Human tumor cell identification in short-term cultures by combined microdensitometry and autoradiography

Several groups are using short-term cultures of human tumor specimens as models to study cancer. When cells from a biopsy are grown in this way, it is essential to confirm that the tumor cells and not the normal stromal cells have been cultured. This paper reports the use of combined microdensitometry and autoradiography to identify tumor cells in cultures prepared from different types of malignancy, especially abdominal tumors, melanomas and gliomas. Cells of known origin were analyzed to provide standards. Three main results were shown. (1) Provided that the tumor cells have DNA values which differ from normal by at least 10%, they can be identified when the cells are first put into culture, and their presence can be confirmed at later stages. (2) The proportion of normal and tumor cells can be estimated, and the presence of just 10% normal cells can be detected, so new culture methods designed to favor the growth of tumor cells can be evaluated. (3) Most types of tumor are suitable for analysis, but when biopsies contain a high proportion of stromal fibroblasts, there is a real danger that after about 20 days in culture the normal cells will overgrow the tumor cells. An attempt to distinguish tumor cells which have normal DNA values from normal cells on the basis of a different optimum hydrolysis time with hydrochloric acid was unsuccessful.