Characterization of new human pancreatic cancer cell lines which propagate in a protein-free chemically defined...

Many human cancer cell lines which have been maintained in fetal bovine serum (FBS)-supplemented medium produce and secrete many substances such as transferrin, alpha 1-antitrypsin, alpha 2-macroglobulin, alkaline phosphatase, gamma-glutamyltranspeptidase, creatine kinase, carcinoembryonic antigen, alpha-fetoprotein, carbohydrate antigen 19/9, and cytokines including colony-stimulating factors and transforming growth factor, and further they may produce small amounts of unknown substances. Usually, small amounts of substances have to be concentrated as highly as possible for detection, but FBS interferes with this procedure. A protein-free culture system is an ideal method for detecting small quantities of substances which originate from cancer cells without interference by FBS. However, we were concerned that protein-free culture may interrupt the production of the substances which have been produced in FBS-supplemented medium. In this study, we investigated the productibility of 46 kinds of well-known substances in ten newly established cell lines derived from human pancreatic cancer. These cell lines were propagated in a protein-free non-FBS-supplemented medium. Of the ten cases, one cell line alone that was derived from acinal cell carcinoma propagated as a semisuspension; on the other hand, nine cell lines that were derived from ductal cell carcinoma propagated as monolayers without piling up. This method prolongs the doubling time, which is not affected by the addition of FBS. The spent media of these cell lines were collected aseptically after the removal of cell debris and concentrated by ultrafiltration using a Pericon cassette followed by lyophilization. Using 46 kinds of available antibodies, we investigated whether or not the substances which react to these antibodies could be detected in the spent media and in the cells by enzyme-linked immunosorbent assay, Western blot analysis, and immunocytochemistry. Among these cell lines, HPC-Y11 produced and secreted the most kinds of substances, and the production of those substances was lowest in HPC-Y0. In conclusion, our protein-free culture system can be available in every laboratory, since this is not only an economical method, but also an effective method for the saving of purification procedures. Moreover, this is a most suitable method for surveying unknown substances derived from cancer cell lines.