globotriaosylceramide and Liver-Neoplasms

Shiga toxins (Stxs) are composed of an enzymatically active A subunit (StxA) and a pentameric B subunit (StxB) that preferentially binds to the glycosphingolipid (GSL) globo\\xadtriaosylceramide (Gb3Cer/CD77) and to a reduced extent to globotetraosylceramide (Gb4Cer). The identification of Gb3Cer as a tumor-associated GSL in human pancreatic cancer prompted us to investigate the expression of Gb3Cer and Gb4Cer in 15 human pancreatic ductal adenocarcinoma cell lines derived from primary tumors and liver, ascites, and lymph node metastases. Thin-layer chromatography overlay assays revealed the occurrence of Gb3Cer in all and of Gb4Cer in the majority of cell lines, which largely correlated with transcriptional expression analysis of Gb3Cer and Gb4Cer synthases. Prominent Gb3Cer and Gb4Cer lipoform heterogeneity was based on ceramides carrying predominantly C16:0 and C24:0/C24:1 fatty acids. Stx2-mediated cell injury ranged from extremely high sensitivity (CD(50) of 0.94 pg/ml) to high refractiveness (CD(50) of 5.8 μg/ml) and to virtual resistance portrayed by non-determinable CD(50) values even at the highest Stx2 concentration (10 μg/ml) applied. Importantly, Stx2-mediated cytotoxicity did not correlate with Gb3Cer expression (the preferential Stx receptor), suggesting that the GSL receptor content does not primarily determine cell sensitivity and that other, yet to be delineated, cellular factors might influence the responsiveness of cancer cells.

Topics: Adenocarcinoma; Ascites; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Survival; Gene Expression Regulation, Neoplastic; Globosides; Humans; Liver Neoplasms; Lymph Nodes; Shiga Toxin 2; Shiga-Toxigenic Escherichia coli; Trihexosylceramides

The targeting of solid tumors requires delivery tools that resist intracellular and extracellular inactivation, and that are taken up specifically by tumor cells. We have shown previously that the recombinant nontoxic B-subunit of Shiga toxin (STxB) can serve as a delivery tool to target digestive tumors in animal models. The aim of this study was to expand these experiments to human colorectal cancer. Tissue samples of normal colon, benign adenomas, colorectal carcinomas, and liver metastases from 111 patients were obtained for the quantification of the expression of the cellular STxB receptor, the glycosphingolipid globotriaosyl ceramide (Gb(3) or CD77). We found that compared with normal tissue, the expression of Gb(3) was strongly increased in colorectal adenocarcinomas and their metastases, but not in benign adenomas. Short-term primary cultures were prepared from samples of 43 patients, and STxB uptake was studied by immunofluorescence microscopy. Of a given tumor sample, on average, 80% of the cells could visibly bind STxB, and upon incubation at 37 degrees C, STxB was transported to the Golgi apparatus, following the retrograde route. This STxB-specific intracellular targeting allows the molecule to avoid recycling and degradation, and STxB could consequently be detected on tumor cells even 5 days after initial uptake. In conclusion, the targeting properties of STxB could be diverted for the delivery of contrast agents to human colorectal tumors and their metastases, whose early detection and specific targeting remains one of the principal challenges in oncology.

Topics: Adult; Aged; Aged, 80 and over; Antigens, Tumor-Associated, Carbohydrate; Chromatography, Thin Layer; Colorectal Neoplasms; Female; Humans; Intestines; Liver Neoplasms; Male; Middle Aged; Shiga Toxins; Trihexosylceramides

Analysis of the glycosphingolipid composition in one case of uterine leiomyosarcoma metastasized to the liver showed an accumulation of globotriaosylceramide as compared with normal liver and uterus from which the tumour originated. The structure and the amount of glycosphingolipids were established by using specific glycosidases, permethylation analysis and h.p.l.c. The reason for the accumulation of globotriaosylceramide in leiomyosarcoma remains to be answered.

Topics: Chromatography, High Pressure Liquid; Female; Globosides; Glycosphingolipids; Humans; In Vitro Techniques; Leiomyosarcoma; Liver; Liver Neoplasms; Middle Aged; Trihexosylceramides; Uterine Neoplasms; Uterus