Fulvio Perini

ALTERED EXPRESSION OF SIALYLATED CARBOHYDRATE ANTIGENS IN HT29 COLONIC CARCINOMA CELLS

To determine whether cell growth conditions impacted carbohydrate expression, HT29 cells were gradually transferred from a conventional glucose-containing media to a glucose-free galactose containing media. Indirect immunofluorescence on acetone fixed cells showed increased expression of sialyl Lewis A antigen (CA19-9), sialyl Lewis C (DUPAN2) and Tn/sialyl-Tn on the surface of HT29 cells grown in the glucose-free galactose containing media compared to those grown in the glucose containing media. Sialyltransferases responsible for the synthesis for these sialylated epitopes were increased in the galactose-fed HT29 cells. Media overlying the cells was subjected to isopycnic ultracentrifugation in cesium chloride and the fractions derived from both glucose and galactose media with equivalent buoyant densities of 1.56 g/L, which are predicted to contain mucin glycoforms, were further separated by HPLC using a Mono-Q anion exchange column. The chromatograph of eluent from the sample derived from the cells growing in the galactose containing media showed an increased peak that reacted with the anti-sialyl Lewis A antibody, CA19-9. These results show that alteration of in vitro culture conditions may cause HT29 colonic carcinoma cells to alter the expression of sialylated carbohydrates.

Folding of the β-Subunit of hCG and Its Role in Assembly of the α-β Heterodimer

It has been known for some time that the assembly of the α- and β-subunits of human chorionic gonadotropin (hCG) within cells that produce it is not totally efficient. As a result, uncombined α- and β-subunits, as well as α-β heterodimer, are secreted (1–3). Efficiency of α-β assembly in vitro, using purified urinary forms of the subunits, has also been reported to be low, with a kd of 0.6 μM (4).

A novel adhesion factor produced by hamster pancreatic cancer cell line is effective on normal and carcinoma cell lines of different species.

SummaryAn adhesion factor, produced by the hamster pancreatic cancer cell line PC-1.0, was tested for its efficiency in promoting the in vitro adhesion of normal and tumor cells (pancreas, lung, kidney, colon, breast, skin, prostate, neuroblast, melanocyte) derived from human, monkey, bovine, hamster, and rat sources. Using a modification of the dimethylthyazol diphenyl tetrazolium (MTT) assay, the factor was found to induce adhesion in all cell lines in a dose-dependent manner. Although the effect was variously expressed, there was a statistically significant difference between the MTT absorbance of cells incubated in the presence or absence of the factor. Conditioned medium of each cell line tested showed significantly less adhesion effect than that produced by PC-1.0 cells. Because our previous study indicated that the adhesion factor produced by PC-1.0 cells differed from known growth factors and adhesion molecules including fibronectin, vibronectin, laminin, and collagen, it appears that PC-1.0 cells produce a novel adhesion factor that enhances adherence of normal and malignant cells of different species.