Low molecular weight proteins and enzymes in the urine of patients with bladder cancer - a pilot study

A steady increase in cases of bladder cancer (BC) has been observed. Detection of unfavorable changes, especially in the early stages of disease, is crucial to medical procedure. There is still a need to search for new, non-invasive biomarkers of BC. The aim of this study was to estimate the levels of selected low molecular weight proteins (LMWP) and enzymes in the urine of patients at different BC stages and grades.

Urine samples from 46 patients with BC and 16 healthy controls were examined. We measured levels of LMWP such as: retinol-binding protein (RBP), β2 -microglobulin (β2M), enzymes: N-acetyl-β-D-glucosaminidase (NAG), isoform (NAG-B) and also neutrophil gelatinase-associated lipocalin (NGAL).

The levels of all examined parameters differed between patients and healthy subjects. Levels of NAG (p = 0.031), NAG-B (p = 0.023) and NGAL (p = 0.008), and total protein (p = 0.007) concentrations, were significantly higher in the BC patients than in the control group. Among the examined parameters, positive significant correlations were observed only between urinary NGAL concentration and tumor stages and grades. The highest percentages of changes in NGAL concentration were observed in tumor in situ (TIS) and G3grade patients.

Our study showed that urinary NGAL concentrations, as well as NAG and NAG-B activity, could be helpful noninvasive parameters for the diagnosis of BC. The most promising seems to be NGAL determination, but further study is needed on a larger group of participants in order to confirm this observation.