The idea that aberrations in the number or structure of chromosomes can spur tumor formation is more than a century old. Such aberrations--known collectively as "aneuploidy"--arise in two principal ways: as a consequence of abnormal cell division, or as a result of cell fusion. By either mechanism, the resulting aneuploid cells no longer have the proper genetic makeup and frequently die. But researchers now know that tumor cells are often aneuploid--and very much alive. Whether aneuploidy is a cause or a consequence of a cancerous cellular state is the crux of a current debate.
In a recent study, Dr. Yuri Lazebnik and his colleagues at Cold Spring Harbor Laboratory observed, fortuitously, that normal cultured human cells are fused by the action of the Mason-Pfizer Monkey Virus (MPMV), but that the resulting hybrid cells do indeed fail to proliferate. However, the researchers discovered that if one of the fusion partners carried a particular "predisposing" gene mutation (in the oncogenes E1A or Myc, or in the tumor suppressor gene p53), then a significant proportion of the resulting hybrid cells were highly proliferative and thus potentially cancerous.
The missing piece of the puzzle is the question of whether this phenomenon happens in vivo in human bodies.
Whether such proliferating hybrid cells are produced by viruses in the human body, whether they can lead to cancer, and which of the many known and candidate human fusogenic viruses (for example, endogenous retroviruses, whose DNA sequences comprise at least 8 percent of the human genome) might contribute to cancer remain to be determined.
If this result is demonstrated to happen in the body then that will suggest a much larger role for viruses in cancer development.
I'm increasingly convinced we underestimate the size of the benefits that would flow from the development of a wider range of vaccines against viruses and bacteria that rarely kill people. First off, of course getting cold or flu or a stomach virus is unpleasant and also costs time. But also, both the infections and the body's reactions to infections are probably accelerating the aging process. We could reduce the rate of aging by reducing our total lifetime disease load. We might also reduce our risks of cancer.
|Share |||Randall Parker, 2005 November 13 11:11 PM Biotech Cancer|