Causes of Oncogenic Mutations

Mutations that trigger and promote tumor formation may be caused by a number of processes. Briefly summarized, the following factors are involved  

There are many endogenous processes that change the information content of the DNA. These processes are inseparable from the performance and characteristics of an organism and they are only influenced by external factors to a small extent. 

Replication of DNA does not occur with complete precision, but rather has an intrinsic inaccuracy. The error rate for incorporation of nucleotides in DNA replication is of the order of one error per 10 - 10 correctly incorporated nucleotides. 

DNA has only a limited stability in the temperature and pH conditions of an organism. Spontaneous changes in the DNA structure may occur and cleavage of purine bases is assigned an important role. The apurinic sites resulting from depurination may give rise to mutations if not repaired. 

Reactive metabolic products are an important cause of endogenous damage to DNA. In first place is reactive oxygen, which can lead to DNA damage, especially in the form of the superoxide anion 02 and in the form of OH radicals. Dietary components also include many chemical compormds with which DNA can react. Furthermore, dietary components can be converted by metabohc activitation into compounds with a high potential for damage of DNA. 

---