Establishment and characterization of a new transplantable pancreatic cancer xenograft (PZX-5) in immunosuppressed mice.

Conclusion: A new, stable, transplantable human pancreatic cancer xenograft (PZX-5) model has been established in CBA immunosuppressed mice.

Background: Numerous human pancreatic carcinomas have been successfully transplanted into athymic nude mice. However, artificially immunosuppressed animals have rarely been used as recipients. Because this model system proved to be reliable for hosting many human malignancies at our institute, successive xenotransplantations of a ductal adenocarcinoma have been carried out.

Method: Immunosuppression of CBA/CA mice was achieved by thymectomy, whole-body irradiation and bone-marrow reconstruction. Tumor fragments were subcutaneously implanted from a well/moderately differentiated ductal pancreatic adenocarcinoma and serially transplanted for more than 20 mo. The xenografted tumors were characterized using morphological, immunohistochemical, biochemical, and flow cytometric methods.

Results: During the serial transplantations, the neoplasm maintained its original morphological-pathobiological characteristics. It produced a large amount of mucin and expressed carcinoembryonic antigen (CEA). Neither the mitotic activity nor the degree of differentiation was altered, and CEA was permanently detected. Flow cytometric 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 was evidenced by LDH-isoenzyme electrophoresis. The results indicate that the thymectomized--whole-body irradiated--bone-marrow reconstructed immunosuppressed mice are also appropriate hosts for pancreatic cancer xenografts.