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Usually when people think of cancer they think of post-mitotic cells that have accumulated defects in their DNA after successive rounds of division. It is not normally thought about that the defective DNA can be located in the stem cells which actually give rise to tissues during the process of regeneration.
Faulty stem cell link to cancer
08:24am 31st May 2004
Cancers may reappear after apparently being "cured" because of genetically faulty stem cells, scientists have said.
The findings from researchers studying leukaemia cells could lead to radical changes in the way cancer is treated.
They show the DNA glitches which lead to cancer can originate in stem cells - the "blank slate" cells from which different kinds of mature cells develop.
Even if cancer is cleared from a part of the body, it will return if new tissue grows from stem cells that are defective.
Dr John Dick and colleagues, from the University of Toronto in Canada, studied blood cells from human patients with acute myeloid leukaemia (AML) that were injected into laboratory mice.
The researchers identified and tracked individual leukaemic stem cells (LSCs) which reproduced themselves.
The cells were not identical and different LSCs repeatedly generated offspring with different characteristic defects. They then gave rise to characteristic leukaemic cancer cells.
It appeared that AML was not caused by normal stem cells whose lineage later acquired a defect during their development. Instead, it was the "program" in the stem cell itself that was at fault.
The distinction alters the goal of treatment for AML, showing patients must not only be cleared of leukaemic cells, but also the stem cells which produce them.
Reporting the results in the journal Nature Immunology, the scientists pointed out the same principle might apply to other cancers. "The insights into the biology of cancer stem cells gained from leukaemia have been shown to be relevant to other cancers, including solid tumours such as brain and breast cancer."
