At least according to the article below. Seems to completely change the approach to dealing with cancer since the cancer stem cells don't have a life cycle like cancerous non-stem cells. Roger ------ http://virtualtrials.com/news3.cfm?item=2410 March 11, 2004 Stem Cells in Tumors May Help Explain Some Cancer Mysteries If anyone still has doubts that the 1950s are a bygone era, consider some experiments scientists conducted then without raising eyebrows (let alone lawsuits). To probe the basics of cancer, a team of scientists injected cells from patients' colon, lung, ovarian and other tumors into the patients' own thighs. After trying this with varying numbers of cells, the scientists found that the transplants regenerated a tumor in the thigh (or in a mouse) only if at least one million cells were injected. If the bioethics of the 1950s fell short of today's, the science was a harbinger of an upheaval now shaking cancer biology. After going nowhere for decades, those old results have finally led to a revolutionary insight. "Within a tumor mass, there is only a small population of cells that can spawn more tumor; other cells in the tumor can't," says cancer biologist Robert Weinberg of the Whitehead Institute, Cambridge, Mass., who discovered the first human oncogene. The existence of these "tumor stem cells" promises to explain one of the more perplexing, and tragic, mysteries of cancer treatment. Biologists have made great strides in identifying molecular pathways by which cancer cells grow and spread. But although Iressa shrinks non-small-cell lung cancers, Erbitux shrinks advanced colorectal cancers and the just-approved Avastin shrinks metastatic colorectal cancer -- in each case, in only some patients -- the drugs prolong survival by mere months or not at all. The reason, says Dr. Weinberg, may be that "killing off the majority of cells in a tumor will still leave it with the ability to regenerate another tumor, from these stem cells." Eradicating the non-stem cells in a tumor "may result in a remission" and even the appearance of being cancer-free, explains molecular biologist John Dick of the University of Toronto, but "the disease will relapse if the tumor- initiating cells are not eliminated." Discovering that only some cancer cells are able to generate more tumor has been a struggle, as the lag between those 1950s experiments and today shows. "The idea of cancer stem cells has been around for a long time," says biologist Irving Weissman of Stanford University. But no stem cell (normal or cancerous) had been isolated until he and his colleagues identified blood- forming stem cells in mice in 1987, and in humans in 1992. Seizing on this method for differentiating stem cells from others, Dr. Dick and his team discovered in 1994 that, in leukemia, only some cells have the ability to spawn more tumor. The Toronto team dubbed them "leukemic stem cells." It was an uphill struggle to figure out whether blood cancers are unique, or whether solid tumors have cancer stem cells, too. But after begging the university for a crucial $500,000 machine, biologists led by Michael Clarke and Muhammad Al-Hajj of the University of Michigan, Ann Arbor, found last year that breast cancer consists of a few cancer- initiating cells that can make more breast-cancer cells, seemingly forever, surrounded by an ocean of noncancer- initiating cells. Although the two kinds of cells looked identical, on closer inspection there were several "markers" -- think of them as microscopic flags poking up from the cell's surface -- that distinguish a breast-cancer stem cell from the cells in a breast tumor that can't generate more tumor. When the Michigan team injected as few as 100 cells of the former into mice, breast tumors grew every time. Not even tens of thousands of noncancer stem cells produced a tumor. Since the Michigan discovery, researchers in Japan and Canada have found brain-cancer stem cells; stem cells likely exist in other solid tumors, too. Dr. Clarke estimates that breast cancer stem cells make up as little as 3% to 5% of some tumors. That's the good news. Those are the only cells you have to kill to cure cancer, because non-stem cells eventually die off on their own. Even when non-stem cells spread, they don't pose much danger because they die after dividing a few times. The goal of current chemotherapy, to kill as many cells as possible, can probably be dialed back. The bad news is that standard chemo hits tumor cells at a vulnerable point in their life cycle, but cancer stem cells don't seem to cycle this way. "I think the reason cancer therapy does not cure all cancers has to do with the unique properties" of the cancer stem cell, says Dr. Dick. Ever more sobering, the molecular pathways that scientists have recently identified, with much fanfare, as allowing cancer cells to grow may not be critical after all. If such a pathway promotes growth in the zillions of cells that are not cancer stem cells, it may be inconsequential. The only pathways that matter are those that keep the miscreants alive and thriving. Or as Dr. Weinberg told me, "tumor stem cells may explain why you can have tumor shrinkage but not life extension. If current chemotherapies don't target tumor stem cells, the cells keep making more tumor." On the bright side, knowing which cells they have to kill gives scientists a better shot at finding therapies that do that. "I'm optimistic we can figure this out," says Dr. Clarke.
