(Merkel Skin Cancer - courtesy of DermIS, www.dermis.net)
US researchers have recently discovered a new virus they believe may be linked to a rare but extremely lethal type of skin cancer. Merkel cell carcinoma mostly afflicts the elderly and people with weaker immune systems, including AIDS and transplant patients. The newly discovered virus belongs to the polyoma family, which scientists have studied for more than 50 years because other members of the family have been found to produce cancers in animals. Although polyoma viruses have been suspected of causing human cancers, conclusive proof has been lacking.
Merkel cancer cases have tripled over the past 20 years to about 1,500 a year, and about half the patients with advanced stages of the cancer live only nine months. Two-thirds die within five years.
The University of Pittsburgh Cancer Institute (UPCI) researchers and authors of the paper, Drs Huichen Feng, Masahiro Shuda, and husband and wife, Drs Patrick Moore and Yuan Chang, describe their 10 year programme to perfect the sequencing technology for hunting the virus, which they have named the Merkel cell polyomavirus (MCV). Their work has not established a causal link between MCV and Merkel cell carcinoma (MCC), but if their results can be confirmed, then they are likely to lead to new treatment and prevention approaches.
The scientists identified the virus’s DNA sequence in 80 percent of Merkel cell tumors. The virus penetrates tumor cells in a pattern indicating that the infection precedes (comes before) the cells’ growth into a cancer, they said. The researchers believe the new virus produces a carcinogenic protein and blocks a gene that stops the growth of cancer cells.
The polyoma virus is the seventh virus linked to human cancers, Dr. Moore and Dr. Fauci said. The others, in addition to the Kaposi’s sarcoma virus, are hepatitis B and C viruses, linked to liver cancer; papilloma virus, to cervical cancer; Epstein-Barr virus, to cancer of the nose and pharynx and to Burkitt’s lymphoma; and HTLV-1, or human T-cell leukemia virus 1.
The findings raise new scientific challenges. One is to determine any links between the virus and other diseases. Among this team’s next steps is an effort to determine whether a virus is related to Hodgkin’s and non-Hodgkin’s lymphoma, Dr. Moore said.
Dr. Moore and Dr. Chang discovered human herpes virus 8, which causes Kaposi’s sarcoma, the most common malignancy in AIDS patients.
Elaine Warburton
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