MOLECULAR LINKS BETWEEN CELLULAR MORTALITY AND IMMORTALITY (REVIEW)

Normal diploid cells cultivated in vitro exhibit limited division pote ntial while undergoing ageing during serial passaging. In contrast, ce lls that have been genetically transformed appear to have lost the reg ulatory mechanisms of limited growth potential and may continue to div ide indefinitely. While cellular mortality is characterised by a progr essive cessation of cell growth manifested in cell culture by senescen ce, immortalisation is the escape from senescence as a result of multi ple mechanisms involving the inactivation of tumour suppressor genes, the elevated expression of oncogenes, as well as other genetic and epi genetic changes. The mechanisms governing mortality and immortality ar e fundamentally linked. The physiological and biochemical features whi ch characterise cellular mortality are examined, herein in the search for markers and timing mechanisms of mortality. The genetic elements i nvolved in the control of mortality and immortality are also discussed , and the fundamental similarities between the molecular and genetic a spects which govern the determination of the phenotypes manifesting th e two precesses are underlined.