title: [Analysis of lung metastasis using a transplantable stomach cancer of the rat--establishment of a new animal model of spontaneous metastasis].
abstract: To clarify the mechanism of cancer metastasis, new animal model of the spontaneous metastasis was established. A spontaneously metastasized lung tumor from an intraperitoneally inoculated rat stomach cancer, which was induced from a single clone, was inoculated subcutaneously in the syngeneic rats. Tumors produced again in the lung were passed subcutaneously to produce a variant with high metastatic potential. The number of the spontaneously metastasized foci of the lung from subcutaneously inoculated tumor line with high metastatic potential was 20 times more than that of a control line. This difference of metastatic potential is independent of the tumor volume at a primary site, and can not be ascribed to the process after the arrest of tumor cells in the pulmonary capillary bed, but to that of the invasion into the vessel at the primary site. Considering that the parent cell line used in this experiment had already been cloned, our result seemed to indicate that the adaptation of tumor cells to the biological environment enhanced the metastatic potential, i.e., the metastatic potential is modulated by an epigenetic change.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D008175:Lung Neoplasms / Q000556:secondary; D008297:Male; D009362:Neoplasm Metastasis / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013274:Stomach Neoplasms / Q000473:pathology