Glycolipid-bound sialic acid in serum: increased levels in mice and humans bearing mammary carcinomas.

Abstract

In mice bearing transplantable mammary carcinomas, serum levels of sialic acid-containing glycolipids were elevated 2.5-fold in pooled serum samples from which gangliosides were purified by column chromatography. A method is also described by which ganglioside content was estimated on as little as 1.0 ml of whole blood to permit studies with individual tumor-bearing mice and age-and litter-matched controls. Using this method, we observed similar elevations in ganglioside levels that were independent of age and sex of the animal and appeared in advance of palpable tumors. Following excision of the tumors, the glycolipid sialic acid values dropped below control levels and remained there. Serum sialic acid of the glycolipid fraction was elevated nearly 2-fold in human carcinoma patients and appeared to decline after surgery. taneous implantation of tumor fragments into male or female syngeneic recipients. Age-matched controls of the same strain were injected with an equivalent amount of saline but received no tumor implant and were otherwise treated exactly as the principals. Tumor masses were examined for degree of vascularization and then were excised and weighed. Determination of Gangliosides. Groups of 25 carcinomabearing mice were exsanguinated 60 days after implantation of tumor fragments. Sera were pooled following centrifugation. Gangliosides were extracted with chloroform/methanol and further purified by chromatography on DEAE-Sephadex and Unisil silicic acid (16). Sialic acid assays (17) were on purified gangliosides. By this method recovery of [6-3H]galactose-Nacetylgalactosamine-(N-acetylneuraminic acid)-galactoseglucose-ceramide ([3H]GM1) added to samples averaged 96%.Individual mice bearing tumors were exsanguinated at 3-90 days after implantation of tumors along with litter-matched control mice as described above. The sera (0.5-1 ml) obtained following centrifugation were extracted with chloroform/ methanol (1:1 vol/vol) overnight. The extracts were filtered and the residue was extracted a second time with chloroform/ methanol (2:1) overnight. The combined extracts were concentrated and adjusted to 3 ml. To precipitate sialic acid-containing lipo-and glycoproteins (not elevated in sera of tumor bearers), 100 ,ul of a 0.1% solution of tripotassium citrate (18) was added and the resulting precipitate was removed by centrifugation. The supernatant after citrate treatment was analyzed for sialic acid (17) using values calculated by the Warren (17) formula to correct for variation due to unspecific absorbance. With this method recovery of [3H]GM1 added to serum samples averaged 92%. RESULTS Animal modelThe level of total gangliosides, determined on the basis of sialic acid, was elevated about 2.5 times above control values in sera of both male and female recipient mice carrying a transplantable mammary carcinoma of spontaneous origin (Table 1). Similar elevations were observed at 11, 21, and 35 days after transplantation; at 11 days palpable tumor masses were not detected. These increases were no...

Detection of a Tumour-Associated Ganglioside in Plasma of Patients With Neuroblastoma

“…An association between abnormalities in circulating gangliosides and the presence of tumour is suggested by the knowledge that membrane-bound gangliosides are, among other molecules on the cell surface, released by proliferating cells. 1,2 Findings of high concentrations of gangliosides in the circulation of tumour-bearing hosts, [3][4][5][6][7] which fall towards normal on removal of tumour, 4,5 support this association, as does the indirect evidence that binding between a monoclonal antibody and a colon-carcinoma-associated ganglioside is inhibited by the serum of patients with this tumour. 14 To date, however, direct thin-layer-chromatographic visualisation of gangliosides isolated and purified from the plasma of patients with cancer has not shown the presence of any ganglioside which was not also detected though perhaps in lower concentrations in the plasma of healthy normal donors.…”

“…These membrane-bound glycolipids are released or shed in vitro by many cells, especially proliferating cells such as tumour cells. 1,2 It has been suggested that high concentrations of gangliosides, present in the circulation of tumour-bearing hosts, [3][4][5][6][7] may be tumour-related. 4 To date, however, there has been no report of direct visualisation and identification of a ganglioside in the plasma of patients with cancer that has not also been detected in normal plasma.…”

Immune Response Modulation by Tumor-Secreted Glycosphingolipids

“…The idea that tumors might shed GSL into the extracellular space dates back to an observation nearly 40 years ago in breast cancer patients who had elevated serum levels of sialic acid-containing GSL [71]. Portoukalian et al later found that the same GSL shed by melanomas were also enriched in erythrocyte plasma membranes of melanoma patients [72].…”

Potential Use of Specific Human and Chicken Antibodies for Detection of Hanganutziu-Deicher Antigen (S) in Sera of Cancer Patients

“…Cancer patients are known to possess HD antibodies (15,16). Compared to normal human sera, those of cancer patients are reported to have higher levels of lipid-bound sialic acid (17,18). With this understanding, this study was undertaken to evaluate the use of the RIA system which is capable of detecting an HD antigen-active ganglioside or a glycoprotein in tissues and sera.…”