Background: Cancer is a major cause of death throughout the world. Xanthine oxidase (XO) is considered an oxygen derived free radicals producer and paraoxonasel (PON1) is known as a free radicals scavenger. This study was undertaken to determine the activity of PON1 and XO and their concentration along with the lipid profile, lipid peroxide, and thiol level in cancer patients and healthy persons.
Methods: Antigen competitive ELISA was used to determine the level of paraoxonasel and xanthine oxidase in plasma. Paraoxonase and arylesterase activity of the PON1 enzyme and the activity of the XO enzyme were also determined. PON1 and XO activity, cholesterol, LDL-C, HDL-C, lipid peroxides, and thiol level in patients with breast cancer (n = 50), prostate cancer (n = 20), lung cancer (n = 12,), cervix cancer (n = 15), Non-Hodgkin lymphoma (n = 10), and acute lymphoblastic lymphoma (n = 8) and total age matched healthy persons (n = 115) were studied.
Results: Low plasma paraoxonase/arylesterase activities (p < 0.05) and the concentration of the PON1 enzyme were observed in all cancer patients. An elevated level of XO activity was observed in cancer patients. Among different cancers, comparatively high level of XO activity was noted in acute lymphoblastic lymphoma patients (0.18 +/- 0.03, p = 0.001) except cervix cancer patients (0.053 +/- 0.03, p = 0.0029) where a low level was observed. Low HDL-C (p < 0.01), cholesterol (p < 0.01), triglycerides (p < 0.01), thiol levels (p < 0.01) and high lipid peroxide levels (p > 0.05) were observed in cancer patients.
Conclusions: Lower PON1 and high XO enzyme activities cause an imbalance of the free radical system which enhances the lipid peroxidation and other pathological conditions. Lower HDL-C level is also indicative of the low level of PON1 enzyme activity.