Increased expression of heat shock protein-binding protein 1 and heat shock protein 70 in human hepatocellular carcinoma tissues

Abstract

Heat shock protein-binding protein 1 (HspBP1) is a co-chaperone that inhibits heat shock 70-kDa protein (Hsp70) activity. In mouse neuroblastomas and lung tumors, the protein levels of HspBP1 and Hsp70 are elevated by a similar amount compared to non-tumor tissues. However, no studies have been reported regarding the levels of HspBP1 in human cancer tissues. Our previous proteomic study demonstrated that the expression of Hsp70 was increased in human hepatitis C virus-related hepatocellular carcinoma (HCV-HCC) tissues. Here, we investigated the expression of HspBP1 in human HCV-HCC. Immunoblotting analysis of HspBP1 and Hsp70 was performed in human HCV-HCC tissues from 20 patients. In 80% of the patients, Hsp70 increased an average of 3.55-fold, and in 50% of the patients, HspBP1 increased an average of 2.02-fold. Comparison and analysis of expression and clinical data revealed a significant difference between moderately-differentiated HCC and non-tumor tissues. In addition, there was a significant difference between the ratio of HspBP1 to Hsp70 levels and tumor size (<3 cm vs. ≥ 3cm) with larger tumors having a lower ratio. This ratio was significantly lower in moderately-differentiated HCC tissues than in non-tumor HCC tissues. In conclusion, HspBP1 was up-regulated in human HCV-HCC, an increase which correlated with the increase of Hsp70 levels. The ratio of HspBP1 to Hsp70 in HCC may provide novel information concerning the characterization of tumors, tumor progression and resistance to treatment.