Viruses in human cancers
Article Abstract:
Some viruses may contribute to the development of cancer only indirectly. An example is human immunodeficiency virus (HIV), which is not known to cause cancer directly, the immunosuppression that results from HIV infection permits cancers such as Kaposi's sarcoma and B-cell lymphomas to develop without impediment. Other viruses have been implicated in the development of human cancers, but direct evidence remains elusive. An example is the herpes simplex viruses, which have been statistically correlated with oral cancers and anogenital cancers. However, other viruses are clearly involved in the development of some human cancers, including Epstein-Barr virus (EBV), which is linked to Burkitt's lymphoma in African children and to nasopharyngeal carcinoma. EBV is also implicated in B-cell lymphomas in patients immunosuppressed by either HIV or by post-transplant drug treatment. Some researchers suspect that EBV may play a role in Hodgkin's disease. Another virus that causes cancer is the human T-cell leukemia-lymphoma virus type I (HTLV-I). Similarly, the several types of human papillomavirus (HPV) are strongly implicated in the development of anogenital cancer. There are over 60 types of HPV, which cause warts. Some types, such as 16 and 18, are thought to cause several types of cancer, including cancer of the cervix. Other types, such as 6 and 11, are often found in warts, but are rarely involved in the development of malignancies. Hepatitis B virus is thought to cause hepatocellular carcinoma, a form of liver cancer, particularly in China and Africa where this cancer is endemic. About 15 percent of all cases of cancer can be directly related to a human virus, making viruses second only to tobacco as a risk factor for cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1991
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An RNA-based information superhighway in plants
Article Abstract:
Cosuppression is a mechanism that suppresses the expression of a plant's own genes when high-expressing transgenes are introduced. Research indicates that an RNA-based system transmits the cosuppression state between plant cells.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1998
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