New studies suggest that skin squamous cell carcinoma, like many other human cancers, contain certain cancer cells, known as cancer stem cells, that present increased self-renewal potential that sustain tumor growth. Not much is known about the mechanisms that regulate cancer stem cell functions. Skin squamous cell carcinomas are one of the most frequently occurring cancers in humans.

To dissect the mechanisms that regulate cancer stem cells, the researchers determined which genes are preferentially expressed by cancer stem cell of skin tumors. They found that VEGF, a molecule known to regulate the formation of new vessels, is expressed at high level by skin cancer stem cells, which are located in close contact to the blood vessels. Administration of an antibody that decreases new blood vessel formation to mice presenting skin tumors results in a reduction of the pool of cancer stem cells leading to a reduction of the tumor size, demonstrating that vascular cells regulates skin cancer stem cell functions.

To determine whether VEGF secretion by cancer stem cells directly regulates the function of cancer stem cells, the authors genetically removed VEGF specifically in tumour cells, and found that upon VEGF ablation, skin cancer stem cells are rapidly lost due to a defect in their renewal properties, leading to tumour regression.

“It was extremely exciting to see the complete disappearance of these tumors only two weeks after the treatment” said Benjamin Beck, the first author of the Nature paper.