Cell pathway on overdrive prevents cancer response to dietary r...( FINDINGS: Whitehead Institute resear...),Health

FINDINGS: Whitehead Institute researchers have pinpointed a cellular pathway that determines whether cancerous tumors are susceptible to dietary restriction during their development. When this pathway, known as PI3K is permanently turned "on" via mutation, tumors grow and proliferate independent of the amount of food consumed. However, when the PI3K pathway operates normally, tumors respond to dietary restrictiondefined as food consumption limited to 60% of normal--and become smaller in size.

RELEVANCE: Scientists have known about the correlation between dietary restriction and tumor growth since the early 20th Century. These findings bring clarity to the long-unanswered question of why certain tumors are unaffected by reduced caloric intake.

CAMBRIDGE, Mass. (March 11, 2009) Whitehead Institute researchers have pinpointed a cellular pathway that determines whether cancerous tumors respond to dietary restriction during their development.

Studying human cancer cell lines in mice, researchers have found that when this pathway, known as PI3K, is activated permanently via mutation, tumors grow and proliferate independent of food consumption. However, when the PI3K pathway operates normally, dietary restriction (defined as a 60% reduction in normal intake), results in smaller tumors. The findings are published online in the March 11 issue of Nature.

"Our findings indicate that each tumor cell bears a signature that determines whether or not that cell will be affected by dietary restriction," says Nada Kalaany, first author of the paper and a postdoctoral researcher in the lab of Whitehead Member David Sabatini. "We think that mutations in the PI3K pathway are a major determinant of the sensitivity of tumors to dietary restriction."

The connection between food consumption and tumor growth is not new. In the early 20th Century, scientists first noted the correlation between a restricted diet and decreased tumo
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