Possible role of immune surveillance at the initial phase of metastasis produced by B16BL6 melanoma cells

Abstract

The relationship among the real-time trafficking of lung metastatic B16BL6 cells, metastatic potential, and the injected number of the cells was examined, since the smaller the number of tumor cells injected, the more clearly the immune defense may be observed. When 1U U10 6 or 1U U10 5 B16BL6 cells were injected into mice via the tail vein, both numbers of cells accumulated in the lung at a similar rate : there was an approximately 10-fold difference in the number of accumulated cells between the two doses. Elimination from the lung was not dependent on the cell number but on the proportion of accumulated cells. However, the injection of 1U U10 4 cells resulted in lung accumulation less than one-tenth of that obtained with 1U U10 5 cell injection. Metastasis was observed when 1U U10 5 or 1U U10 6 B16BL6 cells were injected, but not after injection of 1U U10 4 cells. To clarify the roles of the immune defense system at the initial phase of metastasis, we challenged macrophagedepleted mice with 1U U10 4 tumor cells. Treatment of mice with 2-chloroadenosine prior to the tumor cell challenge cancelled the suppression of not only metastasis but also the lung accumulation. Furthermore, the administration of 2-chloroadenosine following the tumor cell challenge had little effect on the metastatic potential. These results suggest that the immune surveillance whose action was obvious at the low dose of challenged tumor cells functions strongly at the initial phase but not at the advanced stages of the metastatic process, and that macrophages play an important role in the suppression of metastasis.z 2000 Federation of European Biochemical Societies.

Heparin and cancer revisited: Mechanistic connections involving platelets, P-selectin, carcinoma mucins, and tumor metastasis

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Chemoprevention of Tumor Metastasis by Liposomal .BETA.-Sitosterol Intake

“…We previously demonstrated that the intravenous injection of a lower number of metastatic tumor cells failed to form metastatic colonies in the target organ, whereas a larger number completed tumor metastasis. 1) In addition, pre-treatment of 2-chloroadenosine, which weakened the mouse's immune strength, impaired the initial stage of tumor metastasis fewer tumor cells were injected. 2) These findings indicate that immune surveillance in the host plays an important role in the initial phase of tumor metastasis.…”

Enhanced Experimental Tumor Metastasis with Age in Senescence-Accelerated Mouse

“…The previous study indicated that the early accumulation of metastatic tumor cells in the target organ strongly foretold the eventual tumor metastasis in experimental metastatic models. 9,18) The accumulation of [ 18 F]FDG-labeled K1735M2 cells in the lung in young and aged mice was observed: Lung is known as the target organ for K1735M2 cells after their injection into the bloodstream. Figure 2a shows the accumulated image every 15 min in the lung, and it is apparent that the tumor cells gradually began to remain in the lung of aged mice more than in that of young mice 90 min after injection.…”

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