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The engineered Salmonella typhimurium inhibits tumorigenesis in advanced glioma.

Chen JQ, Zhan YF, Wang W, Jiang SN, Li XY - Onco Targets Ther (2015)

Bottom Line: The differences between the three groups in tumor volume and survival time were analyzed.MRI showed that the tumor volume in the S. typhimurium with ClyA group were significantly reduced compared to the bacteria alone and no bacteria groups 7 days post-doxycycline treatment (P<0.05), while the necrotic tumor volume in the S. typhimurium with ClyA group and S. typhimurium alone group increased significantly compared to the control group (P<0.01).In addition, the survival time was significantly prolonged in the bacteria-treated group compared to the PBS-treated control group (P<0.01).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, People's Republic of China.

ABSTRACT

Objective: To explore the antitumor role of the attenuated Salmonella typhimurium ΔppGpp with inducible cytolysin A (ClyA) in advanced stage of glioma.

Materials and methods: The C6 rat glioma cells were orthotopically implanted by surgery into the caudate nucleus of rat brains. The rats were then randomly divided into the treatment group (SL + ClyA) (n=12), negative control group (SL) (n=12), and control group (phosphate-buffered saline [PBS]) (n=12). In the treatment group, the attenuated S. typhimurium were transformed with the plasmid-encoded antitumor gene ClyA. The expression of ClyA was controlled by the TetR-regulated promoter in response to extracellular doxycycline. The plasmid also contained an imaging gene lux to allow illumination of the tumor infected by the bacteria. The rat glioma C6 cells were implanted into the caudate nucleus of all rats. The engineered S. typhimurium and respective controls were injected intravenously into the rats 21 days after initial tumor implantation. The pathological analysis of the glioma tumor was performed at 21 days and 28 days (7 days after doxycycline treatment) postimplantation. All rats underwent MRI (magnetic resonance imaging) and bioluminescence study at 21 days and 28 days postimplantation to detect tumor volume. The differences between the three groups in tumor volume and survival time were analyzed.

Results: Advanced stage glioma was detected at 21 days postimplantation. Bioluminescence showed that the engineered S. typhimurium accumulated in glioma tumors and disappeared in the normal reticuloendothelial tissues 3 days after intravenous injection. MRI showed that the tumor volume in the S. typhimurium with ClyA group were significantly reduced compared to the bacteria alone and no bacteria groups 7 days post-doxycycline treatment (P<0.05), while the necrotic tumor volume in the S. typhimurium with ClyA group and S. typhimurium alone group increased significantly compared to the control group (P<0.01). In addition, the survival time was significantly prolonged in the bacteria-treated group compared to the PBS-treated control group (P<0.01).

Conclusion: The engineered S. typhimurium can significantly induce cancer cell apoptosis in the tumor center and inhibit cancer cell proliferation in the outer zone of advanced glioma tumor, leading to a prolonged survival time in rats. In addition, the engineered S. typhimurium that carried the antitumor and imaging genes controlled by the TetR-regulated promoter have high delivery efficiency with tolerable side effects in rats.

No MeSH data available.


Related in: MedlinePlus

The distribution of the inducible ClyA gene expression.Notes: (A) Bioluminescence images were obtained following IV injection of the engineered Salmonella typhimurium before doxycycline administration. Expression of luxCDABE in the advanced gliomas was verified by the in vivo bioluminescence imaging at 1, 2, and 3 days after IV injection of the engineered S. typhimurium. (B) Immunoblotting analysis of the expression of ClyA in tumor tissues from rats injected with engineered S. typhimurium before (−) and after doxycycline induction (+). (C) The observed body weights of rats were not significantly different between the three groups at the first 7 days of treatment. P>0.05.Abbreviations: ClyA, cytolysin A; IV, intravenous; Dox, doxycycline; PBS, phosphate-buffered saline; SL, treatment group; d, days.
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f2-ott-8-2555: The distribution of the inducible ClyA gene expression.Notes: (A) Bioluminescence images were obtained following IV injection of the engineered Salmonella typhimurium before doxycycline administration. Expression of luxCDABE in the advanced gliomas was verified by the in vivo bioluminescence imaging at 1, 2, and 3 days after IV injection of the engineered S. typhimurium. (B) Immunoblotting analysis of the expression of ClyA in tumor tissues from rats injected with engineered S. typhimurium before (−) and after doxycycline induction (+). (C) The observed body weights of rats were not significantly different between the three groups at the first 7 days of treatment. P>0.05.Abbreviations: ClyA, cytolysin A; IV, intravenous; Dox, doxycycline; PBS, phosphate-buffered saline; SL, treatment group; d, days.

Mentions: Bioluminescence imaging study showed that the engineered S. typhimurium presented in both tumor and reticuloendothelial tissues on the first day of IV injection of bacteria (Figure 2A). However, the fluorescence signal concentrated in glioma tumor but disappeared in the reticuloendothelial tissues on the third day of IV injection of bacteria (Figure 2A). To confirm that ClyA is inducible upon doxycycline administration, we performed Western blot analysis that successfully detected the presence of ClyA protein in the tumor tissues only after doxycycline administration (Figure 2B). The body weights of rats were not significantly different between the three groups, suggesting that expression of ClyA in tumors by IV administration of engineered S. typhimurium did not elicit severe toxicity (Figure 2C).


