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Antitumor activity of Propionibacterium acnes (Corynebacterium parvum) and isolated cytoplasmic fractions
Abstract:
The tumor-inhibitory effect of an intralesional injection of Propionibacterium acnes was of limited duration ("finite"). Our model was the DBA/2 syngeneic mouse injected with P815 mastocytoma cells (5 X 10(5)) into each rear footpad; only the left was treated, leaving the right as a "pseudometastasis." The finite effect occurred at approximately 21 days after the first treatment. Subsequent i.p. treatments with P. acnes did not alter this effect, although they increased mean survival time. With one footpad tumor, we achieved 22% cures with complete regression and no sign of metastatic growth. A RNA fraction from P. acnes produced inhibition of tumor growth, but crude cell walls and cell walls treated with Pronase had no effect. A P. acnes cytoplasmic fraction with tumor-inhibitory activity was pelleted by high-speed centrifugation; this fraction inhibited P815 mastocytoma as fully as whole cells injected in one-fifth the dose on a nitrogen basis and did not cause a local inflammatory reaction. The activity of the pellet also differed from whole cells in that it was equally inhibitory to the pseudometastasis in the contralateral right rear footpad. The cytoplasmic fraction apparently contained at least two active components since activity was obtained at two dilution levels. Such activity was relatively stable at 5 degrees, but it was unstable at -30 degrees.
Insights
Intralesional Propionibacterium acnes injections showed temporary tumor inhibition. A P. acnes cytoplasmic fraction demonstrated potent, localized tumor suppression without inflammation, offering a promising therapeutic avenue.
Area of Science:
- Immunology
- Oncology
- Microbiology
Background:
- Intralesional Propionibacterium acnes (P. acnes) injections exhibit transient tumor-inhibitory effects.
- Understanding the specific components responsible for this activity is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the tumor-inhibitory mechanisms of P. acnes.
- To identify the active fraction of P. acnes responsible for tumor suppression.
- To evaluate the efficacy and characteristics of this active fraction.
Main Methods:
- Utilized a DBA/2 syngeneic mouse model with P815 mastocytoma footpad tumors.
- Administered intralesional P. acnes injections and evaluated treatment effects on primary tumors and contralateral "pseudometastases".
- Fractionated P. acnes components (RNA, cell walls, cytoplasmic fraction) and assessed their tumor-inhibitory activity via high-speed centrifugation.
Main Results:
- Intralesional P. acnes achieved 22% cures with complete tumor regression and no metastasis.
- A P. acnes cytoplasmic fraction inhibited P815 mastocytoma growth effectively at a lower dose than whole cells and without local inflammation.
- This cytoplasmic fraction also inhibited contralateral "pseudometastasis" growth, suggesting systemic or potent local effects.
Conclusions:
- A P. acnes cytoplasmic fraction possesses significant tumor-inhibitory activity.
- This fraction is a potent candidate for further investigation in cancer therapy due to its efficacy and reduced inflammatory potential.
- The activity of the cytoplasmic fraction is relatively stable at 5 degrees Celsius but unstable at -30 degrees Celsius.