The Mechanisms Of Apogossypolone Induced Apoptosis And Inversed EMT On Pheochromocytoma Cell Line PC12

Purpose:Malignant pheochromocytoma(PHEO)is exactly diagnosed only at the occurrence of metastatic foci.But at that time,patients are less likely to get many benefits from traditional chemotherapy.The aim of this study is to find and evaluate new effective agents to impede tumor growth and inhibit or delay metastatic formation for the treatment of PHEO.Over-expression of BCL-2 family proteins is tightly correlated with malignant progression of PHEO.ApoG2,targeting BCL-2 family proteins,has exhibited anti-tumor activities in various tumors.In the present study,we sought to investigate the effect of ApoG2 on PHEO in vitro and in vivo.Materials and Methods:In the research,CCK8、Wound healing and Transwell assays were applied to assess the effects of ApoG2 on the proliferation and cell migration/invasion for PC12.Flow cytometry was performed to attest whether ApoG2 affected apoptotic occurrence and cell cycle progression or not.By Immunofluorescence and western blot,we identified expression level and distribution of proteins,trying to probe molecular mechanism.Finally,mouse xenograft model or metastasis model were built to assess the effects in vivo.Results:In the first part of the research,our results indicated that anti-PHEO effect of ApoG2 was through inducing cell apoptosis,but not arresting cell cycle.ApoG2 firstly bound to and then inhibited bcl-2 protein,further releasing proapoptosis protein bax.Dependent on it,ApoG2 subsequently promoted accumulation of ROS on cytoplasm by increasing permeability of mitochondrial membrane.Finally,caspase family proteins,such as caspase 9/7/3 and so on,were cleaved and activated,unavoidably leading to apoptotic occurrence.In the second part of the research,we initially corroborated that ApoG2 could inhibit PC12 cells migration and invasion in vitro.In short,ApoG2 could induce GSK-3/AKT complex formation to down-regulate phosphorylation of PI3K/AKT pathway,subsequently dependent on which ApoG2 conversed Epithelial-mesenchymal transition(EMT)via promoting E-cadherin and β-catenin translocate from cytoplasm to membrane.However,ApoG2 seemed to promote tumor progression,instead of suppress in vivo.Conclusions:Altogether,our results indicated ApoG2 might be an effective target agent early in the disease,not only inhibiting growth of tumors,but also possibly delaying metastasis of tumors.In advanced stage where there are majority of circulating tumor cells,ApoG2 possibly promoted tumors metastasis.Therefore,the patients should be advised to detect circulating tumor cells before treating with anti-EMT drugs.Most importantly,we identified that GSK-3 is not only a downstream effector,but also an upstream regulator of PI3K/AKT pathway.