bigrand said:
Another thing, just becase somthing can act as an antineoplastic agent, doesnt mean its incapable of geing mutanagenic.
Take for example the Cis isomer of Pt(Cl)2(NH3)2, otherwise known as Cis-Platin. This is a widely used chemotherapy drug effective against all kinds of cancers. It targets fast proliferating cells such as cancer cells (and bone marrow, hair ect). It is a square planar molecule that is an intercalating agent meaning it can slide itself into a DNA strand dissrupting it, damaging, mutating it, and killing the cell, or stoping its reproduction as was seen in Cis-platins earlier days (hopefully, mostly cancer cells). Bad thing is, it can mutate non cancerous cells.
Just becasue DNP acts agains cancer cells (through a specific pathway) doesnt mean that it can be carcinogenic (through another pathway).
But, the AMES test is what we have to go on at this point.
Wow... Now this is a guy who has done some reading!
Just a few things to add...
There is a difference between a "mutagen" and a "carcinogen." A "mutagen" is generally thought to pocess intrinsic DNAmutating abillity-- these are detected by the Ames test. On the other hand, a compound can result in cancer but cause no direct or intrinsic mutations in DNA. A good example of this is an analog of diaclylglycerol (I forget the name). It is not readily degraded, at least nearly as fast as DAG, and results in unregulated growth.. Let us not forget that a cell that has lost the ability to control it's growth is the stuff that tumors are made of. In the case of the DAG analog, no DNA mutagenesis occurs, yet the cell becomes cancerous.
Now, cis-platinum, on the other hand, causes cell death but in a different mechanism than pure DNA mutation. This cell death is acutally systematic cell suicide (apoptosis). Cis-platinum induces tumor supressor protein p53, which is the biological kommisar. P53 induction is well characterized in the face of DNA damage caused by uv radiation or chemical agents such as etoposide and cis-platinum. Acutally though, p53 is sometimes induced in the absence of DNA damage, but that is going beyond the scope. The point is: an increase in p53 causes an up-reguation of machinery required for DNA repair, cell cycle arrest, or programed cell death. Does DNP increase p53 levels?
Does DNP cause an increase in reactive oxygen species derived from aerobic metabolism? I used to think so... But now I'm not so sure. An increase in membrane potential or electrochemical gradient in the mito caused inhibition of one of the carriers (cyanide) results in a blockade of electron carrying intermediates. When the half life of one of these intermediates (ubquinone) is increased, it can result in deviant reductions of O2 to superoxide radical--- this fucks shit up.. not just in the mito, but also in the cell (I was wrong before when I said that superoxides formed in the mito stay there).
Now, the interesting thing, and something I carelessly over-looked before is the case during REDUCED membrane potential... This is the scinario DNP causes... A reduced membrane potential may actually result in a reduction in reactive oxygen species.. In vitro? Perhaps. In vivo? Who knows.. I think it's doubtful that a measurable reduction could occur.. But I don't know. If you like, I encorage you to search medline for this...
Bottom line:
Passing the Ames test does not mean a compound cannot cause cancer.... Cadmium is a great example of an agent that has little to no mutagenic power... yet is a carcinogen.
Also- Take your anti-oxidants! NAC has been shown to protect DNA from damage caused by cigarette smoke. Will ALA work in this respect as well? Probably.
Andy