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How can knocking out a certain gene (for all cells in your body) kill a cancer cell? For instance, for many cancer cells with a defect in 'P53' (a gene which ca

by jstsch 13y ago

How can knocking out a certain gene (for all cells in your body) kill a cancer cell? For instance, for many cancer cells with a defect in 'P53' (a gene which can induce cell death), knocking out this defective gene would not help - would it? Or would you need a two step process, like a molecule which connects to the marker and then use a second step to knock-out a gene essential for cell survival? Or can this technique be used to repair a certain gene?

toufka 13y ago
The most interesting part of the above tool is not its ability to knock out a specific gene, but its ability to knock out a specific gene. The key word is 'specificity'. Knocking out is just the easiest proof of principle thing you can do once you find a sequence. Finding it with specificity in a live organism is the magnificent part. There is an entire field dedicated to editing genetic code - and it's getting really good. The issue is targeting it to the right spot in a live organism (and conversely, not targeting your editing machinery to the wrong spot). If you can get to it, there's lots you can do besides knocking out a gene. If we call the p53 gene the judge or head executioner in our scheme above, it's finding him that's the problem. If you can pinpoint the corrupt judge, you can easily (relative to finding him) install a replacement. What you don't want to do is accidentally replace your police force or your teachers with judges/executioners (even if they're good ones) - and that ability to target is the greatest issue with engineering the genetics of live cells currently. (As a side note, this is EXACTLY what the HPV virus does - it runs around assassinating that judge with relentless precision - and thus is a prime cause for allowing cancer to run rampant. The vaccine against HPV prevents these assassinations.) Further, and only slightly more in the future, once you have access to the genetics, you can start to run logic programs inside the cells. You can start to release the (genetically encoded) tools IFF the cell is $cancerous, where $cancerous is defined as a further set of genetic conditions within the cell. In this way you could surveill the entire society while only targeting the bad guys.
- jstsch 13y ago
  Right! I wasn't aware that the editing process is quite easy once you can target a specific gene. Awesome! :)
  - mbreese 13y ago
    Specifically, you can target just the defective version of the gene. In theory, your good copies could be ignored, only removing the bad genes from the cancer tissue. However, I don't think that this will ever be applied on a whole-body scale because the off-target effects aren't well characterized at this point. That is, of course, unless you have a bad cancer and have no other options. At that point, having off-target effects is the least of your concerns. The problem with gene editing in this context is that the changes are permanent. So if you miss and edit a good cell, that cell is now damaged, or may only have 1 good copy of a gene, and thus be more susceptible in the future. In some cases, shRNA to silence a gene may prove more effective because it is temporary. Right now these are only used in the lab for research.

by jstsch 13y ago

toufka 13y ago

The most interesting part of the above tool is not its ability to knock out a specific gene, but its ability to knock out a specific gene. The key word is 'specificity'. Knocking out is just the easiest proof of principle thing you can do once you find a sequence. Finding it with specificity in a live organism is the magnificent part. There is an entire field dedicated to editing genetic code - and it's getting really good. The issue is targeting it to the right spot in a live organism (and conversely, not targeting your editing machinery to the wrong spot). If you can get to it, there's lots you can do besides knocking out a gene. If we call the p53 gene the judge or head executioner in our scheme above, it's finding him that's the problem. If you can pinpoint the corrupt judge, you can easily (relative to finding him) install a replacement. What you don't want to do is accidentally replace your police force or your teachers with judges/executioners (even if they're good ones) - and that ability to target is the greatest issue with engineering the genetics of live cells currently. (As a side note, this is EXACTLY what the HPV virus does - it runs around assassinating that judge with relentless precision - and thus is a prime cause for allowing cancer to run rampant. The vaccine against HPV prevents these assassinations.) Further, and only slightly more in the future, once you have access to the genetics, you can start to run logic programs inside the cells. You can start to release the (genetically encoded) tools IFF the cell is $cancerous, where $cancerous is defined as a further set of genetic conditions within the cell. In this way you could surveill the entire society while only targeting the bad guys.

jstsch 13y ago
Right! I wasn't aware that the editing process is quite easy once you can target a specific gene. Awesome! :)
- mbreese 13y ago
  Specifically, you can target just the defective version of the gene. In theory, your good copies could be ignored, only removing the bad genes from the cancer tissue. However, I don't think that this will ever be applied on a whole-body scale because the off-target effects aren't well characterized at this point. That is, of course, unless you have a bad cancer and have no other options. At that point, having off-target effects is the least of your concerns. The problem with gene editing in this context is that the changes are permanent. So if you miss and edit a good cell, that cell is now damaged, or may only have 1 good copy of a gene, and thus be more susceptible in the future. In some cases, shRNA to silence a gene may prove more effective because it is temporary. Right now these are only used in the lab for research.