Telomerase as a target for cancer therapy.

Normal human somatic cells undergo telomeric attrition and replicative senescence because of inadequate levels of telomerase; however, most immortal cancer cells cope with this by deregulating telomerase. Inhibiting telomerase causes renewed telomeric attrition and eventually highly specific death in cancer cells that express the enzyme. However, most cancer cells undergo many cell divisions before they die, opening the way for acquired drug resistance.