Polyethylenimine-Modified Bombyx mori Silk Fibroin as a Delivery Carrier of the ING4-IL-24 Coexpression Plasmid.

Longxing Niu,Mingzhong Li,Linling Huang,Guo Chen,Yanfei Feng,Xueping Liu,Ying Guo,Peng Pan

doi:10.3390/polym13203592

Abstract

One of the major challenges for lung cancer gene therapy is to find a gene delivery vector with high efficiency and low toxicity. In this study, low-molecular-weight polyethyleneimine (PEI, 1.8 kDa) was grafted onto the side chains of Bombyx mori silk fibroin (BSF) to prepare cationized BSF (CBSF), which was used to package the plasmid DNA (pDNA) encoded by the inhibitor of growth 4 (ING4) and interleukin-24 (IL-24). FTIR and 1H-NMR spectra demonstrated that PEI was effectively coupled to the side chains of BSF by amino bonds. The results of the trinitrobenzene sulfonic acid method and zeta potential showed that the free amino group content on BSF increased from 125.1 ± 1.2 µmol/mL to 153.5 ± 2.2 µmol/mL, the isoelectric point increased from 3.68 to 8.82, and the zeta potential reversed from − 11.8 ± 0.1 mV to + 12.4 ± 0.3 mV after PEI grafting. Positively charged CBSF could package pDNA to form spherical CBSF/pDNA complexes. In vitro, human lung adenocarcinoma A549 cells and human embryonic lung fibroblast WI-38 cells were transfected with CBSF/pDNA complexes. Confocal laser scanning microscopy analysis and flow cytometry tests showed that CBSF/pDNA complexes can effectively transfect A549 cells, and the transfection efficiency was higher than that of 25 kDa PEI/pDNA complexes. CCK-8 assay results showed that CBSF/pDNA complexes significantly inhibited the proliferation of A549 cells but had no significant effect on WI-38 cells and exhibited lower cytotoxicity to WI-38 cells than 25 kDa PEI. Therefore, a gene delivery system, constructed with the low-molecular-weight PEI-modified silk fibroin protein and the ING4-IL-24 double gene coexpression plasmid has potential applications in gene therapy for lung cancer.

Highlights

Lung cancer has become a leading cause of cancer-related deaths worldwide due to its high incidence, strong aggressiveness, late diagnosis, and lack of effective treatments [1]
The obtained cationized BSF (CBSF) could encapsulate double gene coexpression plasmid DNA encoded by inhibitor of growth 4 (ING4) and IL-24 to form CBSF/pDNA complexes
The complexes were transfected into human lung adenocarcinoma cells A549 and human embryonic lung fibroblasts WI-38 in vitro

Summary

Introduction

Lung cancer has become a leading cause of cancer-related deaths worldwide due to its high incidence, strong aggressiveness, late diagnosis, and lack of effective treatments [1]. ING4 can inhibit the transcriptional activity of nuclear factor NF-κB and hypoxia-inducible factor HIF-1α to inhibit tumor angiogenesis, which has been revealed to have a suppressive role in various cancers, such as lung cancer, hepatocellular carcinoma, glioma, breast cancer, colon cancer, and ovarian carcinoma [5,6]. Interleukin-24 (IL-24) is a membrane receptor-mediated tumor growth inhibitory factor that inhibits the expression of the transcription factor GLI1 in lung cancer cells by inhibiting the Akt-mTOR and SDF-1/CXCR4 signaling axes, thereby inducing DNA damage in lung cancer cells and leading to cell death [7]. Tumor cells often contain multiple genetic abnormalities, which limit the efficacy of a single gene-mediated cancer therapy [9]. The coexpression of the ING4 and IL-24 double genes can selectively inhibit tumor angiogenesis and the growth of tumor cells through pathways both inside and outside of the cells

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Conclusion