[8-oxoguanosine as a marker of neoplastic process in brain]

Reactive oxygen species are toxic and cancerogenic factors to living organisms. They are suggested to cause DNA damage (modification) that triggers cancer development. It seems that oxidative damage product 8-oxo-deoxyguanosine (8-oxo-dG) which induces transversion of G to T could be a good chemical marker for cancerogenesis. The aim of our studies was to use 8-oxo-dG as a probe for brain tumour in 17 patients operated on for intracranial neoplasm. Among the patients there were 7 female and 11 male aged from 14 to 60 year. Mean age was 42.88 +/- 16.14 yrs. Several types of tumours were selected histopathologically: from neuroepithelial tissue--6 cases, meningeomas--4, metastases--3, lymphomas--2, neurinoma--1 and chondrosarcoma--1. The tumour tissue was collected from removed material and stored at -20 degrees C. DNA from the neoplastic tissues was isolated by salt method. After hydrolysis of DNA with nuclease P1 and dephosphorylation with bacterial alkaline phosphatase, the mixture of nucleosides was analysed by liquid chromatography method connected with electrochemical detector (HPLC-ECD) working at potential 400 mV. We found higher level of 8-oxo-dG in DNA of patients with malignant tumour (glioblastoma). However, at the present stage of these studies there was no proportional correlation between the level of 8-oxo-dG in DNA in tumour tissue and its malignancy.