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Salmonella typhimurium specifically chemotax and proliferate in heterogeneous tumor tissue in vitro
Author(s) -
Kasinskas Rachel W.,
Forbes Neil S.
Publication year - 2006
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20883
Subject(s) - chemotaxis , in vivo , in vitro , bacterial growth , biology , salmonella , secretion , bacteria , microbiology and biotechnology , fluorescence microscope , tumor microenvironment , cancer cell , chemistry , cancer , tumor cells , fluorescence , biochemistry , cancer research , receptor , genetics , physics , quantum mechanics
Abstract Multi‐drug resistance greatly limits the efficacy of conventional blood‐born chemotherapeutics, which have limited ability to penetrate tumor tissue and are ineffective at killing quiescent cells far from tumor vasculature. Nonpathogenic, motile bacteria can overcome both of theses limitations. We hypothesize that the accumulation of S. typhimurium in tumors is controlled by two mechanisms: (1) chemotaxis towards compounds produced by quiescent cancer cells and (2) preferential growth within tumor tissue. We tested this hypothesis by quantifying the relative contributions of these mechanisms using the tumor cylindroid model, which mimics the microenvironments of in vivo tumors. Time‐lapse fluorescence microscopy was used to measure the accumulation of GFP‐labeled S. typhimurium into cylindroids of different size. Cylindroids larger than 500 µm in diameter contain quiescent cells, whereas cylindroids smaller than 500 µm do not. Spatio‐temporal profiles of bacterial concentration were fit to a mathematical model to calculate two parameters that describe bacterial interaction with tumors: intratumoral bacterial growth, M , and intratumoral bacterial chemoattraction, K . It was observed that S. typhimurium is attracted to cylindroids and accumulate at long time points in the central region of large cylindroids. Both intratumoral bacterial growth and chemotaxis were significantly greater in large cylindroids, suggesting that quiescent cells secrete bacterial chemoattractants and the presence of necrotic and quiescent cells enable S. typhimurium to replicate in tumor tissue. In this study, several mechanisms of S. typhimurium accumulation in solid tumors have been quantified, which we believe is an important step in the development of bacterial‐based therapeutics to target tumor quiescence. © 2006 Wiley Periodicals, Inc.