mrz
12-10-04, 08:54
Switching off gene switches off cancer
12:18 11 October 04
NewScientist.com news service
Cancer cells can revert to harmless cells by switching off a single gene, shows a study of liver cancer in mice.
The gene, which produces a protein called MYC - pronounced “mick” - usually controls cell division. It is implicated in several human cancers, where overexpression of the protein causes rapid cell division, forming tumours.
In the new study, researchers used transgenic mice in which the MYC gene was constantly switched ‘on’ so that too much MYC protein was produced, inducing liver cancer in the mice.
Giving the mice the common antibiotic doxycycline turned the gene ‘off’, and the cells reverted to normal liver cells, but were not destroyed.
“We were definitely surprised that we could make liver cancer cells look like normal liver cells,” says Dean Felsher at Stanford University, California, US, who led the study. “Cells differentiate into more than one cell type and stay that way for months.”
Lying dormant
Withdrawing the antibiotic turned the gene back on so more MYC protein was produced and the cancer, which had been lying dormant, returned. A green dye was used to tag the cells so they could be monitored as they turned from liver cells to cancer cells and back again. The researchers could therefore be certain that the tumours forming were from the same group of cells and not from elsewhere.
“The model is ingenious in that they have constructed an artificial way of turning this gene on or off in the liver of mice,” says Hakon Leffler from Lund University, Sweden. “Humans and normal animals do not have this switch in any of their cells, healthy or cancerous,” he adds, so the technique could not be directly transferred to humans. However, Leffler says the study does suggest a new way of fighting cancer by targeting abnormally high levels of MYC.
“You’d have to target the protein or switch the gene expression off in some way,” agrees John Lunec from Cancer Research UK.
Organ regeneration
The researchers believe stem cell activity is involved. “Liver is really unusual,” says Felsher, as “you can’t usually regenerate an organ but you can with liver tissue”.
If the liver cells retained some stem cell characteristics, he says, it would explain why they were able to revert to normal liver cells with the antibiotic. It would also explain why the tumours were able to reappear once the antibiotic was withdrawn and MYC became overexpressed for the second time.
There is still much to understand. “The next step is to target the MYC protein,” Felsher told New Scientist, “and to validate that it also works on humans.” If it does, it will be a big step forward as the results may apply to several types of cancer.
“The MYC gene is known to be overactive in many types of cancer,” says Elaine Vickers from Cancer Research UK. “Estimates suggest that the gene may contribute to as many as one in seven cancer deaths.”
Journal reference: Nature (DOI: 10.1038/nature03043)
http://www.newscientist.com/news/news.jsp?id=ns99996511
Je kunt natuurlijk ook gewoon meteen zeggen dat je moordenaar cq moordenares bent.... :stomp: :auw: :fuckit2: :motorzaag :terrorist http://www.maroc.nl/nieuws/forums/images/smilies/pissed.gif :kotsen2:
12:18 11 October 04
NewScientist.com news service
Cancer cells can revert to harmless cells by switching off a single gene, shows a study of liver cancer in mice.
The gene, which produces a protein called MYC - pronounced “mick” - usually controls cell division. It is implicated in several human cancers, where overexpression of the protein causes rapid cell division, forming tumours.
In the new study, researchers used transgenic mice in which the MYC gene was constantly switched ‘on’ so that too much MYC protein was produced, inducing liver cancer in the mice.
Giving the mice the common antibiotic doxycycline turned the gene ‘off’, and the cells reverted to normal liver cells, but were not destroyed.
“We were definitely surprised that we could make liver cancer cells look like normal liver cells,” says Dean Felsher at Stanford University, California, US, who led the study. “Cells differentiate into more than one cell type and stay that way for months.”
Lying dormant
Withdrawing the antibiotic turned the gene back on so more MYC protein was produced and the cancer, which had been lying dormant, returned. A green dye was used to tag the cells so they could be monitored as they turned from liver cells to cancer cells and back again. The researchers could therefore be certain that the tumours forming were from the same group of cells and not from elsewhere.
“The model is ingenious in that they have constructed an artificial way of turning this gene on or off in the liver of mice,” says Hakon Leffler from Lund University, Sweden. “Humans and normal animals do not have this switch in any of their cells, healthy or cancerous,” he adds, so the technique could not be directly transferred to humans. However, Leffler says the study does suggest a new way of fighting cancer by targeting abnormally high levels of MYC.
“You’d have to target the protein or switch the gene expression off in some way,” agrees John Lunec from Cancer Research UK.
Organ regeneration
The researchers believe stem cell activity is involved. “Liver is really unusual,” says Felsher, as “you can’t usually regenerate an organ but you can with liver tissue”.
If the liver cells retained some stem cell characteristics, he says, it would explain why they were able to revert to normal liver cells with the antibiotic. It would also explain why the tumours were able to reappear once the antibiotic was withdrawn and MYC became overexpressed for the second time.
There is still much to understand. “The next step is to target the MYC protein,” Felsher told New Scientist, “and to validate that it also works on humans.” If it does, it will be a big step forward as the results may apply to several types of cancer.
“The MYC gene is known to be overactive in many types of cancer,” says Elaine Vickers from Cancer Research UK. “Estimates suggest that the gene may contribute to as many as one in seven cancer deaths.”
Journal reference: Nature (DOI: 10.1038/nature03043)
http://www.newscientist.com/news/news.jsp?id=ns99996511
Je kunt natuurlijk ook gewoon meteen zeggen dat je moordenaar cq moordenares bent.... :stomp: :auw: :fuckit2: :motorzaag :terrorist http://www.maroc.nl/nieuws/forums/images/smilies/pissed.gif :kotsen2: