HBx Integration in Diffuse Large B-cell Lymphoma Inhibits Caspase-3-PARP Related Apoptosis

Abstract

Abstract Purpose: Diffuse large B-cell lymphoma (DLBCL) is the most common pathological type of non-Hodgkin lymphoma (NHL) and is closely associated with hepatitis B virus (HBV) infection and hepatitis B X (HBx) gene integration. This project investigates the cellular biological effects and molecular mechanisms responsible for lymphomagenesis and the progression of HBx gene integration in DLBCL. Methods: The integration of the HBx gene was monitored using sequencing technology, and variations in cell biological effects and related molecular mechanisms were investigated using exvivocell experiments, which were verified in experimental animals and clinical cases. Results: The data shows that clinical DLBCL cells demonstrate HBx integration, and the sequencing analysis validated enabled successfully constructed HBx transfected cells. Compared with control cells, HBx transfected cells had a significantly reduced proportion of mitochondrial membrane potential, obviously reduced signals of chromosome DNA breaks, and proportion of apoptotic cells. Therefore, HBx integration was able to cause the biological outcome of apoptosis reduction. Further studies found that this decreased apoptosis level is associated with a significantly reduced downstream of cleaved Caspase-3 and poly ADP-ribose polymerase (PARP) proteins, revealing the molecular mechanisms of HBx-associated apoptosis in DLBCL. The animal experiments also demonstrated that the protein expression of cleaved Caspase-3 and PARP was prominently reduced in HBx transfected cells from a subcutaneous tumor in nude mice. Overall, the clinically observed expression of cleaved PARP proteins in tissues of HBx-positive DLBCL patients is lower than in HBx-negative patients. Conclusion: In DLBCL, HBx gene integration inhibits cell apoptosis through the Caspase-3-PARP pathway.