DNA damage and efficacy of DNA repair in patients with type 2 diabetes and coexisting colorectal cancer.
BACKGROUND
Numerous epidemiological studies have indicated that the frequency of developing certain types of cancer, including colorectal cancer (CRC), is higher in patients with type 2 diabetes. The possible causes of this association have not been fully clarified. It has been suggested that chronic hyperglycemia‑related oxidative stress leading to oxidative DNA damage and impaired DNA repair may contribute to increased risk of cancer in type 2 diabetes.


OBJECTIVE
The aim of the study was to evaluate the level of DNA damage and efficacy of DNA repair in patients with CRC with and without type 2 diabetes in comparison with healthy controls.


METHODS
The alkaline comet assay was used to assess the level of endogenous oxidative and H2O2‑induced DNA damage and the efficacy of DNA repair in the lymphocytes of patients with type 2 diabetes, with CRC, with type 2 diabetes and CRC, and of healthy people (a total of 32 patients).


RESULTS
The highest levels of endogenous oxidative and H2O2‑induced DNA damage were found in the lymphocytes of patients with type 2 diabetes and CRC. Additionally, the capacity of DNA repair was significantly decreased in patients with CRC with and without type 2 diabetes.


CONCLUSIONS
Our findings support the hypothesis that an increased risk of cancer in type 2 diabetes may be associated with oxidative DNA damage; however, impaired DNA repair seems to play a major role in carcinogenesis in people with and without type 2 diabetes.
Izabela
I
Szymczak
Agnieszka
A
Sliwińska
Józef
J
Drzewoski
D000975:Antioxidants / Q000494:pharmacology; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000150:complications / Q000378:metabolism*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism*; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects
D000975:Antioxidants; D006861:Hydrogen Peroxide