Non Radioactive Carcinogens

[aj47]

I understand how carcinogens such polonium-210 can cause cancer through radioactive emmision, but what about non radioactive chemicals such as benzene. What properties do these chemicals have that cause them to be carcinogenic and through what mechanisms do they work?

[RyanJ]

I understand how carcinogens such polonium-210 can cause cancer through radioactive emmision, but what about non radioactive chemicals such as benzene. What properties do these chemicals have that cause them to be carcinogenic and through what mechanisms do they work?

 

They are normally highly reactive, are radicals or produce radicals when they break down.

 

These will then find their way into the nucleus and will start to bond with the DNA which cause damage too it - the idea that is believed to cause most cancers.

 

Its simmilar to the idea that radicals may be responsible for some of the effects of ageing

 

Cheers,

 

Ryan Jones

[ecoli]

They are normally highly reactive' date=' are radicals or produce radicals when they break down.

 

These will then find their way into the nucleus and will start to bond with the DNA which cause damage too it - the idea that is believed to cause most cancers.

 

Its simmilar to the idea that radicals may be responsible for some of the effects of ageing

 

Cheers,

 

Ryan Jones[/quote']

 

Ryan J pretty much said it... carcinogenic chemicals, such as ethidium bromide, break the hydrogen bonds that bond the nitrogenous bases. This causes the potential to rearrage or mismatch base pairs causing mutations.

[Bluenoise]

Well that's only half right there are a hell of alot of mechanisms that these chemicals funtion by.

 

The first is by catalyzing the production of reactive spies like radicals. These chemicals are typically photosensitizer for most part. They absorb photons and when they fall back to their normal energy they cause the creation of radicals which can potentially damage dna. The ones strongly implicated in cancer can do this many times, and they need to since the probability of a radical reating with the DNA is really small.

Now there are species that form radicals in other methods, however these tend to form just one radical, and that has a untra low probability to actually reach the DNA to react since it will pretty much react with the first thing it finds.

 

Now the second mechanism is that of Chelating between dna. Chemicals like benzene or PAH (poly aromatic hydrocarbons) have a low solubility in water, so for the body to eliminate them it must add chemical groups to them to make them soluble so they can be secreted in the urine(hydroxyl groups). Unfortunatley these activated aromatic rings look a hell of a lot like nucleic bases and tend to wedge themselves inbetween the rungs in the DNA ladder, causing errors in DNA replication that can lead to cancer.

 

Some chemicals look so much like DNA (Base analogs) that they'll actually be put in place of bases During DNA replication and that can cause cancer as well.

 

Also you can interfere with DNA proof reading and repair mechanism, dna replication has errors associated with it and just that alone can cause cancer.

 

Also hormones can increase cell proliferation that can give potential cancer cells the head start that they need.

 

Oh oxidation of methylated cytosines creates a base that is incorrectly repaired which can cause cancer. (hence the low occurance of methylated cytosines in DNA).

 

Damn even your body heat is enough to cause a spontaneous break in your DNA which if not corrected properly and occuring in a "bad" position can give you cancer.

 

I'm sure there are even more mechanisms.

[ecoli]

Well that's only half right there are a hell of alot of mechanisms that these chemicals funtion by.

 

I was just giving one example... of course there are others.

[Bluenoise]

I was just giving one example... of course there are others.

 

true enough, but sometimes you need to state that.

[aj47]

Great info, much appreciated.