Transforming activity of DNA extracted from human urological tumours

The transforming activity of DNA extracted from one testicular cancer, one benign prostatic hyperplasia, two malignant prostatic adenocarcinomas, six renal cell carcinomas, two tumours of the renal pelvis, a specimen of normal urothelial tissue, two benign papillomas of the bladder and five malignant bladder carcinomas, was investigated using a DNA transfection assay on primary cultures of hamster kidney cells (HK cells) and mouse embryo fibroblasts (MEF cells). Transformation was scored under light microscope by the appearance of foci of morphologically transformed cells and by evaluating the ability of the transfected cells to from colonies in soft agar. Primary HK cells were unable to support transformation by human tumour DNA because of their very limited lifespan in vitro; MEF cultures, on the contrary, had a much more prolonged life: but were only abortively transformed by DNA from four out of six renal cell carcinomas and four out of seven malignant urothelial tumours, suggesting that transforming genes are present but not activated in the DNA from these urological malignancies.