engleski

Paraoxonase 1 activity in patients with premalignant lesion of the cervics

Patients with premalignant lesions of cervix show increased lipid peroxidation and changes in antioxidative system, what may suggest presence of oxidative stress in the early phase of carcinogenesis. Paraoxonase 1 (PON1) is a calcium-dependent esterase, synthesized in the liver and secreted into the plasma where is associated with HDL. PON1 hydrolyzes different substrates by its organophosphatase, arylesterase and lactonase activities. Also, PON1 possess antioxidant/antiatherogenic activity, and it removes radicals formed by lipid peroxidation in human body. We carried out this study in order to determine PON1 paraoxonase activity in patients with premalignant lesions of the cervix. Study included fifty-three women [38 (19-38) years] with diagnosis of cervical intraepithelial neoplasia (CIN) that was confirmed by biopsy. 17 patients were classified in CIN1, 17 in CIN2 and 18 in CIN3. Eighty three healthy volunteers [37 (29-43) years], without any cervical or other disease, were enrolled in the study, as a control group. PON1 paraoxonase activity was assayed spectrophotometrically with paraoxon as a substrate in absence and in presence of NaCl. We standardized PON1 basal and salt stimulated paraoxonase activity in relation to the concentration of HDL-cholesterol. Standard lipid parameters, concentration of triglyceride, total cholesterol, HDL cholesterol, LDL cholesterol were determined by commercially available reagents. Serum concentrations of determined lipid parameters were similar between two study groups. However, concentration of HDL cholesterol was significantly reduced in CIN patients [1.5 (1.3-1.6) mmol/L vs 1.8 (1.6-2.1) mmol/L ; P<0.001]. PON1 basal activity [104 (66-226) U/L vs 89 (67-193)U/L ; P=0.344] as well as salt- stimulated paraoxonase activity [210 (131-397) U/L vs 179 (132-346) U/L ; P=0.345] were similar between two study groups. There was no statistically significant difference in PON1 activities standardized to the concentration of HDL cholesterol (basal paraoxonase activity 52 (39-130) U/mmol vs 62 (44-129) U/mmol ; P=0.291 ; salt-stimulated paraoxonase activity 102 (75- 235) U/mmol vs 121 (86-230) U/mmol ; P=0.300). Our results show that PON1 paraoxonase activity is not reduced in patients with CIN. Although these patients have reduced HDL concentration that reduction does not result with changes in PON1 activity. However, it is important to point out the fact that PON1 activity was determined with synthetic substrate (paraoxon) and that activity do not necessarily correlate with antioxidant ability of PON1.

paraoxonase 1 ; cervical intraepitelial neoplasia

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