Study Reveals Trigger That May Speed Melanoma
WEDNESDAY, March 28 (HealthDay News) -- Growth of the deadly
skin cancer melanoma may be triggered by the immune system turning
on itself, according to a new study that also identified the
mechanism that causes this to happen.
Melanoma accounts for only about 5 percent of skin cancers, but
is the cause of most skin cancer deaths, American Cancer Society
statistics indicate. The disease is often curable in its early
stages but is difficult to treat once it has spread invasively, the
authors of the new study noted.
The study, published in the current edition of the journal
Science Translational Medicine, focused on a specific immune-inhibiting molecule called B7-H1 in melanoma tumors.
In patients with tumors that expressed B7-H1, suppression of the
inflammatory immune response sped the growth and increased the
aggressiveness of their tumors, the researchers from Yale School of
Medicine and Johns Hopkins Medical Institutions found.
The investigators also found that tumor cells somehow use a
component of the immune system itself (interferon gamma) to turn on
B7-H1 and suppress the immune system.
"We were surprised to find that aggressive tumors can not only escape or hide from infiltrating immune cells, but can go on the attack -- using interferon gamma as a weapon against the immune system," lead author Dr. Lieping Chen, a professor of immunobiology at Yale School of Medicine and director of the cancer immunology program at Yale Cancer Center, said in a Yale news release.
This mechanism may be responsible for immune suppression and
tumor growth in up to 40 percent of melanoma patients, Chen said.
The finding may make it possible to develop therapies that block
this immune-suppressing ability, he added.
The American Cancer Society has more about
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