Dysfunction of the tumor suppressor gene PTEN may be responsible for 30 to 60 percent of melanomas, according to an article in the June 1st issue of Cancer Research. The insight into the genetics underlying tumor formation of a substantial proportion of melanomas may lead to therapies that enhance the normal apoptosis-triggering activity of the gene.

"Although the incidence of melanoma has been on the rise for years, few advances have been made in its treatment," said Gavin Robertson, Ph.D., a coauthor of the study. "These discoveries may lead to another crucial weapon in the rather small arsenal of treatments available for this dangerous disease and offer the first hope for a new melanoma treatment target in decades."

In the current work, investigators used chromosome transfer technology to insert an entire chromosome 10 (containing a functional PTEN allele) into melanoma cells. The introduction of chromosome 10 temporarily switched off tumor cell growth in vitro and in mice with transplanted tumor cells. Apoptosis resumed, and the malignant cells were destroyed.

"When these normal genes are introduced into melanoma cells, they can no longer multiply," Robertson said. "It's essentially a red light telling the cells you can't form tumors."

Although chromosome transfer temporarily slowed tumor growth, the melanoma cells eventually started to divide again, illustrating additional genetic change. The findings suggest that introducing functional PTEN into melanoma cells using a harmless virus could be a useful therapeutic approach for killing melanoma cells. "As we add to the treatment possibilities, we give patients more chances to beat the cancer," Robertson said.

He noted, however, that the most critical message remains prevention. "Detected early, melanoma has a 100 percent cure rate," Robertson said. "If you've ever had sunburns, make sure you monitor moles and see a dermatologist once a year, and be sure to put sunblock on your children. Most, about 80 percent, of the sun damage accrued during a person's life occurs in the first 18 years of life."