Role of Telomeres and Telomerase in Cancer

Cancer cells are distinguished from normal cells by two major characteristics: lack of regulation and limitation in their proliferation. The former is essential and represented as “transformed” with anchorage independency and invasive capabilities, while the latter is not a prerequisite but highly associated and represented as “immortal” concomitant with activation of telomerase. Telomerase is activated in around 80% of human cancers but not in usual somatic cells, and it is responsible for the indefinite proliferation capacity of cancer cells. Therefore, it is natural for physicians to expect telomerase to be useful as a diagnostic and therapeutic target in human cancers. In this chapter, we will overview the characteristics of telomeres and telomerase in human cancers.