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Tumor-immunotherapeutic efficacy of Serratia marcescens polyribosomes
Abstract:
The ability of polyribosomes, obtained from several bacterial species, to suppress the development of cutaneous SaD2 fibrosarcomas in DBA/2 mice were evaluated. Suppression of tumor appearance depended upon the tumor load at the time of treatment, dose of polyribosomes, and species source of polyribosomes, with Serratia marcescens being superior to Escherichia coli, Streptococcus pneumoniae, Mycobacterium bovis (Pasteur), Mycobacterium smegmatis, and Propionibacterium acnes (formerly Corynebacterium parvum). A single injection of 5 or 50 microgram of Serratia polyribosomes at the tumor site 72 hr after the intradermal administration of 1.5 X 10(3) SaD2 cells resulted in 66 to 95% survival. All untreated animals expired within 50 days. Tumor suppression occurred at both flank and footpad sites. Presensitization with polyribosomes and incorporation of polyribosomes into adjuvant were not required for the tumor-suppressive effect. Treatment of Serratia polyribosomes with RNase or pronase reduced the number of survivors. Endotoxin was not detectable with the Limulus amebocyte lysate assay.
Insights
Bacterial polyribosomes, particularly from Serratia marcescens, effectively suppressed fibrosarcoma tumor growth in mice. This discovery offers a novel approach to cancer treatment by targeting tumor development with bacterial components.
Area of Science:
- Immunology
- Microbiology
- Oncology
Background:
- Cutaneous fibrosarcomas pose a significant challenge in oncology.
- Bacterial components are known to modulate immune responses.
- The potential of bacterial polyribosomes in cancer therapy remains largely unexplored.
Purpose of the Study:
- To evaluate the efficacy of bacterial polyribosomes in suppressing the development of cutaneous SaD2 fibrosarcomas in DBA/2 mice.
- To identify bacterial species that yield the most effective polyribosomes for tumor suppression.
- To determine factors influencing the tumor-suppressive activity of polyribosomes.
Main Methods:
- Polyribosomes were isolated from various bacterial species, including Serratia marcescens, Escherichia coli, and others.
- These polyribosomes were administered to DBA/2 mice with induced SaD2 fibrosarcomas.
- Tumor development and animal survival rates were monitored following polyribosome treatment.
- Treatments involved varying doses and administration sites, and polyribosomes were subjected to enzymatic degradation (RNase, pronase).
Main Results:
- Serratia marcescens polyribosomes demonstrated superior tumor suppression compared to other bacterial sources.
- Tumor suppression was dependent on tumor load, polyribosome dose, and bacterial species.
- A single injection of 5 or 50 µg of Serratia polyribosomes resulted in 66-95% survival.
- Untreated control animals all expired within 50 days.
- Polyribosome efficacy was observed at both flank and footpad tumor sites.
- RNase or pronase treatment reduced the number of surviving animals, indicating the involvement of RNA and protein components.
- Endotoxin was not detected in the polyribosome preparations.
Conclusions:
- Bacterial polyribosomes, especially from Serratia marcescens, possess significant tumor-suppressive properties against fibrosarcomas in mice.
- The efficacy is influenced by dose, tumor burden, and bacterial origin, with RNA and protein components being crucial.
- This suggests a potential therapeutic strategy for cancer treatment leveraging bacterial-derived molecules.