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Antimetastatic effect of PSK, a protein-bound polysaccharide, against the B16-BL6 mouse melanoma
K Matsunaga1, M Ohhara, Y Oguchi
1Biomedical Research Laboratories, Kureha Chemical Industry, Tokyo, Japan.
Abstract:
We examined the effect of PSK, a protein-bound polysaccharide, upon in vivo metastasis and in vitro invasion of the B16-BL6 mouse melanoma cells. (1) PSK suppressed in vivo artificial and spontaneous lung metastases of B16-BL6 in C57BL/6 mice. (2) PSK in a dose-dependent fashion suppressed in vitro invasion and chemotaxis of the tumor cells using filters coated with a reconstituted basement membrane. (3) PSK had little effect on DNA synthesis in tumor cells in vitro, but suppressed tumor cell adhesion to, degradation of, and haptotaxis to components of the basement membrane. (4) PSK suppressed the binding of tumor cells to components of the basement membrane. These findings suggest that PSK may suppress metastasis through inhibition of tumor cell invasion and that this effect is the result of interactions between PSK and components of the basement membrane.
Insights
Protein-bound polysaccharide (PSK) inhibits melanoma metastasis and invasion. PSK reduces tumor cell binding to and degradation of the basement membrane, suggesting a novel anti-metastatic mechanism.
Area of Science:
- Oncology
- Immunology
- Biochemistry
Background:
- Metastasis is a complex process involving tumor cell invasion and migration.
- The basement membrane plays a critical role in regulating tumor cell invasion.
- Protein-bound polysaccharide (PSK) is a known immunomodulator with potential anti-cancer properties.
Purpose of the Study:
- To investigate the effect of PSK on the in vivo metastasis and in vitro invasion of B16-BL6 mouse melanoma cells.
- To elucidate the mechanisms by which PSK may inhibit tumor cell invasion and metastasis.
Main Methods:
- In vivo studies using C57BL/6 mice with artificial and spontaneous B16-BL6 lung metastases.
- In vitro invasion and chemotaxis assays using reconstituted basement membrane-coated filters.
- Assessment of tumor cell adhesion, DNA synthesis, degradation, and haptotaxis to basement membrane components.
Main Results:
- PSK significantly suppressed both artificial and spontaneous lung metastases of B16-BL6 melanoma cells in mice.
- PSK demonstrated a dose-dependent inhibition of in vitro tumor cell invasion and chemotaxis.
- PSK reduced tumor cell adhesion to, degradation of, and haptotaxis towards basement membrane components.
- PSK had minimal impact on tumor cell DNA synthesis.
Conclusions:
- PSK effectively suppresses melanoma metastasis and invasion, both in vivo and in vitro.
- PSK's anti-metastatic effects are likely mediated by inhibiting tumor cell interactions with the basement membrane.
- These findings highlight PSK as a potential therapeutic agent for preventing cancer metastasis.