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April 1st, 2008
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Mice given a high dose of chemotherapy after fasting continued to thrive. The same dose killed half the normally fed mice, and caused lasting weight and energy loss in the survivors. The chemotherapy worked as intended on cancer, extending the lifespan of mice injected with aggressive human tumors, reported a group led by Valter Longo of the University of Southern California. Test tube experiments with human cells confirmed the differential resistance of normal and cancer cells to chemotherapy after a short period of starvation.
The idea for the study came from the Longo group’s previous research on aging in cellular systems. About five years ago, Longo was thinking about the genetic pathways involved both in the starvation response and in mammalian tumors. When the pathways are silenced, starved cells go into what Longo calls a maintenance mode characterized by extreme resistance to stresses. In essence the cells are waiting out the lean period, much like hibernating animals. But tumors by definition disobey orders to stop growing because the same genetic pathways are stuck in an "on" mode. That could mean, Longo realized, that the starvation response might differentiate normal and cancer cells by their stress resistance, and that healthy cells might withstand much more chemotherapy than cancer cells.
I wish we'd known this when my grandfather was dying of cancer two years ago.