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The cell surface glycosylation profiles of a liver metastatic colon carcinoma variant cell line, SL4 cells previously selected from colon 38 cells in vivo for liver colonization were investigated. Flowcytometric analysis was performed with 7 plant lectins and 10 carbohydrate specific monoclonal antibodies. The results showed that peanut agglutinin (PNA), Sambucus nigra agglutinin, Ulex europeus agglutinin-I, anti-LeX, anti-LeY, and anti-Le(b) antibodies bound to the parental colon 38 cells but not to SL4 cells. Another variant cell line was selected in vitro for the paucity of cell surface PNA-binding sites using a magnetic cell sorter and was designated as 38-N4 cells. The binding profiles of plant lectins and carbohydrate-specific antibodies to 38-N4 cells were very similar to those of SL4 cells. After intrasplenic injections, metastatic ability of 38-N4 cells was higher than that of colon 38 cells. PNA binding to SL4 cells and 38-N4 cells was detected after sialidase treatment of these cells, indicating increased sialylation of Thomsen-Friedenreich antigen in these cells. The mRNA levels of sialyltransferases, ST3Gal I, ST3Gal II, ST6GalNAc I, and ST6GalNAc II, were compared. The level of ST3Gal II mRNA was elevated in both SL4 cells and 38-N4 cells, whereas the level of ST6GalNAc II mRNA was elevated in 38-N4 cells compared with colon 38 cells. According to the expression array analysis, there are other glycosyltransferase genes differentially expressed between SL4 and colon 38 cells, yet their involvement in the altered glycosylation in these cells is unclear.

Clinicopathological observations have revealed that the expression level of a carbohydrate antigen recognized by the monoclonal antibody (mAb) FH6 in colorectal carcinomas is higher at advanced stages than at early stages. The present study aimed to elucidate whether human colon carcinoma cell surface glycans recognized by mAb FH6 determine the ability of these cells to adhere to sections of human liver. Variant human colon carcinoma cell lines selected for high and low binding of mAb FH6 were compared with respect to their adhesive capacity. The cells expressing the higher level of FH6 binding also showed a greater ability to adhere to liver sections. This adhesion was not blocked by anti-E-selectin monoclonal antibodies, but pretreatment of the carcinoma cells with endo-beta-galactosidase significantly reduced both cell surface binding of mAb FH6 and the ability of the cells to adhere to liver sections. Our observations suggest that endo-beta-galactosidase-sensitive carbohydrate chains containing an epitope recognized by mAb FH6 play an important role in the adhesion of human colon carcinoma cells to human liver sections. Whether these interactions have any relationship to the mechanism(s) of liver metastasis remains to be elucidated.