"Roger" <[email protected]> wrote in message news:[email protected]... > At least according to the article below. Seems to > completely change the approach to dealing with cancer > since the cancer stem cells don't have a life cycle like > cancerous non-stem cells. > > Roger > It's been well established for 30 years that only a small proportion of the cells in a cancer are able to continually divide and spread. In many sarcomas, the Cell Loss Factor is as high as 99% So this is nothing new, and nothing useful
"Steph" <[email protected]> wrote in message news:[email protected]... > > "Roger" <[email protected]> wrote in message news:O3d4c.345- > [email protected] > > At least according to the article below. Seems to > > completely change the approach to dealing with cancer > > since the cancer stem cells don't have a life cycle like > > cancerous non-stem cells. > > > > Roger > > > > It's been well established for 30 years that only a small > proportion of the > cells in a cancer are able to continually divide and > spread. In many sarcomas, the Cell Loss Factor is as high > as 99% So this is nothing new, and nothing useful The findings about the existence of the cancer stem cells appear to be new. The fact that they have a different life cycle than "harmless" cancer cells appears to be new. As for the findings being not useful, well maybe not yet. But I think this is a necessary step to move to the next step (targeting treatments at the cancer stem cells) so in the end I think it will be not only useful but a necessary finding. Roger
"Roger" <[email protected]> wrote in message news:[email protected]... > > "Steph" <[email protected]> wrote in message > news:[email protected]... > > > > "Roger" <[email protected]> wrote in message news:O3d4c.3- > > [email protected] > > > At least according to the article below. Seems to > > > completely change the > > > approach to dealing with cancer since the cancer stem > > > cells don't have a > > > life cycle like cancerous non-stem cells. > > > > > > Roger > > > > > > > It's been well established for 30 years that only a > > small proportion of > the > > cells in a cancer are able to continually divide and > > spread. In many sarcomas, the Cell Loss Factor is as > > high as 99% So this is nothing new, and nothing useful > > The findings about the existence of the cancer stem cells > appear to be new. > The fact that they have a different life cycle than > "harmless" cancer cells > appears to be new. As for the findings being not useful, > well maybe not yet. But I think this is a necessary step > to move to the next step (targeting treatments at the > cancer stem cells) so in the end I think it will be not > only useful but a necessary finding. > > Roger > There is no such thing as a "cancer stem cell" There are cells in a cancer which can't divide, many which can only divide a few times, then die, and a small proportion of cells which are "immortal" - I guess this is what you mean. But that is not new knowledge. The only cells likely to kill you are the immortal ones, and these are the cells targeted by radiation and chemo. The only cells responsible for recurrence are the immortal ones. The only real cancer cells are the immortal ones..................
"Steph" <[email protected]> wrote in message news:[email protected]... > > "Roger" <[email protected]> wrote in message news:0yd4c.345- > [email protected] > > > > "Steph" <[email protected]> wrote in message > > news:[email protected]... > > > > > > "Roger" <[email protected]> wrote in message news:O3d4c- > > > [email protected] > > > > At least according to the article below. Seems to > > > > completely change > the > > > > approach to dealing with cancer since the cancer > > > > stem cells don't have > a > > > > life cycle like cancerous non-stem cells. > > > > > > > > Roger > > > > > > > > > > It's been well established for 30 years that only a > > > small proportion of > > the > > > cells in a cancer are able to continually divide and > > > spread. In many sarcomas, the Cell Loss Factor is as > > > high as 99% So this is nothing new, and nothing useful What is new is the isolation of these cells. It may have been known before that there was a subset of such cells but it's only recently that the stem cell-like cancer cells in a human breast cancer were isolated from the other cancer cells and tested on mice. So this is new. It's why it was in the Proceedings of the National Academy of Sciences in 2003. And it's a breakthrough because these cells can be examined closely to see what is unique about them. If they are somewhat uniform, then it makes the job of finding effective therapies a lot easier compared to having to deal with a hundred (or whatever) radically different types of cancer cells due to mutations. > > > > The findings about the existence of the cancer stem > > cells appear to be > new. > > The fact that they have a different life cycle than > > "harmless" cancer > cells > > appears to be new. As for the findings being not useful, > > well maybe not yet. But I think this is a necessary step > > to move to the next step (targeting treatments at the > > cancer stem cells) so in the end I think it will be not > > only useful but a necessary finding. > > > > Roger > > > > There is no such thing as a "cancer stem cell" According to the researcher (Michael Clarke of the University of Michigan) who discovered last year the subset of breast cancer cells in a breast cancer tumor that act genuinely cancerous, these cells are stem cells in the sense that all cancer cells come from them. So these cancer stem cells produce daughter cancer stem cells as well as less dangerous cancer cells that are not cancer stem cells. Thus they play a role similar to normal stem cells in that all cells come from stem cells. > There are cells in a cancer which can't divide, many which > can only divide a > few times, then die, and a small proportion of cells > which are "immortal" - > I guess this is what you mean. But that is not new > knowledge. But what's new is the isolation of them and the testing of them in mice. The testing consisted of putting 100 of these cancer stem cells in the mice and a tumor would grow. Normally 100 cancer cells can not produce a tumor - about one million are needed. They also tested the non-stem cell cancer cells and none of them could produce a tumor no matter how many were injected into the mice. Thus all the mutations those cancer cells have undergone do not matter. This is why (if I understand this correctly) this discovery has the potential to make it a lot easier to kill a tumor. Now they can zero in on just those cells since they have them isolated now and see what will prevent them from making daughter cells and what will kill them. Roger The only cells > likely to kill you are the immortal ones, and these are > the cells targeted by radiation and chemo. The only cells > responsible for recurrence are the immortal ones. The only > real cancer cells are the immortal ones..................