The engineered Salmonella typhimurium inhibits tumorigenesis in advanced glioma.

Chen JQ, Zhan YF, Wang W, Jiang SN, Li XY - Onco Targets Ther (2015)

The distribution of the inducible ClyA gene expression.Notes: (A) Bioluminescence images were obtained following IV injection of the engineered Salmonella typhimurium before doxycycline administration. Expression of luxCDABE in the advanced gliomas was verified by the in vivo bioluminescence imaging at 1, 2, and 3 days after IV injection of the engineered S. typhimurium. (B) Immunoblotting analysis of the expression of ClyA in tumor tissues from rats injected with engineered S. typhimurium before (−) and after doxycycline induction (+). (C) The observed body weights of rats were not significantly different between the three groups at the first 7 days of treatment. P>0.05.Abbreviations: ClyA, cytolysin A; IV, intravenous; Dox, doxycycline; PBS, phosphate-buffered saline; SL, treatment group; d, days.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4592054&req=5

f2-ott-8-2555: The distribution of the inducible ClyA gene expression.Notes: (A) Bioluminescence images were obtained following IV injection of the engineered Salmonella typhimurium before doxycycline administration. Expression of luxCDABE in the advanced gliomas was verified by the in vivo bioluminescence imaging at 1, 2, and 3 days after IV injection of the engineered S. typhimurium. (B) Immunoblotting analysis of the expression of ClyA in tumor tissues from rats injected with engineered S. typhimurium before (−) and after doxycycline induction (+). (C) The observed body weights of rats were not significantly different between the three groups at the first 7 days of treatment. P>0.05.Abbreviations: ClyA, cytolysin A; IV, intravenous; Dox, doxycycline; PBS, phosphate-buffered saline; SL, treatment group; d, days.
Mentions: Bioluminescence imaging study showed that the engineered S. typhimurium presented in both tumor and reticuloendothelial tissues on the first day of IV injection of bacteria (Figure 2A). However, the fluorescence signal concentrated in glioma tumor but disappeared in the reticuloendothelial tissues on the third day of IV injection of bacteria (Figure 2A). To confirm that ClyA is inducible upon doxycycline administration, we performed Western blot analysis that successfully detected the presence of ClyA protein in the tumor tissues only after doxycycline administration (Figure 2B). The body weights of rats were not significantly different between the three groups, suggesting that expression of ClyA in tumors by IV administration of engineered S. typhimurium did not elicit severe toxicity (Figure 2C).

Bottom Line: The differences between the three groups in tumor volume and survival time were analyzed.MRI showed that the tumor volume in the S. typhimurium with ClyA group were significantly reduced compared to the bacteria alone and no bacteria groups 7 days post-doxycycline treatment (P<0.05), while the necrotic tumor volume in the S. typhimurium with ClyA group and S. typhimurium alone group increased significantly compared to the control group (P<0.01).In addition, the survival time was significantly prolonged in the bacteria-treated group compared to the PBS-treated control group (P<0.01).

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, People's Republic of China.

ABSTRACT

Objective: To explore the antitumor role of the attenuated Salmonella typhimurium ΔppGpp with inducible cytolysin A (ClyA) in advanced stage of glioma.

Materials and methods: The C6 rat glioma cells were orthotopically implanted by surgery into the caudate nucleus of rat brains. The rats were then randomly divided into the treatment group (SL + ClyA) (n=12), negative control group (SL) (n=12), and control group (phosphate-buffered saline [PBS]) (n=12). In the treatment group, the attenuated S. typhimurium were transformed with the plasmid-encoded antitumor gene ClyA. The expression of ClyA was controlled by the TetR-regulated promoter in response to extracellular doxycycline. The plasmid also contained an imaging gene lux to allow illumination of the tumor infected by the bacteria. The rat glioma C6 cells were implanted into the caudate nucleus of all rats. The engineered S. typhimurium and respective controls were injected intravenously into the rats 21 days after initial tumor implantation. The pathological analysis of the glioma tumor was performed at 21 days and 28 days (7 days after doxycycline treatment) postimplantation. All rats underwent MRI (magnetic resonance imaging) and bioluminescence study at 21 days and 28 days postimplantation to detect tumor volume. The differences between the three groups in tumor volume and survival time were analyzed.

Results: Advanced stage glioma was detected at 21 days postimplantation. Bioluminescence showed that the engineered S. typhimurium accumulated in glioma tumors and disappeared in the normal reticuloendothelial tissues 3 days after intravenous injection. MRI showed that the tumor volume in the S. typhimurium with ClyA group were significantly reduced compared to the bacteria alone and no bacteria groups 7 days post-doxycycline treatment (P<0.05), while the necrotic tumor volume in the S. typhimurium with ClyA group and S. typhimurium alone group increased significantly compared to the control group (P<0.01). In addition, the survival time was significantly prolonged in the bacteria-treated group compared to the PBS-treated control group (P<0.01).

Conclusion: The engineered S. typhimurium can significantly induce cancer cell apoptosis in the tumor center and inhibit cancer cell proliferation in the outer zone of advanced glioma tumor, leading to a prolonged survival time in rats. In addition, the engineered S. typhimurium that carried the antitumor and imaging genes controlled by the TetR-regulated promoter have high delivery efficiency with tolerable side effects in rats.

No MeSH data available.


Related in: MedlinePlus