Class 7 (Disconcogenes)

Class 7 (Disconcogenes) - The Discovery of Oncogenes...

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The Discovery of Oncogenes Reading: Ergito.com, Under “Great Experiments” Steven Martin : Identification of a retroviral transforming gene Robert Weinberg : The discovery of oncogenes in human tumors
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Historical context: Infectious diseases, 1880-1890’s (Pasteur, Koch): Terrible diseases with microbial or viral etiology: Tuberculosis, cholera, rabies, diphtheria…. Was cancer just another infectious disease that would succumb to the powers of the microbiologists?
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The “cancer microbe” idea was discredited by many, including noted American pathologist, James Ewing (of Ewing’s Sarcoma fame). "Few competent observers consider [the parasitic theory] as a possible explanation in cancer. The general facts of the genesis of tumors are strongly against the possibility of a parasitic origin.” (1919)
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Canine Transmissible Venereal Tumor (CTVT) Long suspected that a sexually transmitted virus caused CTVT, however there was no direct evidence for this. The graft hypothesis: tumor cells,themselves, are transmitted from dog to dog. Examination of tumors from dogs on five continents showed that tumors cells are more closely related to each other than even the most in-bred breed of dog. Original tumor thought to have arisen 250-2,500 years ago in a single dog in Asia (maybe a Shih Tzu) QuickTime ö and a TIFF (Uncompressed) de are needed to see this p Anything like this in humans? Cases of organ transplant, bone marrow transplant patients developing tumors from donor tissue What about contagious forms of cancer?
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State of Cancer Research, 1920: Chemicals and radiation could provoke cancer: Pott (1775) Yamagiwa (1915) Physicists, X-rays, and leukemia
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1908, Ellerman and Bang: isolation of a virus that caused leukemia in chickens Important w.r.t. to cancer only in retrospect, since leukemia wasn’t recognized as being a type of cancer 1909: Peyton Rous (Rockefeller University) Chicken farmer from Long Island brought him a Plymouth Rock hen with a large sarcoma of the breast muscle
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Rous killed the chicken, ground up the tumor, injected extract into breast muscle of another chicken. · Sarcoma developed at site of injection · Due to injection of tumor cells, or infectious agent? · Filtered extract, injected another chicken, tumor developed again. RSV - Rous Sarcoma Virus - a single isolate from a single chicken would prove instrumental in the discovery of oncogenes 50 years later.
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Rats identified with stomach cancers in Copenhagen sugar refineries. Concluded that this was caused by a parasitic nematode in cockroaches, eaten by the rats. Not…. in fact the rats didn’t even have stomach cancer, but a type of metaplasia of unknown cause, and this was later shown to occur in controls rats at similar rates. Fibiger became ill the day of the Nobel presentation and died six weeks later from bona fide cancer (colon carcinoma).
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Class 7 (Disconcogenes) - The Discovery of Oncogenes...

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