"Roger" <[email protected]> wrote in message news[email protected]... > I've been in this game long enough to know you shouldn't hold your breath............
Steph <[email protected]> wrote: > "Roger" <[email protected]> wrote in message newseB4c.361- > [email protected] > > > > I've been in this game long enough to know you shouldn't > hold your breath............ . :-/ Speaking of which, you must be blue in the face waiting for that beer I owe you.. Now if you happen to be in Scotland again during the last week of March... (3 consultant posts up for grabs at the Beatson) you could breath easier again and enjoy a Kilkenny with us. If not, hold thumbs please.. -- Jon
"madiba" <[email protected]> wrote in message news:1gap9zf.1sxj4nm1gjhgjlN%[email protected]... > Steph <[email protected]> wrote: > > > "Roger" <[email protected]> wrote in message newseB4c.3- > > [email protected] > > > > > > > I've been in this game long enough to know you shouldn't > > hold your breath............ > . :-/ > > Speaking of which, you must be blue in the face waiting > for that beer I owe you.. Now if you happen to be in > Scotland again during the last week of March... (3 > consultant posts up for grabs at the Beatson) you could > breath easier again and enjoy a Kilkenny with us. If not, > hold thumbs please.. > -- > Jon That's 9 consultant posts up for grabs at the Beatson, Jon...........though they are only advertising 3 at a time. In fact, I'll let you into a secret...........I was "invited" to apply for the post of Director but when they saw my set of proposals for turning the place around, they decided not to short list me..... Was in the UK in Feb, and won't be back until next year sometime. Not thinking of a move to Bonny Scotland yourself, are you? Don't worry, the pint is in my PalmPilot spreadsheet......
Steph <[email protected]> wrote: > "madiba" <[email protected]> wrote in message > news:1gap9zf.1sxj4nm1gjhgjlN%[email protected]... > > Steph <[email protected]> wrote: > > > > > "Roger" <[email protected]> wrote in message newseB4c- > > > [email protected] > > > > > > > > > > I've been in this game long enough to know you > > > shouldn't hold your breath............ > > . :-/ > > > > Speaking of which, you must be blue in the face waiting > > for that beer I owe you.. Now if you happen to be in > > Scotland again during the last week of March... (3 > > consultant posts up for grabs at the Beatson) you could > > breath easier again and enjoy a Kilkenny with us. If > > not, hold thumbs please.. > > That's 9 consultant posts up for grabs at the Beatson, > Jon...........though they are only advertising 3 at a > time. In fact, I'll let you into a secret...........I was > "invited" to apply for the post of Director but when they > saw my set of proposals for turning the place around, they > decided not to short list me..... Was in the UK in Feb, > and won't be back until next year sometime. Not thinking > of a move to Bonny Scotland yourself, are you? I was, but if that means carring the workload of the missing 6 perhaps I should reconsider.. Prefer warmer climes normally so Portsmouth was where I aimed for - but a cute Finn beat me to the finish. -- Jon
"madiba" <[email protected]> wrote in message news:1gar2my.11d896w1h77vasN%[email protected]... > Steph <[email protected]> wrote: > > > "madiba" <[email protected]> wrote in message > > news:1gap9zf.1sxj4nm1gjhgjlN%[email protected]... > > > Steph <[email protected]> wrote: > > > > > > > "Roger" <[email protected]> wrote in message newseB- > > > > [email protected] > > > > ... > > > > > > > > > > > > > I've been in this game long enough to know you > > > > shouldn't hold your breath............ > > > . :-/ > > > > > > Speaking of which, you must be blue in the face > > > waiting for that beer I > > > owe you.. Now if you happen to be in Scotland again > > > during the last week of March... (3 consultant posts > > > up for grabs at the Beatson) you could breath easier > > > again and enjoy a Kilkenny with us. If not, hold > > > thumbs please.. > > > > That's 9 consultant posts up for grabs at the Beatson, Jon...........though > > they are only advertising 3 at a time. In fact, I'll let > > you into a secret...........I was "invited" to apply for > > the post of Director but when they saw my set of > > proposals for turning the > > place around, they decided not to short list me..... Was > > in the UK in Feb, and won't be back until next year > > sometime. Not thinking of a move to Bonny Scotland > > yourself, are you? > I was, but if that means carring the workload of the > missing 6 perhaps I should reconsider.. Prefer warmer > climes normally so Portsmouth was where I aimed for - but > a cute Finn beat me to the finish. > -- > Jon No shortage of Clinical Oncology jobs in the BMJ. There are about 60+ unfilled consultant posts in the UK
