Posted on 02/27/2005 12:54:54 PM PST by Paleo Conservative
Cancer drugs have unexpectedly led to an entirely new way to beat viral infections - and particularly smallpox - a new study suggests.
Viruses are hard to stop and, with few exceptions, drugs aimed at killing viral infections have not worked nearly as well as the antibiotics that kill bacteria.
Now, US scientists have found that an experimental drug aimed at stopping the uncontrolled growth of cancer cells actually prevents the smallpox virus from replicating inside human cells, and can save mice from dying of a closely related virus, Vaccinia.
Viruses succeed by invading a cell and hijacking the "machinery" used by actively dividing cells to replicate their own DNA. But most cells frequently exposed to viruses - such as skin cells or those lining the lungs - are not actively dividing and so have their replication machinery turned off. Viruses such as smallpox have learned to turn it back on by making their own copies of the hormones and growth factors that normally induce cells to divide.
Since the overexpression of the receptors for these growth factors in cancer cells is one of the reasons cancers grow uncontrollably, cancer research has focused on finding molecules that block the receptors. Preventing infection
Ellis Reinherz and colleagues at the Dana Farber Cancer Institute in Boston, US, had already discovered that smallpox and its relatives produce molecules similar to the growth factors naturally produced by the body to signal these very same receptors, called erb-B1. They use these factors to turn their host cell's replicating machinery on.
"We reasoned that if the viral factor's stimulatory activity was blocked, then viral growth might be curtailed," say the researchers. They used an experimental cancer drug to block the erb-B1 receptor, and found that this did indeed stop the smallpox virus from propagating in human cells in culture.
The team then gave the drug to mice and infected them with Vaccinia. The drug saved all the treated mice from dying at doses of virus that killed all of the untreated mice.
It worked even better when combined with an antibody highly specific for Vaccinia. And the combined approach was better than the added effects of each separately, possibly because they strongly stimulated the mouse's own immune response. Human infections
One drawback, Reinherz notes, is that the mouse treatment only worked if the drug was given before the virus. Although treating the mouse after the viral infection began did reduce the severity of infection the mice still died. The authors suspect that in a slower-developing disease, as pox infections are in humans, the combined treatment might have a better chance of beating the virus.
The real advantage, though, is that this approach does not target the virus itself - it targets the machinery, or signalling pathway, of the host cell, which the virus hijacks. Like bacteria and antibiotics, viruses evolve resistance to antiviral drugs that are aimed at the virus's own components.
"The advantage of targeting signalling pathways is that cells are far less likely to mutate than the viruses themselves, making it improbable that drugs will lose their potency," says Reinherz.
Journal reference: Journal of Clinical Investigation (DOI: 10.1172/JCI200523
Cancer, I always find it strange when they say "Cancer kills" when the fact of the matter is it`s nothing more than cells that replicate too fast for the body to contain. Like a damn breaking and a river smashes into town. What ever happened to that drug they were working on that cut off the blood supply to fast replicating cells specifically? Cancer does not live unless it gets oxegen and nutrients, surely there must be a way to coat these cells with a substance that is attracted to these types of cells, a substance that "suffocates" them. Like oil and water repel, surely there must be the opposite. We are made of something like 75% water and if some cell is freaking out and breeding every two seconds like a clinic of welfare breeding cows around Bill Clinton, surely these cells can be isolated with chemical targets and suffocated! Why is this so hard to cure? It`s not a virus, it`s a freggin mutated cell. We don`t want to save the cell, the cell freaks out then coat it in rubber!
Capillaries, exactly, this is what I was talking about. I compare cancer cells to seedlings in the ground. If you ever put a seed in a glass cup as a kid, you see the tiny roots forming first. The fact is, is that cancer cells do the same thing. They are allowed to grow and grow. Their speed at growing is what kills, but if you think about it, speed would not matter at all if they were targeted and wiped out the second they were identified as "different". I don`t understand why this is impossible to solve.. If the average cell growth rate was taken in a section of the human body, why is it impossible to direct poison to those cells that take in more nutrients than others? Cancer cells eat up a hell of a lot more food that regular cells, so why can`t they be targeted? I swear, I hate to sound like a nut, but I am highly suspicious that this disese is not being solved solely to keep drug companies in the green, keep them profitable. To cure one cancer patient eliminates 10`s of thousands of dollars per year of profit to these companies. Cancer to me seems so damn simple, it doesn`t make sense to me why it can`t be beaten.
"Cancer to me seems so damn simple, it doesn`t make sense to me why it can`t be beaten."
In that case, maybe you should cure cancer, get the Nobel Prize, make a trillion dollars, buy Hawaii, and retire.
Thalidomide, made by New Jersey based Celgene (Nasdaq, CELG).
Amazing set of pictures. Keep it handy - we may need it in 2008.
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