In vitro pancreatic ductal cell carcinogenesis

Our experiments were designed to identify initial biochemical and biological changes that occur during pancreatic carcinogenesis. TAKA‐1, an immortal hamster pancreatic ductal cell line, was treated in vitro for up to 11 weeks with the pancreatic carcinogen N‐nitorosobis(2‐oxopropyl)amine (BOP). These treated cells were designated TAKA‐1 + BOP. The growth of TAKA‐1 and TAKA‐1 + BOP cell lines was investigated in soft agar and in hamsters intradermally. The resulting tumor from TAKA‐1 + BOP was re‐cultured in vitro and designated TAKA‐1 + BOP‐T. Mutation of c‐K‐ ras and p53 oncogenes, chromosomal changes, expression of transforming growth factor alpha (TGF‐α) and epidermal growth factor (EGF) receptor and several biochemical markers were examined in all cell lines. TAKA‐1 + BOP but not TAKA‐1 cells grew in soft agar and produced an invasive tumor in vivo. However, there were no differences in cell growth rate, DNA flow cytometry, or immunohistochemical findings between the non‐transformed and transformed cells. TAKA‐1, TAKA‐1 + BOP and TAKA‐1 + BOP‐T cells all expressed mRNA of TGF‐α and EGF receptor in a comparable pattern. DNA sequence analysis following polymerase chain reaction showed that neither TAKA‐1 nor TAKA‐1 + BOP cells has a mutation of c‐K‐ ras or p53. Karyotype analysis demonstrated that TAKA‐1 + BOP cells had more chromosomal abnormalities compared with TAKA‐1 cells. Mutation of c‐K‐ ras and p53 was not essential for carcinogenesis in hamster pancreatic ductal cells in vitro. In conclusion, immortality of the TAKA‐1 cells caused expression of TGF‐α to the same extent as in malignant cells. Chromosomal and ultrastructural patterns were the only differences detected between the non‐transformed and BOP‐transformed cells. Int. J. Cancer 72:1095–1103, 1997. © 1997 Wiley‐Liss, Inc.