title: Mechanism of antitumor effect on mouse hepatocellular carcinoma by intratumoral injection of OK-432, a streptococcal preparation.
abstract: Intratumoral (i.t.) injection of OK-432, a streptococcal preparation, into implanted tumors of mouse hepatocellular carcinoma (MIH-2) showed antitumor effect including tumor eradication. Intraperitoneal administration of same dose OK-432 did not exhibit tumor suppressive effect. In vitro cytotoxic test suggested that direct cytotoxic effect of OK-432 was not associated with antitumor activity by i.t.-OK-432 treatment. It was also found that Toll-like receptor 4 signaling was not involved in i.t.-OK-432 treatment. Three mice out of five, which had shown tumor eradication by i.t.-OK-432 treatment did not reject re-challenge of MIH-2 cells. Splenocytes from i.t.-OK-432 treated mice did not produce IFN-gamma by stimulation with MIH-2 cells in vitro, but produced abundant IFN-gamma by stimulation with OK-432. Immunofluorescence microscopy demonstrated that CD4+T cells, but not CD8+T cells, infiltrated to i.t.-OK-432 treated tumor tissue produced IFN-gamma. Tumor-infiltrating CD4+T cells from i.t.-OK-432 treated tumor tissue produced IFN-gamma by in vitro stimulation with OK-432 higher than those from untreated tumor tissue. IFN-gamma directly induced apoptosis of MIH-2 cells in vitro. Collectively, i.t.-OK-432 treatment induced priming of CD4+T cells to antigenecity of OK-432, and repetitive i.t.-OK-432 treatment induced IFN-gamma production from OK-432-sensitized CD4+T cells in tumor site, leading to apoptosis of MIH-2 cells susceptible to IFN-gamma.
authors.affiliation: Department of Oncology, Institute of DNA Medicine, Jikei University School of Medicine, Tokyo, Japan. sahya@jikei.ac.jp
authors.forename: Sadamu
authors.initials: S
authors.lastname: Homma
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Sagawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Komita
authors.forename: Shigeo
authors.initials: S
authors.lastname: Koido
authors.forename: Eijiro
authors.initials: E
authors.lastname: Nagasaki
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Ryoma
authors.forename: Masato
authors.initials: M
authors.lastname: Okamoto
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor / Q000187:drug effects / Q000473:pathology; D004354:Drug Screening Assays, Antitumor; D006084:Graft Rejection; D007114:Immunization; D015552:Injections, Intralesional; D007274:Injections, Intraperitoneal; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009368:Neoplasm Transplantation; D010844:Picibanil / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D013297:Streptococcus pyogenes; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000502:physiology
chemical_list: D000276:Adjuvants, Immunologic; D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D010844:Picibanil; D007371:Interferon-gamma