver metastatic rate showed increased trend with subsequent passages (passageII: 2/5, 40%; passageIII: 3/5, 60%; passageIV: 4/5, 80%). Otherwise, the liver metastatic clones had phenotype with a higher motility than that of the cell line from the orthotopic primary tumor (S1L0), and clonogenecity increased with subsequent passages in liver metastatic cell lines. The five cell lines had similar and additional chromosomal abnormalities were found in the selected clones. The E-cadherin expression level was decreased in all of the five cell lines, which was comparable to the common chromosomal changes. YCC-16 presented the lowest DAG1 expression level while S1L0 presented the highest. In the liver metastatic clones, the DAG1 expression level increased gradually with passages. Both the genetic alteration and cellular adjustment to the microenvironment are required for hepatic metastasis in gastric cancer. This model offers an opportunity to study the mechanisms of a hepatic metastasis of gastric cancer at the genetic and cellular level.