Involvement of Toll-like receptor 4 signaling in interferon-gamma production and antitumor effect by streptococcal agent OK-432.

Abstract

BACKGROUND:

The streptococcal agent OK-432 has been used for immunotherapy of head and neck cancer, among other malignancies, but its mechanism of action is unknown. Because the Toll-like receptor 4 (TLR4)/MD-2 complex is important in enabling the mammalian immune system to recognize bacterial components, we investigated whether expression of the TLR4 and MD-2 genes is associated with OK-432-induced anticancer immunity.

METHODS:

Peripheral blood mononuclear cells (PBMCs) from 28 patients with head and neck cancer were analyzed for TLR4 and MD-2 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR) analysis. PBMCs were treated in vitro with OK-432 or with OK-PSA (a lipoteichoic-acid-related molecule that is an active component of OK-432), and interferon-gamma (IFN-gamma) mRNA expression, an immune response measure, was analyzed by RT-PCR. Patient sera collected 24 hours after OK-432 administration were examined for IFN-gamma protein using an enzyme-linked immunosorbent assay. Lewis lung carcinoma-bearing wild-type C57BL/6 and TLR4-deficient mice (four mice per group) received intraperitoneal injections of OK-432, and tumor volumes and sera IFN-gamma levels were measured over time. All statistical tests were two-sided.

RESULTS:

Twenty patients expressed both TLR4 and MD-2. Expression of TLR4 and MD-2 genes was associated with the in vivo IFN-gamma induction in 19 patients administered OK-432 (Fisher's exact test P<.001). Although both OK-432 and OK-PSA induced IFN-gamma expression from PBMCs in vitro, expression of TLR4 and MD-2 was associated only with IFN-gamma expression induced by OK-PSA (P<.001). In vivo intraperitoneal administration of OK-432 resulted in an increase of IFN-gamma in sera from wild-type mice but not in sera from TLR4-deficient mice. Tumors in wild-type mice treated with OK-432 were statistically significantly smaller than those in mice treated with saline (P =.007). By contrast, in TLR4-deficient mice, there was no difference in tumor volume between the two treatment groups.

CONCLUSIONS:

TLR4 and MD-2 may mediate OK-432-induced anticancer immunity.

• Authors: Masato Okamoto, Tetsuya Oshikawa, Tomoyuki Tano, Go Ohe, Sachiko Furuichi, Hidetomo Nishikawa, Sharif Uddin Ahmed, Sachiko Akashi, Kensuke Miyake, Osamu Takeuchi, Shizuo Akira, Yoichiro Moriya, Shuzo Matsubara, Yoshiki Ryoma, Motoo Saito, Mitsunobu Sato
• Journal: Journal of the National Cancer Institute (J Natl Cancer Inst) Vol. 95 Issue 4 Pg. 316-26 (Feb 19 2003) ISSN: 0027-8874 [Print] United States
• PMID: 12591988 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Antigens, Surface
• Antineoplastic Agents
• Drosophila Proteins
• LY96 protein, human
• Lymphocyte Antigen 96
• Membrane Glycoproteins
• RNA, Messenger
• RNA, Neoplasm
• Receptors, Cell Surface
• TLR4 protein, human
• Toll-Like Receptor 4
• Toll-Like Receptors
• Picibanil
• Interferon-gamma
• Luciferases
• Polymyxin B

Topics

• Aged
• Animals
• Anti-Bacterial Agents (pharmacology)
• Antigens, Surface (genetics, metabolism)
• Antineoplastic Agents (pharmacology)
• Drosophila Proteins
• Enzyme-Linked Immunosorbent Assay
• Female
• Head and Neck Neoplasms (chemistry, drug therapy, immunology)
• Humans
• Injections, Intraperitoneal
• Interferon-gamma (biosynthesis, blood, drug effects)
• Luciferases (analysis)
• Lymphocyte Antigen 96
• Male
• Membrane Glycoproteins (deficiency, drug effects, immunology, metabolism)
• Mice
• Mice, Inbred C57BL
• Middle Aged
• Picibanil (pharmacology)
• Polymyxin B (pharmacology)
• RNA, Messenger (analysis)
• RNA, Neoplasm (analysis)
• Receptors, Cell Surface (deficiency, drug effects, immunology, metabolism)
• Reverse Transcriptase Polymerase Chain Reaction
• Signal Transduction (drug effects)
• Toll-Like Receptor 4
• Toll-Like Receptors