Histopathological changes and experimental chemotherapy of TT-1 cell-induced tumor in nude mice

TT-1 cells, a cell line derived from pancreatic carcinoma in 1962, were tested in nude mice (BALB/c nu/nu) for their tumorigenicity and histopathological features following cell injection. Moreover, an experimental chemotherapy of TT-1-cell-induced tumors in nude mice and attempts of extracting TT-1 tumor-associated antigens were made. The tumorigenicity was measured by subcutaneous inoculation of TT-1 cells in the back of nude mice. The 50% tumor-producing dose (TPD50) for 3-wk and 5-wk old nude mice were 4.7 X 10(4) and 2.4 X 10(5) cells respectively. When 5 TPD50 of TT-1 cells were inoculated subcutaneously into 3-wk old mice, initially cells were found in the subcutaneous space of the inoculated site, then gradually growing into colonies which could be clearly demonstrated microscopically 6 days after inoculation, though by that time tumor was not perceivable nor palpable. Mitomycin-C and fluoro-uracil were administered 2 days after TT-1 cell inoculation. It was found that 5 doses of 8 microgram mitomycin-C and 0.25 mg fluoro-uracil administered intravenously were effective to prevent the nude mice inoculated with 5 TPD50 from tumor formation. However, if these two drugs were injected 3 weeks later, tumor growth was suppressed only by the first 4 doses of drugs but not thereafter. Immune sera were prepared by immunizing rabbits and mice with 3 M KCl extract of nude mouse-grown tumors. Nude mouse serum and subcutaneous tissue antigens were present in the tumor extract and showed strong antigenicity.