Cell surface properties of high- and low-metastatic cell lines selected from a spontaneous mouse lung carcinoma

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Abstract
The surface oligosaccharide residues, glycoproteins and sialyl components of CMT64 lung carcinoma cells and high‐metastatic sublines CMT167 and CMT181 have been studied in culture. (I) The total cellular sialic acid content did not differ appreciably between the three lines. However, the accessibility of surface sialyl groups, measured by metabolic incorporation of [3H]NAcmannosamine followed by neuraminidase hydrolysis, was decreased from 42% in CMT64 to 25% hydrolyzed in CMT181. (2) The major plasma membrane glycoproteins of the lines were radiolabelled by lactoperoxidase iodination, metabolic incorporation of [3H]fucose or labelling in the terminal sialyl residues by the NalO4‐NaB[3H]4 method and the labelled glycoproteins were analyzed by two‐dimensional gel electrophoresis. Each labelling technique identified a complex pattern of glycoproteins including a prominently labelled group of high‐molecular‐weight acidic sialoglycoproteins: GP200/4.9–5.1 (apparent molecular weight ×10−3/pI of iodoprotein); GP150/5.1–5.6; GP130/5.0–5.6; GP110/5.0; GP100/4.8 and GP100/5.0–5.4. (3) The neuraminidase‐susceptible glycoproteins on CMT64 and CMT181 were identified in the isoelectric focusing separation of the two‐dimensional gel separation by the charge difference caused by desialylation. The glycoproteins most susceptible to neuraminidase were the high‐molecular‐weight acidic glycoproteins which showed marked charge heterogeneity: GP150/5.1–5.6, GP130/5.0–5.6; GP100/5.0–5.4 and GP100/4.8. (4) Using these procedures we did not detect modifications between CMT181 and CMT64 and we conclude that the cultured cells of the sublines do not display marked surface glycoprotein alterations that reflect their enhanced spontaneous metastatic potential.