Characterization of two different factors chemotactic for cancer cells from tumor tissue

Two different factors chemotactic for cancer cells were extracted in pseudoglobulin fraction of rat ascites hepatoma transplanted tissue. After chromatography on Sephadex G-50 and CM-sephadex, these factors were separated by gel filtration on Sephadex G-100. The factor a was further fractionated by immunoadsorbent chromatography with goat antirat gamma-globulin antibody and then with rabbit antirat hemoglobin antibody; it was a protein with a molecular weight of about 78,000, resembling a chemotactic factor previously reported, and its activity was thermolabile. The previously undescribed factor b was also a protein with a molecular weight of about 14,000 and its activity was thermostable. Intradermal injection of these factors at low concentrations induced an extravascular migration of circulating tumor cells and formation of metastatic secondary tumors; and little difference in the in vivo effect between these factors was observed. It was thus assumed that the combined action of these two factors may be involved in malignant invasion.