Tumor suppressor gene linked to stem cells, cancer biologists report

The p53 gene appears to be involved in signaling other cells instrumental in stopping tumor development. But the p53 gene predates cancer, so scientists are uncertain what its original function is.

In trying to unravel the mystery, Dr. John Abrams, Professor of Cell Biology at UT Southwestern, and his team made a crucial new discovery -- tying the p53 gene to stem cells. Specifically, his lab found that when cellular damage is present, the gene is hyperactive in stem cells, but not in other cells. The findings suggest p53's tumor suppression ability may have evolved from its more ancient ability to regulate stem cell growth.

"The discovery was that only the stem cells light up. None of the others do. The exciting implication is that we are able to understand the function of p53 in stem cells," said Dr. Abrams, Chair of the Genetics and Development program in UT Southwestern's Graduate School of Biomedical Sciences. "We may, in fact, have some important answers for how p53 suppresses tumors."

The findings appear online in the journal eLife, a joint initiative of the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust.

p53 is one of the hardest working and most effective allies in the fight against cancer, said Dr. Abrams. It regulates other genes, marshaling them to carry out an untold number of preemptive attacks and obliterate many pre-cancerous cells before they ever pose a threat. In nearly every case where there's a tumor, p53 is damaged or deranged, strongly suggesting that it is a tumor suppressant.

Stem cells are one of the body's most useful cells because of their regenerative capabilities. Stem cells produce daughter cells, one that is a stem cell and another that can become virtually any kind of cell that's needed, such as a blood cell or a kidney cell. Stem cells have received tremendous attention in cancer research because of the stem cell hypothesis. That hypothesis maintains that malignant tumors are initiated and maintained by a population of tumor cells that have properties similar to adult stem cells.

"What this new finding tells us is that an ancient functionality of p53 was hard-wired into stem cell function," said Dr. Abrams, senior author. "From the standpoint of trying to decipher cancer biology, that's a pretty profound observation."