Characterization of a sialic-acid-rich mucus glycoprotein secreted by a premalignant human colorectal adenoma cell line.
The human colonic cell line PC/AA, derived from an adenoma, retains in vitro colonic cell differentiation, notably the production of mucus glycoproteins. The PC/AA adenoma cells produce an extracellular gel layer in culture. The PC/AA gel could be isolated by extraction of the cell cultures with guanidine hydrochloride. The extracted material was purified by gel filtration and caesium chloride density-gradient centrifugation and showed properties typical of mucus glycoproteins, namely, a carbohydrate content above 60% of dry weight rich in N-acetylgalactosamine and sialic acid and low in mannose; an amino acid composition with high serine threonine and proline content; a molecular weight above 1,000 kDa on Sepharose CL 4B chromatography and on SDS-polyacrylamide gel electrophoresis under reducing conditions (greater than 200 kDa); a buoyant density of approximately 1.48 g/ml and the release of oligosaccharides by the alkaline beta-elimination reaction. Comparison of the gel mucus glycoprotein purified from premalignant PC/AA cells with normal human colon mucin showed that it has a higher sialic acid content. This suggests that higher sialic acid levels may precede the development of malignancy.
Corfield
A P
AP
University Department of Medicine, Bristol Royal Infirmary, UK.
Clamp
J R
JR
Casey
A D
AD
Paraskeva
C
C
D000236:Adenoma / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism*; D004229:Dithiothreitol; D019791:Guanidine; D006146:Guanidines; D006801:Humans; D009077:Mucins / Q000737:chemistry* / Q000378:metabolism; D009093:Mucus / Q000737:chemistry; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism; D011230:Precancerous Conditions / Q000378:metabolism*; D012794:Sialic Acids / Q000032:analysis* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D006146:Guanidines; D009077:Mucins; D009363:Neoplasm Proteins; D012794:Sialic Acids; D019791:Guanidine; D004229:Dithiothreitol