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[Preliminary study on skeletal muscle derived tumor suppressor]
Objective:
To investigate the effect of new born rat skeletal muscle conditioned medium (MCM) on proliferation of tumor cells, and its physicochemical characteristics and mechanisms of action.
Methods:
The effects of MCM were tested on a variety of cells by MTT assay. MCM was also tested following ultrafiltration, boiling at 100 degrees C and treatment with trypsin. Morphology and apoptosis of the MCM-treated cells were examined.
Results:
Proliferation of mouse myeloma SP2/0, rat carcino-sarcoma Walker 256, and tumor cell lines of human origin, including leukemia K562 and HL-60, colon adenocarcinoma LS-174-T, prostatic carcinoma PC3-M, and lung adenocarcinoma with low(PLA801-C) and high(PLA801-D) metastatic potential were significantly decreased when cultured with MCM(P < 0.01-0.05) in a dose-dependent manner. The proliferation of normal cells(RGP-2 rabbit joint epiphysial disk cells) was not affected by MCM. Proliferation of the lung adenocarcinoma with high metastatic potential was more susceptible to the growth inhibitory effect of MCM as compared to that with low metastatic potential. On ultrafiltration, the inhibitory activity of MCM existed in the fraction with a molecular weight < or = 10,000. It was trypsin resistant but thermolabile. Apoptosis was not seen but the cytoplasmic membrane of tumor cells was destroyed after cultured in MCM.
Conclusion:
Rat skeletal muscle cells produce low molecular weight tumor suppressor(s) capable of selectively inhibiting tumor cell proliferation in vitro. Its activity is neither species- nor tumor-specific. The skeletal muscle derived tumor suppressor(s) may play a key role in the rarity of tumor metastases in skeletal muscles.
Insights
Newborn rat skeletal muscle conditioned medium (MCM) contains low molecular weight tumor suppressors that inhibit tumor cell proliferation without affecting normal cells. This suggests a role for skeletal muscle in preventing tumor metastasis.
Area of Science:
- Biochemistry
- Cell Biology
- Oncology
Context:
- Skeletal muscle conditioned medium (MCM) is a biological fluid containing secreted factors.
- Tumor cell proliferation and metastasis are critical aspects of cancer research.
- Understanding endogenous tumor suppressors is key to developing novel cancer therapies.
Purpose:
- To investigate the anti-proliferative effects of MCM on various tumor cell lines.
- To characterize the physicochemical properties of the active components in MCM.
- To elucidate the mechanism of action of MCM on tumor cells.
Summary:
- MCM significantly inhibited the proliferation of diverse tumor cell lines, including myeloma, sarcoma, leukemia, colon, prostate, and lung adenocarcinoma cells, in a dose-dependent manner.
- Normal rabbit joint cells were unaffected, indicating selective toxicity towards tumor cells.
- The inhibitory activity was attributed to low molecular weight (<10,000 Da) factors that were trypsin-resistant but heat-labile, causing tumor cell membrane destruction without inducing apoptosis.
Impact:
- Identifies novel, low molecular weight tumor suppressors derived from skeletal muscle.
- Demonstrates selective inhibition of tumor cell growth and potential anti-metastatic properties.
- Suggests a potential endogenous mechanism contributing to the low incidence of skeletal muscle metastases.