The easy-to-detect tumor suppressor promyelocytic leukemia protein (PML) may help distinguish benign tumors from cancers, now that researchers have discovered that benign tumor cells produce the PML molecule and display abundant PML bodies.

A research team led by Gerardo Ferbeyre, MD, PhD, of the University of Montreal’s department of biochemistry, also found that malignant cancer cells either don’t make PML bodies or fail to organize them, allowing the cancerous cells to proliferate uncontrollably.

In earlier research, Dr. Ferbeyre discovered that PML is able to force cells to enter senescence—the mature stage in a cell’s life at which it can no longer reproduce. Senescence is a natural defense against cancer formation.

The latest work demonstrated the mechanism by which senescence was achieved. Patient samples revealed that in benign prostatic hyperplasia—a neoplastic disease that displays features of senescence—PML was up-regulated and formed nuclear bodies. “In contrast,” wrote the authors in their online report for Genes & Development, “PML bodies were rarely visualized in prostate cancers.”

The investigators noted that this new information may be used to help distinguish benign tumors from cancer, and may aid the design of targeted therapies that can induce senescence in tumors.