Telomeres and cancer: barriers break down

The extremities of chromosomes, Or telomeres, play a critical role in the c ontrol cell proliferation. Changes in their structure can induce either an arrest of cell division (replicative senescence) or cell death (apoptosis). Those "telomeric barriers against proliferation" can stop the development of tumor cells. Some recent results obtained with mice lacking a functional telomerase enzyme and in successive generations of mice doubly inactivated for telomerase and the INK4a or the p53 tumor suppressor genes are particu larly relevant to oncogenesis. It appears that manipulating telomeres becom es a challenge for the design of future anti-oncogenic approaches.