Involvement of p53 and RB-1 in the immortalisation of human cells

Abstract

Normal diploid mammalian cells undergo a finite number of population doublings in culture before they undergo senescence [Hayflick & Moorhead, 1961]. In contrast, tumours often contain "immortalised" cells that exhibit an apparently unlimited in vitro and in vivo proliferative potential. Fusion of normal and immortalised cells usually results in hybrids with limited proliferative potential [Bunn & Tarrant, 1980; Muggleton-Harris & DeSimone, 1980] indicating that immortalisation is probably due to loss of normal gene function. Similarly, fusion of different immortalised human cell lines with each other often results in mortal hybrids, indicating that the cell lines have become immortalised via different genetic events. Such studies have identified at least four complementation groups for immortalisation, referred to as groups A, B, C and D (Pereira—Smith & Smith, 1988).