Arsenic trioxide enhances the chemotherapeutic efficiency of cisplatin in cholangiocarcinoma cells via inhibiting the 14-3-3ε-mediated survival mechanism

Cholangiocarcinoma (CCA) is the second most frequent primary liver carcinoma with high degrees of malignancy and mortality. Chemotherapy plays a key role in the treatment of CCA, however, the low chemotherapeutic efficiency leads to a bottleneck. So unraveling the potential mechanisms to enhance the efficiency (reduced the dosage and enhanced the effects of chemotherapy drugs) and identifying alternative therapeutic strategies in CCA are urgently needed. Here, we found that, in CCA cells, when cisplatin (CDDP) displayed anti-tumor effects, it activated 14-3-3ε simultaneously, which in turn formed a survival mechanism via the phosphorylation of phosphatidylinositol 3-kinase/protein kinase B (PI-3K/Akt). However, low concentrations of arsenic trioxide (ATO) could disrupt such survival mechanism and enhanced the efficiency. For the molecular mechanisms, ATO attenuated 14-3-3ε at both transcriptional and post-transcriptional (ubiquitination degradation) levels. Such repressive effect blocked the activation of PI-3K/Akt, and its downstream anti-apoptotic factors, B-cell lymphoma 2 (Bcl-2), and survivin. Collectively, our present study revealed that the synergistic effects of ATO and CDDP could be a novel approach for enhancing the efficiency, which provides an innovative therapeutic vision for the treatment of CCA.