Human Gyrovirus-Apoptin Interferes with the Cell Cycle and Induces G2/M Arrest Prior to Apoptosis

The human gyrovirus-Apoptin (HGyv-Apoptin) is a protein that gained attention because it is selectively cytotoxic toward cancer cells. In this study, we have investigated the effect of HGyv-Apoptin on cell cycle progression of cancer cells. We also compared HGyv-Apoptin's action to its homologue chicken anemia virus Apoptin (CAV-Apoptin). We show that HGyv-Apoptin induces G2/M arrest in cancer cells. This is at least in part due to the fact that HGyv-Apoptin induces an abnormal spindle formation in mitotic cells that do not progress properly throughout the cell cycle. HGyv-Apoptin most likely inhibits APC function leading to a sustained cyclin-B1-expression. These results indicate that HGyv-Apoptin has a similar mechanism of action as its homolog CAV-Apoptin and further supports its cancer therapeutic potential.