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Antitumor action of an acidic glycoprotein (SAGP) from Streptococcus pyogenes in mice
J Yoshida1, S Takamura, S Suzuki
1Department of Pharmacology, Kanazawa Medical University, Ishikawa, Japan.
Abstract:
We have shown that an acidic glycoprotein (SAGP) isolated from a cell-free extract of Streptococcus pyogenes (Su strain) prolonged the life-span of Ehrlich ascites carcinoma (EAC)-bearing mice. The present study shows that the life-span prolonging effect of SAGP in EAC-bearing mice was reduced by whole body X-irradiation before EAC inoculation. SAGP (500 micrograms protein/mouse/day X 4, i.p.) also showed a life-span prolonging effect (T/C (%) = 169) on Meth A fibrosarcoma (Meth A)-bearing mice, but the effect of SAGP was abrogated by an i.p. pretreatment of the host with carrageenan, an antimacrophage agent. The spleen cells from the Meth A-inoculated and SAGP-treated mice were found to have a considerable cytostatic activity by a 3H-thymidine incorporation assay. But the activity disappeared in the presence of carrageenan. These results suggest that the in vivo antitumor effects of SAGP are mediated through its immunomodulating action.
Insights
An acidic glycoprotein (SAGP) from Streptococcus pyogenes extends mouse lifespan against cancer. Its antitumor effects appear mediated by immune system modulation, as shown by reduced efficacy with X-irradiation and carrageenan treatment.
Area of Science:
- Immunology
- Oncology
- Microbiology
Background:
- An acidic glycoprotein (SAGP) from Streptococcus pyogenes demonstrates life-extending properties in cancer models.
- Previous research indicated SAGP's efficacy in prolonging survival in Ehrlich ascites carcinoma (EAC)-bearing mice.
Purpose of the Study:
- To investigate the mechanism behind the in vivo antitumor effects of SAGP.
- To determine if SAGP's efficacy is dependent on immune system function.
Main Methods:
- Ehrlich ascites carcinoma (EAC) and Meth A fibrosarcoma (Meth A) mouse models were utilized.
- SAGP efficacy was assessed following whole-body X-irradiation and carrageenan pretreatment.
- Spleen cell cytostatic activity was measured using a 3H-thymidine incorporation assay.
Main Results:
- X-irradiation significantly reduced SAGP's life-prolonging effect in EAC-bearing mice.
- Carrageenan, an antimacrophage agent, abrogated SAGP's efficacy in Meth A-bearing mice.
- Spleen cells from SAGP-treated mice exhibited cytostatic activity, which was abolished by carrageenan.
Conclusions:
- The in vivo antitumor effects of SAGP are likely mediated by its immunomodulating actions.
- SAGP's efficacy appears to be dependent on macrophage activity and overall immune response.