Oncogene roles in moles

ﾩ STEPHEN J. KRASEMANN / PHOTO RESEARCHERS, INC

The paper:

The finding:

Two groups of researchers from the Netherlands teamed up with US colleagues to show that the introduction of oncogene BRAFE600 induced cell-cycle arrest in human mole cells in vivo.

The significance:

In vitro work had shown that, under certain conditions, oncogenes signal strong cell-growth arrest. Until this paper, an in vivo correlate had not been demonstrated. Moreover, telomere shortening previously was assumed to be the mechanism. The researchers ruled out telomere degradation-induced senescence by comparing telomere length in mole cells and melanoma metastases using fluorescent in situ hybridization - the naevus showed no significantly shortened telomeres.

The next step:

To further uncover why certain mole cells escape senescence, one of the paper?s senior authors, Daniel Peeper, at the Netherlands Cancer Institute, is now screening for other tumor-suppressing genes that may act as a brake on cell growth when introduced with an oncogene, calling this "the tip of the iceberg." "We speculate that this oncogene-induced [senescence] phenomenon is more widely used by cells to protect from cancer," Peeper says.

Other prospects:

More recent research suggests that oncogene signaling in senescence induces more than tumor-suppressor protein action. Overexpressed oncogenes have been shown to cause DNA-damage, which, among other effects, promotes activation of the tumor suppressor p53.