On Fri, 12 Mar 2004 16:03:52 GMT, Steph <[email protected]> wrote: > > "Roger" <[email protected]> wrote in message news:0yd4c.345- > [email protected] >> >> "Steph" <[email protected]> wrote in message >> news:[email protected]... >> > >> > "Roger" <[email protected]> wrote in message news:O3d4c.- >> > [email protected] >> > > At least according to the article below. Seems to >> > > completely change > the >> > > approach to dealing with cancer since the cancer stem >> > > cells don't have > a >> > > life cycle like cancerous non-stem cells. >> > > >> > > Roger >> > > >> > >> > It's been well established for 30 years that only a >> > small proportion of >> the >> > cells in a cancer are able to continually divide and >> > spread. In many sarcomas, the Cell Loss Factor is as >> > high as 99% So this is nothing new, and nothing useful >> >> The findings about the existence of the cancer stem cells >> appear to be > new. >> The fact that they have a different life cycle than >> "harmless" cancer > cells >> appears to be new. As for the findings being not useful, >> well maybe not yet. But I think this is a necessary step >> to move to the next step (targeting treatments at the >> cancer stem cells) so in the end I think it will be not >> only useful but a necessary finding. >> >> Roger >> > > There is no such thing as a "cancer stem cell" There are > cells in a cancer which can't divide, many which can only > divide a few times, then die, and a small proportion of > cells which are "immortal" - I guess this is what you > mean. But that is not new knowledge. The only cells likely > to kill you are the immortal ones, and these are the cells > targeted by radiation and chemo. The only cells > responsible for recurrence are the immortal ones. The only > real cancer cells are the immortal ones.................. And do the assays for drug activity differentiate between the 'immortal' ones and the others? I would tend to doubt so, and this means that many of the treatment strategies might be going against the wrong cell populations.
"Dr Chaos" <[email protected]> wrote in message news:[email protected]... > On Fri, 12 Mar 2004 16:03:52 GMT, Steph > <[email protected]> wrote: > > > > "Roger" <[email protected]> wrote in message news:0yd4c.3- > > [email protected] > >> > >> "Steph" <[email protected]> wrote in message > >> news:[email protected]... > >> > > >> > "Roger" <[email protected]> wrote in message news:O3d4- > >> > [email protected] > >> > > At least according to the article below. Seems to > >> > > completely change > > the > >> > > approach to dealing with cancer since the cancer > >> > > stem cells don't have > > a > >> > > life cycle like cancerous non-stem cells. > >> > > > >> > > Roger > >> > > > >> > > >> > It's been well established for 30 years that only a > >> > small proportion of > >> the > >> > cells in a cancer are able to continually divide and > >> > spread. In many sarcomas, the Cell Loss Factor is as > >> > high as 99% So this is nothing new, and nothing > >> > useful > >> > >> The findings about the existence of the cancer stem > >> cells appear to be > > new. > >> The fact that they have a different life cycle than > >> "harmless" cancer > > cells > >> appears to be new. As for the findings being not > >> useful, well maybe not > >> yet. But I think this is a necessary step to move to > >> the next step (targeting treatments at the cancer stem > >> cells) so in the end I think it > >> will be not only useful but a necessary finding. > >> > >> Roger > >> > > > > There is no such thing as a "cancer stem cell" There > > are cells in a cancer which can't divide, many which > > can only divide a > > few times, then die, and a small proportion of cells > > which are "immortal" - > > I guess this is what you mean. But that is not new > > knowledge. The only cells > > likely to kill you are the immortal ones, and these are > > the cells targeted > > by radiation and chemo. The only cells responsible for > > recurrence are the > > immortal ones. The only real cancer cells are the > > immortal ones.................. > > And do the assays for drug activity differentiate between > the 'immortal' ones and the others? No. But the immortal ones ( clonogenic cells) for many cancers can be grown indefinitely in vitro. Ever heard of HeLa cells? Very commonly used for cancer experimentation, and all derived from a single cancer patient 20+ years ago. Still going strong. > > I would tend to doubt so, and this means that many of the > treatment strategies might be going against the wrong cell > populations. > Just because in vitro assays don't work doesn't mean that the clonogenic cells in a cancer aren't the culprits
