Cell-surface oligosaccharides expressed by phenotypically distinct sublines of the Dunning 3327 rat prostate cancer.

Cell-surface glycoconjugates of normal epithelia are recognized to alter during ontogeny and oncogenesis [ 11. Such changes affcct intercellular contact and modify patterns of organ colonization during invasion and metastasis. A particularly common feature of epithelial malignancies is an increased sialyation of cell surface oligosaccharide determinants. In a study of primary and metastatic human breast canccr, Foster & Neville 121 identified a population of plasma membrane glycoproteins in which sialylation correlated with aberrant intracellular processing. Recently, Abel et al. [3] examined cloned tumours of the Dunning rat prostate cancer model. They demonstrated that specific differences in structure and intracellular expression of oligosaccharide determinants by phenotypically distinct clones of the tumours in vivo were both consistent and specific. In this model, sialylation of glycoprotein oligosaccharides appeared to be a common feature o f all the tumours examined. Although a valuable technique, immunohistochemistry of intact tissues does not provide adequate information about events and structures occurring on the surfaces of individual tumour cells. To obtain quantitative information about the expression of oligosaccharide determinants by individual tumour cells, we have employed fluorescence-activated cellsorting to analyse lectin binding by two phenotypically distinct tumours within the Dunning prostate cancer model. Cell lines AT-2.1 and AT-3.1 of the R-3327 Dunning rat prostate cancer model exhibit low-metastatic and highlymetastatic phenotypes, respectively [ 41. These were obtaincd from Dr J. lsaacs (Johns Hopkins Cancer Center, Baltimore. U.S.A.). The cells were cultured in RPMI-1640 containing 2 mM-L-glutamine, 1O0h ( v / v ) fetal calf serum, 250 n M dexamethasone and 100 units/ml each of penicillin G and streptomycin, together with 2 mu-Fungizone. Cultures were maintained at 37"C, 5% CO, in air and 100% humidity. At confluence, cells were harvested using 0.025"h (w/v) trypsin in 10 mwsodium phosphate buffer (pH 7.4) without Ca?+ or Mg?+. Aliquots of 5 x 10' cells each were stained with a panel of fluorescein-conjugated lectins for 1 h at 4°C. The