Lipoxygenase Protein Expression and Its Effect on Oxidative Stress Caused by Benzidine in Normal Human Urothelial Cell Lines

Metabolic activation of indirect-acting carcinogens in the target organ is an effective mechanism of carcinogenesis. Lipoxygenase (LOX) can co-oxidize the bladder carcinogen benzidine (BZ). However, it is not entirely clear whether BZ is activated and which enzyme is involved in its activation in bladder epithelial cells. Our results showed that BZ induced 5-LOX protein expression but had no significant influence on the expression of 15-LOX-2, CYP1B1, and CYP2E1 in SV-40 immortalized human uroepithelial SV-HUC-1 cells. BZ induced oxidative stress in SV-HUC-1 cells by increasing reactive oxygen species (ROS) and malondialdehyde levels significantly in the 100 and 200 μmol/L-BZ-treated groups and decreased the level of the antioxidant reduced glutathione significantly at 200 μmol/L BZ. Concurrently, the activity of catalase was increased, while the activity of superoxide dismutase was increased at 50 μmol/L BZ but gradually decreased with increasing concentrations of BZ ( P < 0.05). However, the oxidative stress and damage in SV-HUC-1 cells caused by BZ were effectively inhibited by the 5-LOX-specific inhibitor AA861 at 10 μmol/L. Thus, 5-LOX is probably the major LOX isozyme to co-oxidize exogenous chemicals in SV-HUC-1 cells. AA861 has a protective effect on the oxidative stress and damage induced by BZ in SV-HUC-1 cells. We conclude that BZ can be activated by 5-LOX to produce ROS and oxidative stress, which may be associated with bladder cancer caused by BZ.

Microelectrical Impedance Spectroscopy for the Differentiation between Normal and Cancerous Human Urothelial Cell Lines: Real-Time Electrical Impedance Measurement at an Optimal Frequency

Purpose. To distinguish between normal (SV-HUC-1) and cancerous (TCCSUP) human urothelial cell lines using microelectrical impedance spectroscopy (μEIS). Materials and Methods. Two types of μEIS devices were designed and used in combination to measure the impedance of SV-HUC-1 and TCCSUP cells flowing through the channels of the devices. The first device (μEIS-OF) was designed to determine the optimal frequency at which the impedance of two cell lines is most distinguishable. The μEIS-OF trapped the flowing cells and measured their impedance at a frequency ranging from 5 kHz to 1 MHz. The second device (μEIS-RT) was designed for real-time impedance measurement of the cells at the optimal frequency. The impedance was measured instantaneously as the cells passed the sensing electrodes of μEIS-RT. Results. The optimal frequency, which maximized the average difference of the amplitude and phase angle between the two cell lines (p<0.001), was determined to be 119 kHz. The real-time impedance of the cell lines was measured at 119 kHz; the two cell lines differed significantly in terms of amplitude and phase angle (p<0.001). Conclusion. The μEIS-RT can discriminate SV-HUC-1 and TCCSUP cells by measuring the impedance at the optimal frequency determined by the μEIS-OF.