Cell Question

[pljames]

Is it possible to either inject the bad cell with a antiagent or a kill the bad guy agent. It would seem logical if the disease comes from the original cell a cure can also be found in the cell lever? pljames

[Skye]

I think you're going to have to explain what you mean more clearly for people to be able to answer you.

[newty]

If we could do that, then we could stop cancer in its tracks! It is a hard task to microinject solutions into a single cell in vitro (I know because I do this for my current project), yet alone try to microinject a substance in vivo. It is too difficult, if not almost impossible. It is possible to inject into a single cell in vivo, but identification of the cell(s) is another matter altogether. Most assays are done in vitro or ex vivo (usually fixed).

 

Newty

[daisy]

Cancer is a disease that has many forms, so to cure it you need a different "anti-agent" as you call it for each form. Some cancers are age-related, others are not, each occurs via a different pathway. I totally doubt that one magic bullet will cure all cancers. That is why despite many millions of dollars/pounds being funneled into cancer research each year there has been no "cure" for cancer. Indeed you could argue that this money might be better spent researching diseases we know might give a better "return" but are sidelined for the more politically correct diseases such as cancer. Sorry to be cynical but that's the way it is.

[Dak]

in theory, you could use viral vectors. a hiv based vector, for example, could inject stuff into all cd4+ cells, what with hiv being desighned specifically to infect cd4+ cells.

 

So, if the target cells exhibit some unique cell membrane structure that a virus targets, then they can be targeted by viral-vector delivered chemicals.

 

but in practice its a lot trickier than that, apparently.

[zyncod]

Well, the thing is with cancers is that they're your own cells, so you can't really attack them head-on without killing yourself too. And, yes, every cancer researcher will tell you that there will never ever be a cure for cancer. You can't stop evolution.

[Xyph]

I think saying there will "never ever be a cure for cancer" might be a bit excessive... I don't know quite what the current consensus on the plausibility of this is, but it seems that nanobots could be employed to target and deconstruct cancer cells, which would be a potential cure-all - presumably there are some criteria that could be used by the nanobots to differentiate between cancer cells and noncancerous ones. More speculatively, surely there will come some sort of genetic engineering that could be employed to significantly reduce or eliminate the risk of cancer? I know it would be difficult, but I can't believe there's absolutely no way to implement some sort of inbuilt anticancer protection. A biological version of the aforementioned cancer-targetting nanobots would work well, wouldn't it?

 

You can't stop evolution.

Hmm, what do you mean by this? I don't see how being prone to cancer is at all evolutionarily advantageous.

[zyncod]

Cancer is evolution - within your body. There's a number of safeguards that any cell must outevolve to become cancerous - like contact inhibition. All any drugs or nanobots are going to do is increase the number of safeguards that a cell must outevolve - from six to seven, or eight, or one hundred. At some point, the cancer is going to outevolve these safeguards. Cancer is not curable the way a disease from a pathogen is curable because your cells are the "pathogen" - albeit quiescent for the vast majority.

[LucidDreamer]

And, yes, every cancer researcher will tell you that there will never ever be a cure for cancer.

I can't speak for every cancer researcher, but I believe there will be a "cure" for cancer. Our chemotherapies become more efficient and less toxic every year. We will continue to become more knowledgeable about alternative therapies. New kinds of biotherapies will be invented. We will continue to become more knowledgeable about the viruses that cause cancer. There will be a point in time when we will be able to remove oncogenes and other genes that predispose people to cancer from the gene pool. With billions of people on the earth we will discover genes/alleles in people that have remarkable properties to fight off cancer that we can increase in frequency of through selection or recombination. Most of the treatments that we consider cures are not 100% successful, so I believe that we will reach a state when we will have cancer so well under control that we might consider it cured by the same standards.

[rakuenso]

in theory' date=' you could use viral vectors. a hiv based vector, for example, could inject stuff into all cd4+ cells, what with hiv being desighned specifically to infect cd4+ cells.

 

So, if the target cells exhibit some unique cell membrane structure that a virus targets, then they can be targeted by viral-vector delivered chemicals.

 

but in practice its a lot trickier than that, apparently.[/quote']

 

One example of its trickiness is a French trial treatment of SCID with viral vectors, one of the children developed a form of leukemia that has never been seen before

[ashennell]

Cancer is evolution - within your body. There's a number of safeguards that any cell must outevolve to become cancerous - like contact inhibition. All any drugs or nanobots are going to do is increase the number of safeguards that a cell must outevolve - from six to seven, or eight, or one hundred. At some point, the cancer is going to outevolve these safeguards. Cancer is not curable the way a disease from a pathogen is curable because your cells are the "pathogen" - albeit quiescent for the vast majority.

 

I'm sure if I agree with this completely.

 

Cancer could be viewed as evolution where selection unit is the cell and not the gene. I agree here. Mututions required for cells to become cancerous must build up in an individuals lifetime and therefore increasing the number of safeguards should dramamatically reduce the occurence. Each safeguard being overcome by a chance mutation.

 

However, with pathogenic disease, the bacteria of virus continues to evolve over generations. This means that vaccines that are effective may become uneffective in the future. This seems more dangerous to me and possibly harder problem to solve in the long term. Once we are able to target cencerous cells specifically I think we should be able to effectively 'cure' cancer. I know that there is not one single type of cancer cell so identification may be difficult. But at least resistance to treatment will not be passed on to other individuals.

[lucaspa]

I think saying there will "never ever[/i'] be a cure for cancer" might be a bit excessive...

Maybe, but Zynod's point is that cancer is not a single disease or cellular defect, but a number of diseases and cellular defects that have similar results. So it is unlikely to be a SINGLE cure for all cancers.

