Antiapoptotic Bcl-2 protein's upregulated expression is a key reason for drug resistance leading to failure of chemotherapy. In this report, a series of biocompatible amphiphilic cationic poly[(R)-3-hydroxybutyrate] (PHB)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) copolymer, comprising hydrophobic PHB block and cationic PDMAEMA block, is designed to codeliver hydrophobic chemotherapeutic paclitaxel and Bcl-2 converting gene Nur77/ΔDBD with enhanced stability, due to the micelle formation by hydrophobic PHB segment. This copolymer shows less toxicity but similar gene transfection efficiency to polyethyenimine (25k). More importantly, this codelivery approach by PHB-PDMAEMA leads to increased drug resistant HepG2/Bcl-2 cancer cell death, by increased expression of Nur77 proteins in the Bcl-2 present intracellular mitochondria. This work signifies for the first time that cationic amphiphilic PHB-b-PDMAEMA copolymers can be utilized for the drug and gene codelivery to drug resistant cancer cells with high expression of antiapoptosis Bcl-2 protein and the positive results are encouraging for the further design of codelivery platforms for combating drug resistant cancer cells.

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Nur77 modulators have emerged as a promising therapeutic approach for hepatocellular carcinoma. In this study, a structure-based rational drug design approach was used to design and synthesise a series of 4-((8-hydroxy-2-methylquinolin-4-yl)amino)benzoylhydrazone derivatives based on the binding characteristics of our previously reported 10g and the native ligand 3NB at the binding Site C of Nur77. Cell-based cytotoxicity assays revealed that compound TMHA37 demonstrated the highest cytotoxicity against all tested cancer cells. The induced fit docking and binding pose metadynamics simulation suggested that TMHA37 was the most promising Nur77 binder at Site C. Molecular dynamics simulation validated the stable binding of TMHA37 to Nur77’s Site C but not to Sites A or B. Specifically, TMHA37 bound strongly to Nur77-LBD ( K D = 445.3 nM) and could activate Nur77’s transcriptional activity. Furthermore, TMHA37 exhibited antitumor effects by blocking the cell cycle at G2/M phase and inducing cell apoptosis in a Nur77-dependent manner.

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