A protein that normally helps hold healthy skin cells together may also be responsible for the spread of skin cancer, according to researchers at the Stanford University School of Medicine.
In a study published in the journal Science, researchers pointed to a protein called collagen VII for aiding the spread of squamous cell carcinoma, a form of skin cancer that starts growing from the top layer of skin and is linked to sun exposure.
Led by Dr. Paul Khavari, the Stanford team made the association between collagen VII and squamous cell carcinoma following an investigation of a rare skin condition called recessive dystrophic epidermolysis bullosa (RDEB). This condition, which causes blisters on the skin, is caused by a mutation that is linked to altered or missing collagen VII protein.
Dr. Khavari and his team were investigating RDEB in a group of children, two thirds of whom went on to develop squamous cell carcinoma. The finding led them to the theory that the protein was in some way associated with the skin cancer.
Along with colleague Dr. Susana Ortiz-Urda, Dr. Khavari studied skin samples from 12 children who had RDEB and used laboratory tools to activate the molecular mechanisms that normally turn skin cells cancerous.
They were only successful in promoting cancer in eight of the 12 samples, all of which contained the collagen VII protein. In the remaining four samples, the protein was absent and none of the researchers' attempts to turn the cells cancerous worked. But after the introduction of collagen VII, those samples too became cancerous.
Dr. Khavari and Dr. Ortiz-Urda went on to examine the protein's effect in healthy, non-RDEB skin cells, where they used an antibody to block the collagen VII and then tried to induce cancer. "When we blocked this mechanism, we also blocked the cancer from spreading," said Dr. Khavari, noting that while the antibody blocked the cancer, it did not prevent the protein from performing its normal job of keeping the skin intact.
The researchers also tried the protein-blocking antibody on mice that had received transplants of human skin cancer cells. Though the cancer remained, after the introduction of the collagen VII, it failed to spread.
"The cancer isn't deadly unless it spreads," Dr. Khavari said.
Dr. Khavari said the finding could eventually yield a medication that blocks the function of collagen VII associated with the spread of squamous cell carcinoma. Because the Stanford researchers' investigation did not look at other forms of skin cancer, it is unclear whether the antibody could have the same effect on melanoma or basal cell carcinoma.
Squamous cell carcinoma generally first appears as a small lump, which grows from a pre-cancerous condition called actinic keratosis. Actinic keratosis usually occurs on areas of skin that have been exposed to the sun and results in rough, scaly patches that may be red, brown, or the same colour as your skin.
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