A particular biochemical causes new blood vessels to sprout, feeding melanoma tumor growth, and has been found to be the best measurement yet of how far along a skin cancer has progressed, according to a recent study.

The study, performed by Hellmut Augustin and Dirk Schadendorf of the German Cancer Research Center and Mannheim Medical Faculty of the University of Heidelberg, examined the role of a growth factor called angiopoietin-2 (Ang2) in malignant melanoma.

Ang2 promotes the sprouting of blood vessels, a process known as angiogenesis, to bring oxygen and nutrients to the fast-growing cells of a tumor. It does so by linking with a receptor known as Tie2 in the endothelial cells on the interior of blood vessels, inducing the formation of new capillaries.

The two researchers and their colleagues measured Ang2 levels in blood samples of melanoma patients and found a strong correlation between ever-higher Ang2 concentrations and increasing tumor size and more advanced disease stages. The Ang2 blood level, in fact, was found to be a better measure of disease progression than any to date. Confirming their discovery, they noticed that people whose cancer is stable or slow-growing have lower Ang2 levels.

The research team also decided to check whether eliminating melanoma cells' Ang2 production would affect a tumor's malignant properties. The scientists used a genetic engineering method to switch off the manufacture of Ang2 in these skin cancer cells in a laboratory dish. Tests then showed that the cells were no longer able to migrate, or metastasize, to other tissues of the body, which is how a highly malignant cancer can kill a person.

"Ang2 is a very promising candidate, both as a biomarker for better monitoring of disease progression and as a target structure for therapy measures," Augustin said of the results. Blocking Ang2, he speculated, might not only choke off the tumor's blood supply, but also throttle down its malignant growth and potential for migration.

Source: http://www.eurekalert.org/pub_releases/2009-03/haog-anm031209.php

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