 

In the last 20 years, I have seen what appeared to be cures. However, both failed because of natural selection. Each cancer cell is a little bit different because they accumulate changes in the genome. So, a treatment will kill 99.99% of the cells and reduce the tumor to invisibility on MRI or CAT scan. However, a few cells survive and begin dividing again. Soon the entire population of tumor cells has come from cells immune to the treatment.

 

Natural selection in action.

 

Hmm, what do you mean by this? I don't see how being prone to cancer is at all evolutionarily advantageous.

When do the vast majority of cancers occur? After you have had children! Therefore, being cancer prone is not visible to natural selection.

[lucaspa]

Cancer could be viewed as evolution where selection unit is the cell and not the gene.

In evolution, the selection unit is always the individual. Not a single gene. It is the individual who survives and reproduces, not the gene.

 

Once we are able to target cencerous cells specifically I think we should be able to effectively 'cure' cancer. ... But at least resistance to treatment will not be passed on to other individuals.[/

But, when each cancer cell is a little different from all the other cancer cells, how do you target each and every cell? Whatever you use for the target, there will be one or two cells (out of the billions in the tumor) that don't have that target. So, you still have 1 or 2 survivors, who then divide and make the tumor all over again. And now the new tumor is immune to your treatment.

 

Yes, the problem is exactly that resistance will be passed on to new cells. In this case, the cell is the "individual".

[ashennell]

In evolution, the selection unit is always the individual. Not a single gene. It is the individual who survives and reproduces, not the gene.

 

This is not true. The unit that is selected is the gene not the individual. that is why some evolutionary stategies will result in the sacrifice of an individual if, overall, more copies of the genes are likely to survive.

 

But, when each cancer cell is a little different from all the other cancer cells, how do you target each and every cell? Whatever you use for the target, there will be one or two cells (out of the billions in the tumor) that don't have that target. So, you still have 1 or 2 survivors, who then divide and make the tumor all over again. And now the new tumor is immune to your treatment.

 

However, the mutations required to produce cancerous cells can only be certain ones. just any old combination of mutations does not result in cancer. Therefore there is a limited number of possible mutations that need to be detectable. I'm not saying that targetting cancereus cells would be easy mind you.

 

Yes, the problem is exactly that resistance will be passed on to new cells. In this case, the cell is the "individual".

 

Yes, but not on to different individuals therefore solutions that we come up with should always be effective. not like current antibiotics. This was my point.

[lucaspa]

This is not true. The unit that is selected is the gene not the individual. that is why some evolutionary stategies will result in the sacrifice of an individual if, overall, more copies of the genes are likely to survive.

Dawkin's tried to promote the gene as the selection UNIT, but that is not true. The selection unit is always the individual, the package of genes. Single genes don't sacrifice themselves, individuals do. Yes, altruism can be explained because more packages of genes survive, and those packages will tend to contain the genes that program sacrifice. What you have above is the simplistic version of what happens.

 

However, the mutations required to produce cancerous cells can only be certain ones. just any old combination of mutations does not result in cancer. Therefore there is a limited number of possible mutations that need to be detectable. I'm not saying that targetting cancereus cells would be easy mind you.

For cancer, checks on proliferation must be removed. That is, the cell moves through the cell cycle without ever being stopped. However, there are a number of genes involved in the cell cycle and the interaction of these genes have permutations that run into the millions. One common way for cancer is to have a mutation in p53. However, even if p53 is normal or is knocked out entirely, there are a least a dozen known ways to get around this.

 

Also, abnormal cells undergo apoptosis. There are at least 2 dozen proteins involved in the process and double that number of proteins that can influence whether apoptosis occurs or is stopped. Again, the permutations run into the millions.

 

So, targeting one gene product or even two or three is not going to solve the problem. There is (nearly) always going to be a cell that can get around what is blocked.

 

Cancer also involves some other processes such as avoidance of the immune system and a way of inducing angiogenesis. One of the cures I saw in the 1980s involved filtration of the blood. It turns out that cancers produce soluble tumor necrosis factor (TNF) receptor that binds TNF in the blood. TNF is necessary to activate natural killer cells -- which kill cancer cells. So the researchers simply ultrafiltered the blood and removed all proteins below 30,000 MW. That got rid of the soluble TNF receptor. The results were dramatic. I saw a CAT scan of one patient where he had 10 nodules of lung cancer spread between both lungs. All gone. Five years later the nodules were back. Why? Because some few cells had another way to avoid being killed by natural killer cells.

 

Cancers are rare because a cell must have several mutations in several areas: cell cycle control, apoptosis pathways, angiogenesis, immunogenicity, ability to get out of the blood stream (for metastases), etc. By the time a cell has accumulated enough random mutations to meet all of these requirements it has also accumulated a lot of mutations in other systems, thus allowing it to avoid a single treatment strategy or chemical.

 

Now, one way oncologists are trying to avoid this is to use combinations of 2-3 different treatments at once. Where a cell may be invulnerable to one drug, it probably will not be invulnerable to 2 or 3.

 

Yes, but not on to different individuals therefore solutions that we come up with should always be effective. not like current antibiotics. This was my point.

Yes, methotrexate will kill cancer cells in both you and I. Unlike penicillin if we are infected with a penicillin resistant strain.

 

However, that is not important. We are not trying to kill a foreign invader. We are trying to kill each and ever cancer cell. And methotrexate will not kill each and every cancer cell. It is the cancer cells that are the threat, not bacteria. So yes, we can't pass on resistant cancer cells to a new individual. But who cares? It's our own cells that are going to kill us, so it is the resistance in individual cancer cells that concerns us.

 

 

 

Yes, but not on to different individuals therefore solutions that we come up with should always be effective. not like current antibiotics. This was my point.