Serum and whole blood Zn, Cu and Mn profiles and their relation to redox status in lung cancer patients

Abstract

Disturbed redox status may be critical to lung cancerogenesis, however little research has been conducted on general changes in total redox status in lung cancer. Levels and activities of antioxidants, especially enzymatic ones, are related to trace element concentration. Trace element status is often disturbed in cancers, however no studies concerning the association between redox and trace element status have been performed for lung cancer. We hypothesized that disturbed redox status in lung cancer patients is partially determined by trace elements while their distribution amongst blood compartments may differ compared to healthy subjects. Blood samples from lung cancer patients (n=44) and control subjects (n=44) were collected to assess redox and trace element status. Serum and whole blood Cu and Mn levels were determined with GF-AAS, and Zn-with F-AAS. In serum the total antioxidant status (TAS) was determined with the commercial kit TAS (Randox, UK), total oxidant status (TOS) was determined based on the method developed by Erel and the oxidative stress index (OSI) was calculated. Total protein (T-Prot), albumin (Alb), uric acid (UA) and total bilirubin (T-Bil) concentrations were measured with an auto-analyser (Konelab 20i, Thermoscientific, USA), SOD and CAT activity - with commercially available kits (Cayman, USA). The level of TAS, T-Prot, Alb, T-Bil, the activity of SOD, the concentration of whole blood Mn as well as serum and whole blood Zn were lower while TOS, OSI, serum Cu levels and serum Cu:Zn ratios were higher in lung cancer patients compared to the control group. In the lung cancer group TAS correlated positively with Alb and UA, serum Zn and negatively with whole blood Mn. Additionally, SOD positively correlated with the whole blood Mn and Cu:Zn ratio, while CAT - negatively with the whole blood Cu:Zn ratio. In the lung cancer sub-group at clinical stage I-II, TOS additionally negatively correlated with whole blood Zn, and CAT negatively with serum Cu and Cu:Zn ratio. In advanced lung cancer, we found a positive correlation between TAS and serum Zn, and a negative one - with serum Cu:Zn ratio. We observed a similar correlation between endogenous non-enzymatic antioxidants and TAS in the control group, however considerably fewer correlations between trace elements and antioxidants were observed. This study supports the hypothesis that disturbed redox status in lung cancer patients is linked with alterations in trace element status regarding Zn, Mn and Cu. Moreover, the type of biological fluid influences both - alterations in the metal profile and relationships with redox status parameters.

Keywords: Albumin; Antioxidant enzymes; Oxidative stress; Total antioxidant status; Trace elements; Uric acid.