UCLA researchers reported Thursday that they have discovered the identity of the prostate cell that goes awry to produce cancer, a finding that could lead to new approaches to prevention and treatment of this common plague of men. Most researchers had previously believed that prostate tumors originated in the so-called luminal cells because tumor cells look like luminal cells. But immunologist Owen N. Witte of UCLA's Jonsson Comprehensive Cancer Center and his colleagues have found that it actually arises in basal cells, a more stem cell-like component of the gland.
The prostate is filled with a network of small tubules. The insides of these tubules are lined with luminal cells, which produce fluids and proteins that aid reproduction. Basal cells form the outside core of the tubules.
Owen and his team had originally developed a series of surface markers that allowed them to readily distinguish basal cells from luminal cells. They then showed that, in mice, it is the basal cells that produce tumors.
They reported in the journal Science their new findings that the same is true for humans. The team isolated basal and luminal cells from healthy human prostate tissue, then treated them with a genetically engineered virus containing three genes known to trigger cancer. Finally, the cells were implanted in mice with no immune systems. The basal cells went through three distinct stages, first growing into prostate-like tubules, then transforming into damaged pre-cancerous cells and finally turning malignant. The luminal cells did not change. Tellingly, when the tumors were examined by a pathologist, they appeared identical to those found in men, said Andrew Goldstein, a Ph.D. student in Witte's lab who is the lead author of the paper.
The findings add to the growing body of evidence that tissue-specific stem cells found in various organs often grow out of control to form cancers, Witte said. And now that scientists know which cells cause prostate tumors and the pathway they take to get there, it may be possible to devise new drugs to treat them and even medications to prevent transformation at an early stage.
-- Thomas H. Maugh II