Telomere maintenance and cancer - look, no telomerase

Activation of a telomere maintenance mechanism seems to be indispensable for the immortalization of human cells. Most cancers and cancer cell lines maintain their telomeres via telomerase. In some cancers, however, telomeres are maintained in the absence of telomerase activity by one or more mechanisms that are known as alternative lengthening of telomeres (ALT). Successful telomere-targeted anticancer therapy might therefore require a combination of telomerase and ALT inhibitors, emphasizing the importance of understanding the molecular details of telomere maintenance mechanisms in immortal cells and their repression in normal cells.