On Wed, 07 Apr 2004 01:57:53 GMT, Steph <[email protected]> wrote: > > No. But the immortal ones ( clonogenic cells) for many > cancers can be grown indefinitely in vitro. Ever heard of > HeLa cells? Very commonly used for cancer experimentation, > and all derived from a single cancer patient 20+ years > ago. Still going strong. Good. Now what if they have characteristics unlike spontaneous human cancers? In particular the minority of human cancer stem cells. >> >> I would tend to doubt so, and this means that many of the >> treatment strategies might be going against the wrong >> cell populations. >> > > Just because in vitro assays don't work doesn't mean that > the clonogenic cells in a cancer aren't the culprits I think we're in agreement. I think that this new result actually is big news, and ought to seriously change the nature of cancer research. Tumor shrinkage means little if it shrinks the wrong 97% of the cell population.
"Dr Chaos" <[email protected]> wrote in message news:[email protected]... > On Wed, 07 Apr 2004 01:57:53 GMT, Steph > <[email protected]> wrote: > > > > No. But the immortal ones ( clonogenic cells) for many > > cancers can be grown indefinitely in vitro. Ever heard > > of HeLa cells? Very commonly used for cancer > > experimentation, and all derived from a single cancer > > patient 20+ years ago. Still going strong. > > Good. Now what if they have characteristics unlike > spontaneous human cancers? In particular the minority of > human cancer stem cells. > He La is a spontaneous human cancer cell line......... > >> > >> I would tend to doubt so, and this means that many of > >> the treatment strategies might be going against the > >> wrong cell populations. > >> > > > > Just because in vitro assays don't work doesn't mean > > that the clonogenic cells in a cancer aren't the > > culprits > > I think we're in agreement. > > I think that this new result actually is big news, and > ought to seriously change the nature of cancer research. > > Tumor shrinkage means little if it shrinks the wrong 97% > of the cell population. Sensible oncologist have known that (and been saying it) for years What is more, by the time a cancer is 1cm in size, it is 3/4 of the way to being 1kg in size............ The "New result" isn't new, and isn't a result. Don't get too excited
On Sat, 10 Apr 2004 23:32:34 GMT, Steph <[email protected]> wrote: >> I think that this new result actually is big news, and >> ought to seriously change the nature of cancer research. >> >> Tumor shrinkage means little if it shrinks the wrong 97% >> of the cell population. > > Sensible oncologist have known that (and been saying it) > for years What is more, by the time a cancer is 1cm in > size, it is 3/4 of the way to being 1kg in > size............ > > The "New result" isn't new, and isn't a result. Don't get > too excited The question is whether the therapies preferentially kill the 97% of the wrong cells, since they were probably assayed in drug development by tumor shrinkage. IF they had a way to assay "%age kill of tumor stem cells" perhaps the drugs would be far different.
"Dr Chaos" <[email protected]> wrote in message news:[email protected]... > On Sat, 10 Apr 2004 23:32:34 GMT, Steph > <[email protected]> wrote: > >> I think that this new result actually is big news, and > >> ought to seriously change the nature of cancer > >> research. > >> > >> Tumor shrinkage means little if it shrinks the wrong > >> 97% of the cell population. > > > > Sensible oncologist have known that (and been saying it) > > for years What is more, by the time a cancer is 1cm in > > size, it is 3/4 of the way to > > being 1kg in size............ > > > > The "New result" isn't new, and isn't a result. Don't > > get too excited > > The question is whether the therapies preferentially kill > the 97% of the wrong cells, since they were probably > assayed in drug development by tumor shrinkage. > > IF they had a way to assay "%age kill of tumor stem cells" > perhaps the drugs would be far different. Paradoxically, it is actually the clonogenic cells (your stem cells) which are the most sensitive to radiation and chemotherapy.....
