Cell Immortalization

The problem of the long-term proliferation of cells is a seminal one. It has always been a hot subject in biology, a source of far-reaching hypotheses, even more so now when explanations for the mechanisms of cell prolifera­ tive mortality or immortality seem within our reach. A question which is still debated is whether an infinite division potential can be a normal trait or is always the result of modifications leading to abnormal cell growth and escape from homeostasis. In general, investigators have been advocates of one of the two extremes, universal limited or unlim­ ited normal proliferative potential. Since the long-term proliferative potential of cells concerns regulation of development, regeneration of tissues, and homeostatic control of cell growth, in brief survival of living organisms, and since the regulation of these processes is so different along the evolutionary scale, it is not surpris­ ing that there does not seem to be any universal trait. The question of whether cells are endowed with finite or infinite prolifera­ tive phenotypes has to be seen using the perspective of comparative biology.

This book describes the most outstanding theoretical hypotheses aiming at explaining the infinite proliferative potential of a cell population, what is now known under the term cell immortalization. It elucidates the phenomenon from an evolutionary point of view, and describes the cell systems used and the experiments performed at the cellular and molecular levels to determine the mechanisms responsible for this cell property. It also appraises how the mortal and immortal phenotypes reflect characteristics of the respective organism, and stresses how this goes beyond the proposal that its opposite, the mortal phenotype, is a mechanism to protect the organism against cancer.