Increased expression of peripheral benzodiazepine receptors and diazepam binding inhibitor in human tumors sited in the liver

The peripheral benzodiazepine receptor system triggers intracellular metabo lic events and has been associated with cell proliferation. Its endogenous ligand, the diazepam binding inhibitor, contributes to steroidogenesis by p romoting cholesterol delivery to the inner mitochondrial membrane. The pres ent study was undertaken to verify whether this system is altered in tumors sited in the liver. Peripheral benzodiazepine receptors and diazepam bindi ng inhibitor were studied using immunocytochemistry and in situ hybridizati on in 9 human tumors sited in the liver, in liver hyperplasia, cirrhotic no dular regeneration, intestinal adenocarcinoma and in surrounding non-tumora l tissue. Immunocytochemical staining and in situ hybridization demonstrate d that peripheral benzodiazepine receptors and diazepam binding inhibitor w ere more prominently expressed in neoplastic cells than in non-tumoral tiss ue. They were present in the same cells, suggesting that diazepam binding i nhibitor may act in an intracrine manner in these cells. Higher peripheral benzodiazepine receptors and diazepam binding inhibitor expression in tumor cells suggest an implication of this system in the metabolism of neoplasti c cells. Furthermore the evaluation of peripheral benzodiazepine receptor a nd diazepam binding inhibitor expression might be useful in evaluating mali gnancy and in diagnostic approaches of tumors in liver tissue.