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Toll-like receptor signaling in anti-cancer immunity
Masato Okamoto1, Mitsunobu Sato
1Second Department of Oral and Maxillofacial Surgery, Tokushima University School of Dentistry, Tokushima, Japan.
Abstract:
It is important to augment the anti-cancer host response in cancer treatment. Recent studies suggested that the signaling via Toll-like receptors (TLRs) which are newly identified receptor molecules recognizing many pathogens, are involved in the induction of anti-cancer immunity. Seya et al. demonstrated that maturation of dendritic cells (DCs) and cytokine induction by the cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guerin (BCG-CWS) are induced via both TLR2 and TLR4. Akira et al. discovered a new molecule of TLR family, TLR9, recognizing unmethylated bacterial CpG-DNA, whose clinical use is expected for cancer therapy as a potent inducer of a helper T cell 1 (Th1)-type T-cell response. TLR9-deficient mice did not show any responses to CpG-DNA, including Th 1 cytokine production and maturation of DCs. We have obtained two molecules, a lipoteichoic acid-related molecule isolated from streptococcal agent OK-432, and a plant-derived 55-kDa protein that can induce Th1 response and elicit a strong anti-cancer effect in vivo and in vitro. Our basic experiments demonstrate that TLR4 signaling is intimately involved in anti-cancer immunity induced by these immunopotentiators. Our clinical examination in oral cancer patients also suggests the requirement of both TLR4 and MD-2 in the OK-432-induced anti-cancer host response. Establishment and clinical use of the methodology for human cancer therapy by utilizing TLR signaling is greatly expected.
Insights
Toll-like receptor (TLR) signaling enhances anti-cancer immunity. TLR4 signaling is crucial for immune responses to novel immunopotentiators, showing promise for cancer therapy.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Augmenting host anti-cancer responses is vital for effective cancer treatment.
- Toll-like receptors (TLRs) recognize pathogens and are implicated in anti-cancer immunity.
- TLR2 and TLR4 mediate dendritic cell maturation and cytokine induction by BCG-CWS.
- TLR9 recognizes CpG-DNA, inducing Th1 responses and showing potential in cancer therapy.
Purpose of the Study:
- To investigate the role of TLR signaling in anti-cancer immunity.
- To evaluate novel immunopotentiators for their ability to induce anti-cancer effects.
- To explore the involvement of TLR4 and MD-2 in the host response to OK-432 in oral cancer patients.
Main Methods:
- Investigated immunopotentiators including a lipoteichoic acid-related molecule and a plant-derived protein.
- Conducted basic experiments to assess TLR4 signaling in TLR-mediated anti-cancer immunity.
- Performed clinical examinations in oral cancer patients to evaluate TLR4 and MD-2 involvement.
Main Results:
- Two novel molecules were identified that induce Th1 response and exhibit strong in vitro and in vivo anti-cancer effects.
- TLR4 signaling was found to be intimately involved in the anti-cancer immunity induced by these immunopotentiators.
- Clinical data suggested that both TLR4 and MD-2 are required for the OK-432-induced anti-cancer host response in oral cancer.
Conclusions:
- TLR signaling, particularly via TLR4, plays a significant role in mediating anti-cancer host responses.
- Novel immunopotentiators targeting TLRs hold promise for developing new cancer therapies.
- Further clinical application of TLR-targeting methodologies is expected for human cancer treatment.