Expression pattern of tumor endothelial marker 8 protein in gallbladder carcinomas

Tumor endothelial marker 8 protein (TEM8) is highly specific to tumor angiogenesis and is not required for normal adult angiogenesis and hence might prove to be a target for anti-angiogenic therapies in the future. We here evaluated protein and gene expression patterns in human endothelial cells of benign gallbladder - gallstone diseases (GSDs) and gallbladder carcinomas (GBCs) using immunostaining, immunofluorescence and western blotting techniques. Subjects comprised 175 GBC patients, 38 males and 137 females, aged 30-85 years (mean age 50.3 ± 13.4 years) and twenty with GSDs, aged 30-75 years, (51.4 ± 10.0 years) for comparison (male 4/20 and females 16/20). TEM8 protein expression increased significantly (p < 0.0001) with increasing stage of GBC and was mostly limited to endothelial cells, although there was no significant change with the grade. Interestingly, only 80-85 kDa and 60 kDa isoforms of TEM8 increased significantly whereas 45 kDa isoform was absent in GBCs. Conclusions- These results suggest that TEM8 plays an unknown important biological role to promote tumor angiogenesis in GBC.