Amplification and activation of c-Ki-ras oncogene in cell line developed from human pancreas explants.

Amplification and activation of c-Ki-ras gene was studied in normal human pancreas and a cell line (T-3) derived from normal pancreas explants exposed to methylnitrosourea (MNU) for 26 weeks. Normal genomic DNAs from pancreas and derived cell lines showed no transforming activity in NIH 3T3 cells. However, DNAs isolated from tumorigenic cell line derived from MNU treated human pancreas explants transformed NIH 3T3 cells.

MNU-induced point mutation and activation of c-Ha-ras oncogene in cell lines derived from human pancreas explants.

Point mutation and activation of c-Ha-ras oncogene was studied at various stages of carcinogenesis in cell lines developed from MNU-treated human pancreas explants. DNAs from normal pancreas and nontumorigenic cell lines showed no transforming activity in NIH 3T3 cells whereas DNA from one of the tumorigenic cell lines transformed NIH 3T3 cells. In this cell line the point mutation was demonstrated to be at codon 12 of c-Ha-ras gene by the loss of an Msp I site.

Loss of a Mr 78,000 marker in chemically induced transplantable carcinomas and primary carcinoma of human pancreas.

Toward the identification of steps in the multiphasic process of human pancreas carcinogenesis we have developed a panel of monoclonal antibodies to normal and carcinogen-treated human pancreas cells. One of these, an IgG3 with strong affinity for a membrane-associated Mr 78,000 protein in fetal and adult parenchymal cells, was purified by high performance liquid chromatography, and used for the detection and characterization of tumorigenic stage in human pancreas carcinogenesis. This protein was present on the cell surface of human pancreas explants exposed to methylnitrosourea for up to 4 months and in nontumorigenic cell lines derived from these explants.

Amplification of c-Ki-ras-2 oncogene sequences in human carcinoma of pancreas.

c-Ki-ras-2 sequences were visualized in paraffin embedded sections from normal adult human pancreases and 24 carcinomas of pancreas by an in situ hybridization technique. A biotinylated 1 kbp EcoRI fragment of pHiHi3 DNA was used as probe and the oncogene was visualized as one or two large grains of reaction products produced in more than 9% of normal pancreas nuclei by streptavidin-peroxidase complex and diaminobenzidine tetrachloride. Its amplification in pancreatic carcinomas was detected as one or more large grains in 54% of the nuclei.

Modulation of a membrane-associated marker in progenitor cells of human pancreas carcinoma.

For the identification of early steps in the multiphasic process of human pancreas carcinogenesis we have developed a panel of monoclonal antibodies to normal and carcinogen-treated human pancreas cells. One of these, an IgG3 with strong affinity for a membrane-associated 46 kd protein (p-46) in progenitor cells of methylnitrosourea (MNU)-treated human pancreas, was purified by h.p.