Overexpression of hnRNPC2 induces multinucleation by repression of Aurora B in hepatocellular carcinoma cells

摘要

Heterogeneous ribonuclear protein C2 (hnRNPC2), an RNA binding protein, is a component of hnRNPC which is upregulated in many tumors. Multinucleation exists in many tumors and is positively correlated with tumor grade. To uncover the correlation between hnRNPC2 and multinucleation in hepatocellular carcinoma SMMC-7721 cells, we constructed a pEGFP-hnRNPC2 vector and transfected it into cancer cells. Our results revealed that overexpression of hnRNPC2 induced multinucleation in SMMC-7721 cells. Tracking tests indicated that the induced multinucleated cells were unable to recover to mononuclear cells and finally died as a result of defects in cell division. Furthermore, Aurora B, which was localized at the midbody and plays a role in cytokinesis, was repressed in hnRNPC2-overexpressing cells, whose knockdown by RNA interference also induced multinucleation in SMMC-7721 cells. Quantitative polymerase chain reaction (qPCR) and mRNA-protein co-immunoprecipitation results revealed that Aurora B mRNA did not decrease in hnRNPC2-overexpressing cells, instead it bound more hnRNPC2 and less eIF4E, an mRNA cap binding protein and translational initiation factor. Moreover, hnRNPC2 bound more eIF4E in hnRNPC2-overexpressing cells. These results indicate that hnRNPC2 repressed Aurora B binding with eIF4F, which must bind with Aurora B mRNA in order to initiate its translation. This induced multinucleation in hepatocellular carcinoma cells. In addition, hnRNPC2 accelerated hepatocellular carcinoma cell proliferation. Collectively, these data suggest that hnRNPC2 may be a potential target for hepatocellular carcinoma cell diagnosis and treatment.