Telomerase and cancer: time to move from a promising target to a clinical reality

The past 25 years have seen unparalleled advances in our understanding of t he molecular basis of cancer. As a result, novel molecular targets have bee n identified that provide great potential for the development of new cancer diagnostics and therapies. Four key features of cancer cells distinguish t hem from their normal counterparts: loss of cell-cycle regulation, loss of control over invasion and metastasis, failure of apoptotic mechanisms, and bypass of senescence. This review examines our understanding of the bypass of senescence and the process of immortalization during carcinogenesis. In addition, the realistic opportunities for telomerase in cancer diagnostics and the challenges faced in clinical trial design for telomerase therapeuti cs are discussed. Copyright (C) 2001 John Wiley & Sons, Ltd.