Induction of apoptosis in cancer cells through N-acetyl-l-leucine-modified polyethylenimine-mediated p53 gene delivery

• N-acetyl-l-leucine-modified polyethylenimines were constructed through EDC/NHS-mediated couple reaction.
• The derivatives exhibited low cytotoxicity, protein adsorption and hemolytic activity, and satisfactory transfection efficiency.
• The derivatives could realize an efficient p53 gene delivery for achieving the proliferative inhibition due to the activation of mitochondria-dependent apoptosis pathway.

Herein, N-acetyl-l-leucine-modified polyethylenimine was successfully constructed through the EDC/NHS-mediated coupling reaction and employed as vectors to accomplish p53 gene delivery using HeLa (p53wt) and PC-3 cells (p53null) as models. Compared with PEI25K, the derivatives exhibited lower cytotoxicity, protein adsorption and hemolytic activity, together with satisfactory pDNA condensation capability and gene transfection efficiency. After p53 transfection, MTT analysis confirmed that the cell proliferation was inhibited. Flow cytometric analysis showed that the derivative-mediated p53 delivery could induce stronger early apoptosis than PEI25K and Lipofectamine2000. Further, PC-3 cells showed higher sensitivity to the exogenous p53 transfection than HeLa cells. The mechanism for inducing apoptosis was determined to be up-regulation of p53 expression at both mRNA and protein levels using RT-PCR and western blotting analysis. Expression level and activity analysis of caspase-3, -8 and -9, and mitochondrial membrane potential measurement revealed that p53 transfection mediated by these derivatives facilitated early apoptosis of tumor cells via a mitochondria-dependent apoptosis pathway. Thus, the derivatives showed potential as biocompatible carriers for realizing effective tumor gene therapy.

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