Background: Effective therapeutic combinations targeting the oncogenic pathway still are unknown in human hepatocellular carcinoma (HCC). The authors previously identified aberrant expression of aurora B kinase as the independent predictor for the lethal recurrence of HCC, showing that AZD1152 induced in vitro and in vivo apoptosis with polyploidy in human HCC cells. In this preclinical study, the combined effects of molecular-targeted therapies were evaluated based on the cellular response of aurora B inhibition.
Methods: This study analyzed the expression of Bcl-2 family proteins in polyploidization induced by AZD1152 and the in vitro synergistic effects of AZD1152 with control of the Bcl-2 family pathway in human HCC cells. The in vivo effects of the combination therapy targeting the specific molecules were evaluated using subcutaneous tumor xenograft models.
Results: The findings showed that Bcl-xL was specifically overexpressed in AZD1152-induced polyploid HCC cells. The combination of AZD1152 followed by Bcl-xL/2 inhibitor ABT263 induced synergistically cellular apoptosis (p < 0.001) and growth inhibition (p < 0.0001). Interestingly, the reverse sequential administration of AZD1152 combined with pretreatment of ABT263 was less effective than the original one. In vivo studies using tumor xenografts of human HCC cells showed that combination therapy of ABT263 after AZD1152 pretreatment induced significant intratumoral apoptosis (p < 0.05) and remarkable anti-tumor effects (p < 0.05) without a severe adverse effect compared with the monotherapy.
Conclusion: Based on Bcl-xL overexpression in polyploidy induced by aurora B inhibition, the rationale for therapeutic combinations targeting aurora B and Bcl-xL was demonstrated in the authors' preclinical studies, leading to a promising novel approach for the mechanism-based treatment of human HCC.