Suppression of tumorigenicity in human teratocarcinoma cell line PA-1 by introduction of chromosome 4.

Teratocarcinomas are tumors that develop spontaneously in the gonads and usually contain a rapidly dividing, undifferentiated stem cell population. Immature ovarian teratocarcinomas are highly malignant with only 30-60% of patients surviving for 2 years after diagnosis. We have used microcell fusion to introduce individually tagged normal human chromosomes into the PA-1 human teratocarcinoma cell line. Introduction of human chromosome 4 caused a cell morphology in culture and suppressed PA-1 tumorigenicity in nude mice, whereas addition of portions of either chromosome 7 or 12 had no effect on the cell phenotype. The PA-1 cell line regained its tumorigenicity when the tagged chromosome 4 was lost under negative selection. We conclude that there is a putative tumor suppressor gene on human chromosome 4 whose expression interferes with the tumorigenicity of PA-1 cells.