[paul.fr]

Present thinking is that cancer is a genetic mutation (i think), but could it actually be a gene in it's own right? Say a gene that hides itself among other genes, thus causing the mutation?

[stana]

Im not really 100% sure on this.

But you develop cancer when one of your cells isnt put through a proces (when it dies) to be taken away (to make bile i think, but i think thats just RBC), This cell then multipliesl, hence causing a specific area to be cancerous

But as i say, im not 100% sure on this answer, im mixing school work with wiki work hehe

[stana]

Here we go    Quote from wikipedia

Cancer is a group of diseases in which cells are aggressive (grow and divide without respect to normal limits), invasive (invade and destroy adjacent tissues), and sometimes metastatic (spread to other locations in the body). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited in their growth and do not invade or metastasize (although some benign tumor types are capable of becoming malignant). Cancer may affect people at all ages, even fetuses, but risk for the more common varieties tends to increase with age. Cancer causes about 13% of all deaths. Apart from humans, forms of cancer may affect other animals and plants.


When normal cells are damaged beyond repair, they are eliminated by apoptosis.  Cancer cells avoid apoptosis and continue to multiply in an unregulated manner.

[another_someone]

I would argue that cancer is not actually a disease, it is a symptom (rather like a fever), and the causes can be many.

Some cancers are clearly partly caused by viruses (although again, it is normal that a virus that causes cancer in one patient, may do no such thing in another).  It seems quite plausible to me that cancers can be caused as collateral damage in the war between a virus and the anti-viral response of the human body.

It is mentioned above that cancers occur when cells fail to commit suicide when they should.  Apoptosis is a means by which the body can quarantine a cell that is infected by a virus, and thus it makes sense for the virus to try and switch off, or damage, the processes by which apoptosis might occur.

[HeLa]

Aren't a lot of cancers caused by the absence of tumor-suppresser proteins, such as p53, during mitosis? 

[manicgeek]

Cancer cells are just faulty cells.

Nearly every cell reproduces new cells (copies of itself), when a cell produces a faulty copy the cell reproductive cycle is supposed to be suspended, and in time the cell (which is now failing to manufacture good copies) will die it's natural death without causing any problems.

A cancerous cell is one where the cell reproduction suspend function fails, thus allowing faulty copies of cells to be produced which in turn may well produce more copies of themselves (all faulty).

We believe that p53 triggers the cell reproduction suspend function when a faulty cell copy is detected, and that p400 is also in some way responsible for this process.

Hence a failure to make an accurate copy, combined with a failure of the reproductive cycle suspend function, is what causes cancer... which may be as a result of p53 failing to prevent the faulty cell reproducing... then again it may be something else entirely  []

[MayoFlyFarmer]

paul, not 100% sure what you were asking in your original question; but hopefully this will help shed some light:

cancer occurs when a cell takes on properties that allow it to divide out of control and cross tissue planes.  by definition, any cell/group of cells that does this would be considered cancer whether there was any mutation or not.  however, there is no way for cells to take on these properties (that we know of, or at least that i can think of) that would cause a cell to change its physiological properties other than some sort of genetic change.  This genetic change, though, can occur in countless different ways.  The most common way that people think of, as you pointed out, is by a simple point mutation in a gene or genes; that causes that gene to be transcribed and produce its corosponding protein more, or less, or not at all; or to produce an altered form of that protein, or a compltely different protein.  Another type of genetic change that can occur is by the insertion of new genetic material.  This material could come either from a different part of your own genome that just moved to a new place for whatever reason, or could be introduced by an outside vector such as a virus.  This new genetic material could be placed near or in the middle of an existing gene and would cause the same effect on that gene as I described for a point mutation above; or it could be a whole gene in itself that gets introduced into the genome.

Now whether a new gene is introduced, or an existing gene is affected somehow, that gene has to affect (eithetr dirrectly, or indirrectly through a chain reaction involving other genes) some process that makes the cell take on the properties that I said make a cell "cancerous".  There are many genes in the human genom that have been found to be important in cancer.  a few of which have been named by other posters on this thread already, but more and more of them are being discovered by reserahcers all the time.

i know this is a lot of information.  hopefully its at leats relatively clear.  if i didn't even come close to answreing your question, feel free to try and re-phrase it and i'll take another stab.  this is the area that i do my research in, so i'm always glad to try and help someone undrestand what we know about the subject.

[chris]

Thanks Justin, that's an excellent synopsis. One point I could add is that some cancers are the product of a single mutation; that is, a single gene is altered and this transforms the cell; I suppose this could be akin to what Paul was suggesting that cancer could be a "gene". however, such cancers are extremely rare.

Another possiblity, that scientists are looking into, is the possibility that cancers could be transposons. These are mobile pieces of genetic material (e.g. DNA) that have the ability to insert themselves into another cell's genome. Some scientists have suggested that some of the spread of cancer around the body might be triggered by the primary tumour releasing pieces of DNA that can invade cells in other tissues and, by inserting itself into the genomes of these cells, destabilise them and trigger malignancy. I'm not sure if there's any evidence for this phenomenon, but I'll check it out. I'd say this is the closest analogy to Paul's "cancer gene" suggestion.

Chris

[MayoFlyFarmer]

wow, that's cool chris.  i've never heard of transposons jumping from one cell to another.  i'll have to read up on that.  makes sense though.  gets around the problem of "how does one little cell" create a whole tumor before the body realizes what's going on and attacks it.

[paul.fr]

Excellent information, thank Justin and Chris.

[another_someone]

wow, that's cool chris.  i've never heard of transposons jumping from one cell to another.  i'll have to read up on that.  makes sense though.  gets around the problem of "how does one little cell" create a whole tumor before the body realizes what's going on and attacks it.

OK, so what is the exact difference between a transposon and a virus (is it only that a virus is infectious, from person to person, whereas a transponson is localised to one person - if so, is that a sharp dividing line, or are there shades of grey)?

[MayoFlyFarmer]

viruses and transpossons are completely seperate things, but i think that you hit the most functionally important difference between the two that a transposon is a piece of DNA that can move abotu the genome within ONE SINGLE CELL, while a virus infects from cell to cell (and as you mentioned, from individual to individual).  There is a lot more to a virus than a transposon that allows it to do this that make the two very different.

[DoctorBeaver]

It may be that there is more than 1 gene involved - and not always the same genes. Many functions within the body are the result of multiple genes working together. That is 1 of the things that makes genetics such a complicated issue.

I was studying autism a while back and there are some forms of autism that seem to have a correlation with transposition or deletion. However, the same type of autism can be manifested without the same transpositions or deletions, and those transpositions and deletions can be present without autism being manifested. The same could be true with the genetics of cancers.

[MayoFlyFarmer]

yes, its pretty commonly believed that its very rare for cancer to be caused by a defect in only one gene.  And in the cases where this is though to occur, its usually a case of one gene being initially effected, but then having downstream effects on multiple other genes.

typically to transform a cell (make it go from a normal cell to a cancer-like cell) you have to affect a minimum of three genes.  (similar to transforming a cell into a stem cell as in the study cited by the original poster to this thread.