Clinical significance of serum levels of vascular endothelial growth factor and its receptor in biliary disease and carcinoma

AIM: To investigate the clinical significance of serum vascular endothelial growth factor (VEGF) and soluble VEGF receptor-1 (VEGFR1/Flt-1) (sVEGFR1) levels in biliary diseases.METHODS: We analyzed the serum levels of these proteins in patients with acute cholangitis (group 1), biliary malignancies (group 2), and primary biliary cirrhosis or primary sclerosing cholangitis (group 3), and in healthy donors (group 4). The influence of inflammation was also analyzed. Serum VEGF levels were expressed as VEGF per platelet (VEGF/PLT, pg/106) in order to exclude the influence of platelet counts.RESULTS: sVEGFR1 levels were significantly higher in groups 1 and 2 than in the control group, but did not correlate with inflammatory markers. VEGF/PLT levels were generally higher in patients with active inflammation than in those with carcinoma. C-reactive protein strongly correlated with the levels of serum VEGF independently of platelet and leukocyte counts, even in cancer patients. In cancer patients, VEGF/PLT and sVEGFR1 levels might be indicators for evaluating the effect of medical treatment or the disease progression.CONCLUSION: Serum VEGF and VEGFR1 might be useful markers for gauging the clinical effect of various treatments on patients.

Role of Cathepsin G in the Degradation of Glyceraldehyde-3-Phosphate Dehydrogenase Triggered by 4-Hydroxy-2-Nonenal in U937 Cells

Degradation of oxidized or oxidatively modified proteins is an essential part of the cellular antioxidant defense system. 4-Hydroxy-2-nonenal (HNE), a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. HNE-modified proteins are degraded by the ubiquitin-proteasome pathway or the lysosomal pathway. However, our previous studies using U937 cells showed that HNE-modified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is degraded by cathepsin G. In the present study, we examined whether GAPDH in U937 cells treated with HNE in culture is degraded similarly to that incubated with HNE and U937 cell extract. Treatment with HNE for 10 min in culture decreased GAPDH activity in a concentration dependent manner, but did not affect GAPDH degradation. The proteasome activities were not affected by HNE, but culturing with HNE decreased cathepsin G activity and protein level in a concentration dependent manner. These results suggest that HNE-induced oxidative stress leads to decreased cathepsin G activity and results in the loss of GAPDH degradation. Taken together, our findings indicate that cathepsin G has an important role in the degradation of oxidatively modified GAPDH in U937 cells.