Faculté de médecine Rockefeller, laboratoire de cytologie analytique (Inserm U. 453) et hôpital Édouard-Herriot, laboratoire d'hématologie, place d'Arsonval, 69003 Lyon, France.
The somatic cells employ a number of pathways to limit their proliferative potential. One of these pathways is cellular senescence. The main cause of senescence of human somatic cells grown in adequate conditions is the shortening of telomeric DNA due to the absence of telomerase activity. Other mechanisms may be triggered independently of telomere length and all have the potential to cause or contribute to cancer. They are called premature senescence and include DNA damage, alterations of chromatin structure and supraphysiological mitogenic signals. A better understanding of these mechanisms will shed new lights on the control of cell proliferation and cancer.