Abstract
Liver polyploidization can be induced not only during normal liver development but also under pathological conditions. Polyploidy is a driving force of aneuploidy and thereby may play an important role in carcinogenesis. In the present study, we aim to investigate whether hepatitis B virus may promote hepatocarcinogenesis through the induction of hepatocyte polyploidy. To monitor the impact of HBV on mitotic cell division, we established stable cell lines carrying HBV large surface proteins (LHBs) on human telomerase reverse transcriptase (hTERT)-immortalized hepatocytes. With the application of time-lapse live cell imaging, two major mitotic defects elicited by LHBs proteins were identified: cytokinesis failure and multipolar division. Our results indicate that cytokinesis failure is the major cause of hepatocyte polyploidy and that subsequent multipolar division could directly prompt cell aneuploidy. In addition, we checked the status of chromosome stability by chromosome spreading and fluorescence in situ hybridization (FISH), and demonstrated that the majority of LHBs-expressing cells contained aneuploid genome contents. We also found that LHBs prolonged mitotic progression and promoted overall cell proliferation. To further explore the underlying mechanism leading to cytokinesis failure, we closely examined the progress of cytokinesis in these cells and found that most cells failed to execute the last stage of membrane abscission even after the formation of midbody. Notably, lagging chromosomes and chromosome bridges were frequently identified in those cells underwent cytokinesis failure, suggesting a potential role of chromosome segregation errors in these cells. Taken together, our study provides the first and direct evidence for the role of HBV LHBs protein on chromosome instability through the induction of cytokinesis failure and multipolar division.