Tag Archives: metastasis

Antitumor effects of residual tumor after cryoablation: the combined effect of residual tumor and a protein-bound polysaccharide on multiple liver metastases in a murine model

Masato Urano, Chihiro Tanaka, Yasuyuki Sugiyama, Kiichi Miya, and Shigetoyo Saji*

Cryoablation is a low-invasive surgical treatment for malignant tumors. It may induce an immunological response leading to the eradication of distant metastases or alternatively it might promote the growth of residual tumors. In this paper we confirm the occurrence of both phenomena and we describe the preventive effect of a protein-bound polysaccharide preparation. Metastatic liver tumors were produced in BALB/c mice by the intrasplenic inoculation of colon 26 cells and cryoablation was carried out usingliquid nitrogen ()170C) applied by a contact method. The value of combiningcryoablation with administration of the polysaccharide preparation in the prevention of growth of residual tumors was investigated. It was shown that the number of metastatic liver nodules and the size of the primary tumor at the site of inoculation in the spleen were significantly lower when the volume that was frozen was small. The production by splenocytes of the tumor necrosis factor TNF-a, interferon INF-c, and the interleukins IL-4 and IL-10 increased significantly after freezing and thawing of the tumor tissue. The polysaccharide treatment significantly reduced the production of IL-4 and IL-10 followingcryoablation; the production of TNF-a and INF-c was slightly promoted; the natural killer and cytotoxic T-cell activities of splenocytes were slightly enhanced. It was concluded that the polysaccharide preparation was beneficial by suppressing IL-4 and IL-10 production and might inhibit the growth of residual tumor that is sometimes induced by large-volume cryoablation.

Antimetastatic effect of PSK, a protein-bound polysaccharide, against the B16-BL6 mouse melanoma.

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.