“Guardian of the Genome” Protein (p53) Levels Decline with Age in Certain Epithelial Cells As Result of Epigenetic Changes; Increased Cancer Risk May Result

Researchers at UCLA have found that a protein that serves as a suppressor of cancer diminishes in skin and mouth epithelial cells as the human body ages. Dr. No-Hee Park, Dean of the UCLA School of Dentistry, and his research team have been studying p53, a tumor suppressor protein known as “the guardian of the genome” because of its involvement in DNA repair, cell cycle regulation, and cellular deterioration. “Looking at ways to maintain levels of p53 as one ages may provide a therapeutic clue to preventing cancer development,” said Dr. Park, who is also a Distinguished Professor in the Departments of Dentistry and Medicine at UCLA. Previous studies have shown that p53 accumulates in large quantities as connective tissue cells, called fibroblasts, age and stop dividing. It has been believed that the accumulation of p53 causes cells to stop dividing, which prevents out-of-control cells from growing into tumors. In an open-access article published online on July 1, 2015 in Aging Cell, the UCLA researchers found that in epithelial cells lining the skin and the mouth, the levels of p53 are actually reduced, rather than increased when cells age. Epithelial cells line the major cavities of the body, including most organs, such as the mouth, stomach, small intestine, kidney, and pancreas. These cells have a set level of p53 that provides protection from environmental factors and ensures the wellbeing of these cells. With less p53, older epithelial cells have a harder time maintaining the integrity of their genetic material when they encounter carcinogens, and this difficulty can allow cancer to develop. Dr.
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