N-Isopropylacrylamide-modified polyethylenimine-mediated p53 gene delivery to prevent the proliferation of cancer cells.

In this paper, N-isopropylacrylamide-modified polyethylenimine (PEN) was constructed through Michael addition and employed as a carrier to achieve the p53 gene delivery, using HeLa (p53wt) and PC-3 cells (p53null) as models. After PEN-mediated p53 transfection, expression level of p53 in HeLa and PC3 cells was up-regulated at both mRNA and protein levels. Due to the exogenous p53 expression, the inhibition of cell proliferation was observed through MTT analysis, attributing to the activation of apoptosis and cell cycle arrest. Using flow cytometric analysis, early apoptotic ratios of 54.95% and 27.06% after PEN-mediated p53 transfection were detected in PC-3 and HeLa cells, respectively, indicating that PC-3 cells were more sensitive to the exogenous p53 transfection than HeLa cells. Meanwhile, G1 phase arrest was detected in PC-3 cells while a unique G2 phase arrest was identified in HeLa cells after p53 transfection. Through Western blotting, activity analysis of caspase-3, caspase-8 and caspase-9 and mitochondrial membrane potential measurement, the apoptosis induced by PEN-mediated p53 transfection was conducted in a mitochondria-dependent apoptosis pathway. These results demonstrated that PEN could successfully mediate the p53 gene delivery and up-regulate the cellular p53 expression level, triggering a significant p53-dependent anti-proliferative effect on tumor cells.