Study finds a Protein that Helps Suppress Cancer Fades as we Age

Images showing the difference in the prevalence of p53 in the oral tissue of a 28-year-old (left) and a 74-year-old (right). Credit: Dr. Reuben Kim

UCLA researchers 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, UCLA School of Dentistry dean and his team have been studying p53, tumor suppressor protein, “guardian of the genome” involved 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 Park. Previous studies have shown 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 epithelial cells lining the skin and the mouth, the level of p53 is reduced, rather than enhanced when cells age. These cells have a set level of p53 that provides protection from environmental factors and ensures their wellbeing. With less p53, older epithelial cells have a harder time maintaining the integrity of their genetic material when they encounter carcinogens, which allows cancer to develop. The level of p53 in skin and mouth epithelial cells decreased with age by epigenetic factors, not by the changes of the p53 DNA sequence.

“Inasmuch as approximately 90% of human cancers are originated from epithelial cells, we suspect this may have to do with the increased incidences of skin and oral cancers in elderly patients,” said Dr. Reuben Kim. http://medicalxpress.com/news/2015-07-protein-suppress-cancer-age.html