The effects of various
sugars and
sugar derivatives on lung colonization (i.e., metastatic deposition) of the highly metastatic BL6 clone of B16 mouse
melanoma cells in syngeneic mice were studied, based on the assumption that
carbohydrate structures, particularly those with a Gal terminus, play a crucial role in defining the metastatic potential of B16 cells. After incubation with
sugar compounds (usually at 0.1 M concentration),
tumor cells were injected via the tail vein into 8-week old female mice. Mice were sacrificed after 18-21 days, and
tumor cell colonies in lung were counted under a dissecting microscope. Only
methyl beta-D-lactoside and
lacto-N-tetraose caused significant reduction (35-45% and 36%, respectively) of metastatic deposition compared to controls.
Methyl beta-D-lactoside did not exhibit a growth inhibitory effect on BL6
tumor cells, as determined by several methods: in vitro [3H]
thymidine incorporation assay, in vitro plating in RPMI-1640 medium culture under physiological conditions followed by cell counting, and in vivo subcutaneous inoculation of age-matched C57/BL mice followed by
tumor measurement. These results indicate that the inhibitory effect of
methyl beta-D-lactoside on
tumor deposition was not related to its effect on
tumor cell growth.