Human colorectal tumors and metastases express Gb3 and can be targeted by an intestinal pathogen-based delivery tool

Abstract

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°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. [Mol Cancer Ther 2008;7(8):2498 -508]

Gastric Adenocarcinomas Express the Glycosphingolipid Gb3/CD77: Targeting of Gastric Cancer Cells with Shiga Toxin B-Subunit

“…The nontoxic B-subunit of the bacterial Shiga toxin (STxB) may be used as an efficient and specific tool for tumor targeting. The cellular STxB receptor, the neutral glycosphingolipid globotriaosylceramide Gb 3 (Gala1-4Galb1-4Glcb1-1Cer), or CD77, is overexpressed in colon carcinoma (6,21), pancreatic (5,8), and breast cancer (25). Moreover, STxB can be functionalized and coupled to specific agents for noninvasive or endoscopic tumor imaging, which has successfully been demonstrated in preclinical models (28,36).…”

“…Cellular morphology and growth characteristics were analyzed regularly, and no phenotype changes were observed through the study. STxB-Cy3, or BSA-Cy3 as control, was added at final concentration of 2.5 mg/mL as published earlier (6).…”

“…[4][5][6][7][8]. The terminal disaccharide of this lipid is the receptor of the bacterial Shiga toxin.…”

“…The decisive requirement for application of STxB is the cellspecific expression of Gb 3 in tumor cells: Gb3 is expressed by Burkitt and centrofollicular lymphoma and solid tumors like testicular seminoma, breast, ovary, pancreatic, and colon cancer (5,6,8,(19)(20)(21)(22)(23)(24)(25)(26).…”

The effects of the carboxyl-terminus amino acids of the Shiga toxin B-subunit on retrograde transport

“…Gb3 is overexpressed in many human cancers, such as breast cancer, colon carcinoma and lymphoma (28). The STxB retrograde transport pathway has been applied as a delivery tool for chemotherapy against cancer (13,29).…”