An
acinar cell carcinoma of the pancreas, which was induced in a male Wistar rat by repeated
injections of
azaserine, was propagated in cell culture. Sheets of epithelial-like cells grew within 2 weeks and were subcultured serially. Initially
acinar cell carcinoma in the culture medium produced a high level of
amylase, but the secretion ceased rapidly as cells began to proliferate. Only negligible amounts of
trypsinogen and
chymotrypsinogen were detected in cell homogenates at passages 7 and 9. The chromosome distribution ranged from hypodiploid to hypertetraploid. When cultured cells were transplanted s.c. into nude mice, palpable
tumors appeared within 4 weeks and could be transplanted serially. Histological examination of the
tumor showed poorly differentiated
carcinoma without acinar structures.
Tumor homogenate contained
amylase,
trypsinogen, and
chymotrypsinogen, and the electron microscopic examination revealed that many
tumor cells contained
zymogen-like granules. These results indicate that pancreatic
acinar cell carcinoma in cell cultures, in which there was no differentiated function, can be activated to synthesize tissue-specific
enzymes when transplanted into nude mice by yet undefined factors present in the host animals. The cell line and transplantable
tumors of pancreatic
acinar cell carcinoma may be useful in the analysis of the
biological behavior of this type of
tumor and in the study of the control mechanisms of the synthesis of tissue-specific products in cells.