Some brain tumors may be mediated by tiny filamen...( UCSF scientists have discovered that...)

UCSF scientists have discovered that a tiny filament extending from cells, until recently regarded as a remnant of evolution, may play a role in the most common malignant brain tumor in children.

The study, conducted in mice and in human brain tissue of medulloblastomas, coincides with a study by another team of UCSF scientists showing that the structure, known as primary cilium, also may play a role in basal cell carcinoma, the most common form of skin cancer. (See related UCSF news release.)

The findings, both reported online on August 23, 2009 in "Nature Medicine," are the first direct evidence of a role of primary cilia in cancer, which the researchers say could lead to a new strategy for diagnosing subtypes of cancers and to potential targets for therapy.

"These findings are very exciting," says the senior of the medulloblastoma study, Arturo Alvarez-Buylla, PhD, UCSF Heather and Melanie Muss Professor of Neurological Surgery and a member of the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UCSF.

"In the last few years, primary cilia have been shown to be essential for the cell-signaling that drives both human development, including the differentiation of stem cells into neurons, and some diseases, including polycystic kidney disease. The fact that the two UCSF studies implicate primary cilia in two totally different tissues suggests the finding is likely to be very general."

Significantly, in both UCSF studies, the findings in mice revealed that primary cilia had opposing roles in cancers depending on which mutated genes initiated the aberrant cell-signaling events to begin with. When one particular mutated protein was activated, removal of the cilium prevented the onset of disease; when another particular gene was activated, absence of the cilium allowed cancers to develop.

Remarkably, an analysis of human tissue in the medulloblastoma study revealed that primary cilia were present
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