Abstract
Transgenic genome integration using non-viral vehicles is a promising approach for gene therapy. Previous studies reported that asparagine is a key regulator of cancer cell amino acid homeostasis, anabolic metabolism and cell proliferation. The depletion of asparagine would inhibit the growth of many cancer cells. In this study, we develop a nanoparticle delivery system to permanently integrate the asparaginase gene into the genome of human lung adenocarcinoma cells. The asparaginase plasmid and the Sleeping Beauty plasmid were co-transfected using amine-functionalized mesoporous nanoparticles into the human lung adenocarcinoma cells. The intracellular asparaginase expression led to the cell cytotoxicity for PC9 and A549 cells. In addition, the combination of the chemotherapy and the asparaginase gene therapy additively enhanced the cell cytotoxicity of PC9 and A549 cells to 69% and 63%, respectively. Finally, we showed that the stable cell clones were successfully made by puromycin selection. The doxycycline-induced expression of asparaginase caused almost complete cell death of PC9 and A549 asparaginase-integrated stable cells. This work demonstrates that silica-based nanoparticles have great potential in gene delivery for therapeutic purposes.
Highlights
Transgenic genome integration using non-viral vehicles is a promising approach for gene therapy
We demonstrated the asparaginase gene delivered by the nanoparticles could effectively kill two human lung adenocarcinoma cells, PC9 and A549, with great additive effect to common chemotherapy drugs
The nanocarrier system can be improved in several ways for in vivo studies in the future: (i) a surface functionalization of Mesoporous silica nanoparticles (MSN) by cancer-targeting ligands can be executed by surface silane coupling reactions
Summary
Transgenic genome integration using non-viral vehicles is a promising approach for gene therapy. We developed the first non-viral gene delivery for asparaginase expression using the SB transposon vectors by polyethyleneimine (PEI)-absorbed MSN to induce lung cancer cell apoptosis (Fig. 1). The doxycycline-treated experiments showed significant lower cell viability, which is only 50% and 60% of the non-treated experiments for PC9 and A549, respectively (Fig. 8b,c) This result supports our hypothesis that the asparaginase induction in the ASNase-carried cells kills themselves and effects the viability of the co-cultured parental cells due to the asparagine depletion in the medium. When performing the transwell experiment in DMEM, we observed no cytotoxicity to the outer chamber cells because DMEM is an asparagine-free medium (Fig. 8b,c) This neighboring effect is very encouraging for the future in vivo work because perfect transfection efficiency may not be required for effective tumor elimination
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