High-throughput screening for Salmonella avirulent mutants that retain targeting of solid tumors

ABSTRACT: Salmonella has a natural ability to target a wide range of tumors in animal models. However, strains used for cancer therapy have generally been selected only for their avirulence rather than tumor-targeting ability. To select Salmonella strains that are avirulent and yet efficient in tumor-targeting, a necessary criteria for clinical applications, we measured the relative fitness of 41,000 Salmonella Typhimurium transposon insertion mutants growing in mouse models of human prostate cancer and melanoma. Two classes of potentially safe mutants were identified. Class 1 mutants showed reduced fitness in normal tissues and unchanged fitness in tumors (e.g., mutants in htrA, SPI-2, and STM3120). Class 2 mutants showed reduced fitness in tumors and normal tissues (e.g., mutants in aroA and aroD). Class 1 mutants are more suitable for delivery of therapeutics for cancer therapy. A library of 41,000 Salmonella mutants containing mini-Tn5 transposon insertions was constructed and pooled. The pool was injected into six human prostate (PC3) and six melanoma (MDA-MB-435) tumors growing subcutaneously in nude mice, and injected intravenously into three tumor-free mice. Bacteria were recovered after two days from tumors and spleens, livers, and lungs of tumor-free mice. During in vivo selection, defective mutants in genes contributing to fitness in the selective environment are lost from the pool. Differences in the mutant pool composition before (input pool) and after selection (output pool) can be detected using microarray hybridization: Transposons were used that carry the T7 promoter sequence, allowing the specific amplification of genomic sequences adjacent to each insertion, which are then mapped on the Salmonella genome using a gene microarray

ORGANISM(S): Salmonella enterica subsp. enterica serovar Typhimurium str. 14028S

SUBMITTER: Ming Zhao 

PROVIDER: E-GEOD-19609 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress