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Updated: Jun 17, 2025
Measuring Growth and Gene Expression Dynamics of Tumor-Targeted S. Typhimurium Bacteria
Published on: July 6, 2013
S100a8/a9 regulated by LPS/TLR4 axis plays an important role in Salmonella-based tumor therapy and host defense
Yanxia Guo1, Yujie Sun1, Zhongying Li1
1The Affiliated Xiangtan Central Hospital of Hunan University, School of Biomedical Sciences, Hunan University, Changsha, China.
Abstract:
Bacteria are ideal anticancer agents and carriers due to their unique capabilities that are convenient in genetic manipulation, tumor-specific targeting, and deep-tissue penetration. However, the specific molecular mechanisms of bacteria-mediated cancer therapy (BMCT) have not been clarified. In this study, we found that TLR4 signaling pathway is critical for Salmonella-mediated tumor targeting, tumor suppression, and liver and spleen protection. TLR4 knockout in mice decreased the levels of cytokines and chemokines, such as S100a8, S100a9, TNF-α, and IL-1β, in tumor microenvironments (TMEs) after Salmonella treatment, which inhibited tumor cell death and nutrient release, led to reduced bacterial contents in tumors and attenuated antitumor efficacy in a negative feedback manner. Importantly, we found that S100a8 and S100a9 played a leading role in Salmonella-mediated cancer therapy (SMCT). The antitumor efficacy was abrogated and liver damage was prominent when blocked with a specific inhibitor. These findings elucidated the mechanism of Salmonella-mediated tumor targeting, suppression, and host antibacterial defense, providing insights into clinical cancer therapeutics.
Insights
Salmonella bacteria target tumors effectively, utilizing the TLR4 pathway. This mechanism involves S100a8 and S100a9, crucial for cancer therapy efficacy and host protection.
Area of Science:
- Microbiology
- Immunology
- Oncology
Background:
- Bacteria offer unique advantages for cancer therapy, including genetic manipulability, tumor targeting, and deep-tissue penetration.
- The precise molecular mechanisms underlying bacteria-mediated cancer therapy (BMCT) remain incompletely understood.
Purpose of the Study:
- To elucidate the molecular mechanisms of Salmonella-mediated cancer therapy (SMCT).
- To investigate the role of the TLR4 signaling pathway in Salmonella's anti-tumor effects and host defense.
Main Methods:
- Utilized TLR4 knockout mice to assess the impact on Salmonella treatment.
- Analyzed cytokine and chemokine levels (S100a8, S100a9, TNF-α, IL-1β) in tumor microenvironments (TMEs).
- Investigated the effect of blocking S100a8 and S100a9 on therapeutic efficacy and liver damage.
Main Results:
- TLR4 signaling is critical for Salmonella-mediated tumor targeting, suppression, and protection of liver and spleen.
- TLR4 knockout mice showed reduced anti-tumor efficacy due to decreased cytokine/chemokine levels, inhibited tumor cell death, and reduced bacterial load.
- S100a8 and S100a9 were identified as key mediators of SMCT, with their blockade abrogating anti-tumor effects and causing liver damage.
Conclusions:
- The study clarifies the mechanism of Salmonella-mediated tumor targeting, suppression, and host defense via the TLR4 pathway.
- S100a8 and S100a9 play a pivotal role in the efficacy of SMCT.
- These findings provide crucial insights for advancing clinical cancer therapeutics using bacteria.
