This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables.
WHAT MAKES cancer cells so deadly is their immortality. Normal somatic cells have a mitotic clock that keeps track of the number of times they divide. When that clock runs down, the cell ceases to replicate and becomes senescent. Most cancer cells, however, have found a way to stop their clocks.
According to research findings reported at the American Cancer Society's 37th Science Writers Seminar, in New Orleans, La, the means to stop the mitotic clock appears to be an enzyme that is expressed in early fetal development by germline cells and most cancers, but not by normal somatic cells. The enzyme, called telomerase, enables the cell to maintain the integrity of its chromosomes each time it divides. Without it, the ends of the chromosomes, called telomeres, are whittled away until too much is lost for the cell to maintain normal function. At that point, it ceases to replicate.
Skolnick AA. Cancer Cells' Immortality May Prove Their Undoing. JAMA. 1995;273(16):1247-1248. doi:10.1001/jama.1995.03520400017008