The c-Harvey-ras-1 oncogene in chromosome mediated gene transfer

Transfection of DNA derived from a variety of tumours can induce morphological transformation of certain immortalised but normally contact-inhibited cell lines. This important technique has been instrumental in the identification and subsequent molecular cloning of a number of oncogenes, including Harvey-ras. We can extend this approach for studying neoplastic potential by performing chromosome-mediated, as distinct from DNA-mediated, gene transfer. This modification offers two potentially important advantages, both of which stem from the fact that sub-chromosomal lengths of DNA are transferred. Firstly, the expression of the oncogene can be studied in its normal chromosomal milieu; potential modifying effects of linked and unlinked sequences can be evaluated. Secondly, new chromatin segments with transforming potential but too large to be transferred as naked DNA may be revealed. Our experiments illustrate some of the new insights into the molecular basis of neoplastic change which can be gained by this technique. They also demonstrate the power of the technique as a genetic tool for the isolation and detailed molecular analysis of oncogene-associated, sub-chromosomal regions of the human genome.