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Cancer Cells Don’t Age!
Copyright 1988 Massachusetts Medical Society. All rights reserved.
Electronically reproduced at DR B’S BBS by permission from the publisher.
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7. UNRAVELING THE BIOLOGY OF CELLULAR AGING
We grow old because our cells grow old — a process we think of as inevitable and immutable.
Cancer cells, however, seem to escape the process of aging and become “immortal.” This review of recent research sheds some light on the cellular aging process and suggests a connection between the biology of cellular aging and the biology of cancer.
Investigators have observed that a human diploid fibroblast placed in a cell culture goes through a limited, predictable number of replications before it stops dividing.
Moreover, the replicative life span of an animal’s fibroblasts has been shown to correlate with the life span of the species. When a fibroblast becomes senescent, its growth is stopped at a particular part of the cell cycle (the G1/S boundary) and it ceases to respond to certain growth factors.
Certain growth-inducing proto-oncogenes seem to be turned off, while concentrations of possibly growth-retarding proteins seem to be increased.
Researchers speculate that cancer cells circumvent the mechanisms of senescence, and experiments have shown that specific molecular manipulations can cause a senescent cell to begin dividing again.
It remains to be shown whether further understanding of cellular aging will have implications for the control of aging in plants and animals, but the prospect is exciting. — ALK.
Replicative senescence: the human fibroblast comes of age.
Science 1990 Sep 7; 249:1129-33