Intratumoral enrichment of gene delivered by oral administration of recombinant attenuated Salmonella typhimurium in tumor-bearing nude mice / 第二军医大学学报

ABSTRACT

Objective To observe the distribution and expression of exogenous gene delivered by oral administration of recombinant attenuated Salmonella typhimurium in nude mouse model carrying human saliva gland adenoid cystic carcinoma. Methods The attenuated Salmonella typhimurium of green fluorescent protein (GFP) gene expression was constructed by transfecting prokaryotic and eukaryotic expression plasmid vector into the attenuated Salmonella typhimurium SL7207, and the recombinant attenuated Salmonella typhimurium SL7207-pUC-GFP for prokaryotic expression and SL7207-pEGFP-Nl for eukaryotic expression were obtained. The expression stability of GFP gene in the prokaryotic SL7207-pUC-GFP was tested for 10 times in vitro. The nude mouse models carrying human saliva gland adenoid cystic carcinoma were orally administered with prokaryotic SL7207-pUC-GFP (0. 1 mL,l×109 cfu/mL), and then the distribution of the attenuated Salmonella typhimurium in the liver, spleen and tumor tissues were assessed by observing GFP expression in SL7207-pUC-GFP clones cultured out of the tissues homogenate at 24 h, 48 h, 5 d, 10 d, 20 d, and 30 d after oral administration. The nude mouse models were also orally administered with eukaryotic SL7207-pEGFP-Nl, and the expression of GFP in the liver, spleen and tumor tissues was observed in frozen tissue sections 5 d later under fluorescence microscope. Results The expression of GFP harbored by the recombinant attenuated Salmonella typhimurium SL7207-pUC-GFP was not reduced or lost after 10 times of in vitro passaging. After the oral administration of prokaryotic SL7207-pUC-GFP, the attenuated Salmonella typhimurium could survive in the liver, spleen and tumor tissues for a long time, with the clone numbers in tumor tissues being significantly higher than those in the liver and spleen tissues at all the time points (P<0. 05). After oral administration of eukaryotic SL7207-pEGFP-Nl, the expression of GFP was higher in tumor tissues than in the liver and spleen tissues. Conclusion The recombinant attenuated Salmonella typhimurium can be enriched in human saliva gland adenoid cystic carcinoma cells and deliver the harbored exogenous gene into the tumor cells for expression, showing a double advantage for gene therapy.