ESTABLISHMENT AND CHARACTERIZATION OF A NEW TRANSPLANTABLE PANCREATIC-CANCER XENOGRAFT (PZX-5) IN IMMUNOSUPPRESSED MICE

Conclusion, A new, stable, transplantable human pancreatic cancer xeno graft (PZX-5) model has been established in CBA immunosuppressed mice, Background, Numerous human pancreatic carcinomas have been successful ly transplanted into athymic nude mice. However, artificially immunosu ppressed animals have rarely been used as recipients. Because this mod el system proved to be reliable for hosting many human malignancies at our institute, successive xenotransplantations of a ductal adenocarci noma have been carried out. Method, Immunosuppression of CBA/CA mice w as achieved by thymectomy, whole-body irradiation and bane-marrow reco nstruction. Tumor fragments were subcutaneously implanted from a well/ moderately differentiated ductal pancreatic adenocarcinoma and seriall y transplanted for more than 20 mo. The xenografted tumors were charac terized using morphological, immunohistochemical, biochemical, and flo w cytometric methods. Results, During the serial transplantations, the neoplasm maintained its original morphological-pathobiological charac teristics. It produced a large amount of mucin and expressed carcinoem bryonic antigen (CEA). Neither the mitotic activity nor the degree of differentiation was altered, and CEA was permanently detected. Flow cy tometric DNA analysis revealed an aneuploid pattern (DNA index 1.45 +/ - 0.03), which has remained within the same range during xenograftings . The doubling time in an in vitro system proved to be 18 h. The human character has been well preserved even 9 mo posttransplantation, as w as evidenced by LDH-isoenzyme electrophoresis. The results indicate th at the thymectomized-whole-body irradiated-bone-marrow reconstructed i mmunosuppressed mice are also appropriate hosts for pancreatic cancer xenografts.