A comparative study of serum protein-bound sialic acid in benign and malignant prostatic growth: possible role of oxidative stress in sialic acid homeostasis.

Benign and malignant prostatic growths are associated with an increase in sialoconjugates (e.g. prostate-specific antigen (PSA)) in blood. Oxidative stress plays a crucial role in pathogenesis of various malignancies. The objective of this study was to evaluate oxidative stress parameters and protein-bound sialic acid level in sera of prostatic tumor cases and to asses for any association between them. Sera samples were collected and estimated for carbonylation of proteins, lipid peroxidation products, PSA and protein-bound sialic acid from 10 patients in each group with prostatic carcinoma (Ca prostate) and benign prostatic hyperplasia (BPH) along with 10 healthy male subjects of similar age group as control. In carcinoma prostate cases, lipid peroxides, protein carbonyls, protein-bound sialic acid and PSA were significantly increased compared to BPH and controls. There was significant association between oxidative stress parameters (lipid peroxide and protein carbonyl) and sialoconjugates (PSA and protein-bound sialic acid). In BPH cases, serum lipid peroxides and protein-bound sialic acid were significantly higher in comparison to controls and protein carbonyls were correlated with protein-bound sialic acid. ROC curve for sialic acid showed that it can be used as a marker to differentiate carcinoma prostate from benign growth of prostate at a cutoff level of 11.38 mug/mg protein with a sensitivity of 100% and specificity of 80%. We conclude that oxidative stress might be associated with the degree of sialylation of protein and graded changes in these parameters possibly unveil the pathogenic demarcation from benign to malignant condition of prostate.