[Cell-biology] Re: Animations of a Possible Cure for Cancer

John via cellbiol%40net.bio.net (by jmcgowan79 from gmail.com)
Fri Nov 11 18:10:48 EST 2011


On Nov 8, 2:34 pm, PiLS <p... from invalid.ca> wrote:
> Le lun, 07 nov 2011 17:46:37, John a ploppé:
>
> > Animations of a Possible Cure for Cancer
>
> > This is an approach to the cure or treatment of cancer using a
> > relatively simple mathematical algorithm.
>
> >http://math-blog.com/2011/10/31/animations-of-a-possible-cure-for-can...
>
> That is a nice animation but has little to no merit as far as curing
> cancer goes. Not all cancer cells are aneuploid, nor is every normal
> cell diploid. Bacteriophages target bacteries, not mamalian cells,
> although it would be possible to find another vector, like a lentivirus.
> But in that case it would be much easier to target only cancer cells
> based on the surface receptor they display. Which, surprise surprise,
> is already being studied.
> The surface recognition strategy is also used by our own immune
> system to eliminate most cancer cells (some escape from time to time),
> or in therapeutic strategies based on autologous immune cells modified
> to kill the (escaped) cancer cells -already in use.
>
> The problem with using a virus is that it usually triggers the immune
> response, which can lead, in the best case scenario, to the destruction
> of the therapeutic vector, and in the worst case, to very toxic effects.
>
> Basing the system on the number of chromosome is typically a bad idea as
> exposed higher (this is a common mistake: most cancer cells are aneuploid,
> so let's kill all the non-diploid cells. Cancer cured. It amounts to
> Most cancer cells are alive, so let's kill all live cells, cancer cured.)
> Not to mention that it would be extremely difficult to "automatically"
> count the number of chromosomes. Telomeres and centromeres vary in size
> and "geometry" between cell types, depending on the age, etc...
>
> As I said, that's a nice animation.
>
> --
> PiLS

As the article indicates, the presentation is simplified and a number
of technical difficulties are omitted to present the basic concept of
how one might successfully "count" the number of chromosomes and kill
cells with the wrong number of chromosomes.

For example, in the actual system, the non-toxic precursor might be
engineered to react specifically with the end of the telomeres since,
indeed, they vary in length by many accounts.  A telomere is
supposedly constructed of repeating DNA sequences, e.g.

(repeat)(repeat)(repeat)(repeat)...(repeat)(repeat)(repeat)(end of
DNA)

so one might engineer the precusor to target the end pattern:

(repeat)(repeat)(repeat)(end of DNA) only.

or some other solution.  Something similar may be possible with the
centromeres or other commonly recognized features of the chromosomes.
As with the telomeres, the edge of a commonly recognized feature may
be constant even though the size and geometry of the feature varies.

Red blood cells have no chromosomes, so the system would generate no
toxins in the red blood cells.  Terminally ill persons probably would
be willing to sacrifice their sperm or ova if some way to protect
these cells, which lack the normal number of chromosomes, could not be
found.  Osteoblasts and muscle cells reportedly have multiple nuclei,
so in the real system one would like the drains to reach or be a
natural part (preferred) of the nucleus and perform the selective
destruction operation, the bathtub mechanism, inside the nuclear
membrane so cells with multiple normal nuclei would survive.

The implementation of this system is technically advanced, so one
would be talking about modifying the bacteriophages to work with human
cells or using lentiviruses or some other mechanism of introducing the
drains into the cells.  It would be better to find a constant feature
that is present in the cells naturally and could be used as the drain.

Yes, cancer researchers have been trying to use receptors on the
exterior of cancer cells for some time to cure or treat the disease,
with dismal results in the real world.  The same could be said of
attempts to harness the immune system.  So, instead, the article
presents a different approach that hasn't been tried and failed many
many times.

The relationship between aneuploidy and cancer is unclear, as the
article clearly states.

I am not a biologist and I would urge biologists with specific
expertise to think about how to implement the illustrated algorithm in
a real system using real cellular and molecular building blocks,
viruses, and other components that we have knowledge of.


Sincerely,

John






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