Evidence for upregulated repair of oxidatively induced DNA damage in human colorectal cancer

Published

September 15, 2011

Author(s)

M Miral Dizdar, Pawel Jaruga, Prasad T. Reddy, Guldal Kirkali, Didem Keles, Gulgun Oktay, Aras E. Canda

Abstract

Molecular pathways that play a role in the development of colorectal cancer involve multiple genetic changes in cancer-related genes that may be caused by overproduction of oxygen-derived species including free radicals, which are capable of damaging DNA and other biomolecules in vivo. Increased DNA damage contributes to genetic instability and promote the development of malignancy. We hypothesized that the repair of oxidatively induced DNA base damage may be modulated in colorectal malignant tumors, resulting in lower levels of DNA base lesions than in surrounding pathologically normal tissues. To test this hypothesis, we investigated oxidatively induced DNA damage in cancerous tissues and their surrounding normal tissues of patients with colorectal cancer. The levels of oxidatively induced DNA lesions such as 4,6-diamino-5-formamidopyrimidine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 8-hydroxyguanine and (5'S)-8,5'-cyclo-2’-deoxyadenosine were measured by gas chromatography/isotope-dilution mass spectrometry and liquid chromatography/isotope-dilution tandem mass spectrometry. We found that the levels of these DNA lesions were significantly lower in cancerous colorectal tissues than those in surrounding non-cancerous tissues. In addition, the level of DNA lesions varied between colon and rectum tissues, being lower in the former than in the latter. The results strongly suggest upregulation of DNA repair in malignant colorectal tumors that may contribute to the resistance to therapeutic agents affecting the disease outcome and patient survival. The type of DNA base lesions identified in this work suggests the upregulation of both base excision and nucleotide excision pathways. Development of DNA repair inhibitors targeting both repair pathways may be considered for selective killing of malignant tumors in colorectal cancer.

Citation

Dna Repair

Issue

10

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.dnarep.2011.08.008

Keywords

DNA damage, DNA repair, GC/MS, Halobacterium salinarum, ionizing radiation, radioresistance thaliana, Candida albicans

Citation

, M. , Jaruga, P. , Reddy, P. , Kirkali, G. , Keles, D. , Oktay, G. and Canda, A. (2011), Evidence for upregulated repair of oxidatively induced DNA damage in human colorectal cancer, Dna Repair, [online], https://doi.org/10.1016/j.dnarep.2011.08.008 (Accessed October 14, 2024)