title: Human breast cancer and lymph node metastases express Gb3 and can be targeted by STxB-vectorized chemotherapeutic compounds.
abstract: BACKGROUND
  The B-subunit of Shiga toxin (STxB) specifically binds to the glycosphingolipid Gb3 that is highly expressed on a number of human tumors and has been shown to target tumor cells in mouse models and ex vivo on primary colon carcinoma specimen.
  
  
  METHODS
  Using a novel ex vivo STxB labeling (ESL) method we studied Gb3 expression in cytological specimens of primary human breast tumors from 107 patients, and in synchronous lymph node metastases from 20 patients. Fluorescent STxB was incubated with fine-needle aspiration (FNA) specimens, and Gb3 expression was evaluated by fluorescence microscopy. Furthermore, 11 patient-derived human breast cancer xenografts (HBCx) were evaluated for expression of Gb3 by ESL and FACS. In addition, the biodistribution of fluorescent STxB conjugate was studied after intravenous injection in a Gb3 positive HBCx model.
  
  
  RESULTS
  Gb3 expression was detected in 62 of 107 patients (57.9%), mainly in epithelial tumor cells. Gb3 positivity correlated with estrogen receptor expression (p≤0.01), whereas absence of Gb3 expression in primary tumors was correlated with the presence of lymph node metastases (p≤0.03). 65% of lymph node metastases were Gb3 positive and in 40% of tested patients, we observed a statistically significant increase of metastatic Gb3 expression (p≤0.04). Using concordant ESL and flow cytometry analysis, 6 out of 11 HBCx samples were scored positive. Intravenous injections of fluorescent STxB into HBC xenografted mice showed preferential STxB accumulation in epithelial cells and cells with endothelial morphology of the tumor.
  
  
  CONCLUSIONS
  The enhanced expression of Gb3 in primary breast carcinomas and its lymph node metastases indicate that the development of STxB-based therapeutic strategies is of interest in this pathology. Gb3 expressing HBCx can be used as a model for preclinical studies with STxB conjugates. Finally, the ESL technique on FNA represents a rapid and cost effective method for the stratification of patients in future clinical trials.
authors.forename: Lev
authors.initials: L
authors.lastname: Stimmer
authors.forename: Sabrina
authors.initials: S
authors.lastname: Dehay
authors.forename: Fariba
authors.initials: F
authors.lastname: Nemati
authors.forename: Gerald
authors.initials: G
authors.lastname: Massonnet
authors.forename: Sophie
authors.initials: S
authors.lastname: Richon
authors.forename: Didier
authors.initials: D
authors.lastname: Decaudin
authors.forename: Jerzy
authors.initials: J
authors.lastname: Klijanienko
authors.affiliation: Endocytic Trafficking and Therapeutic Delivery Group, UMR3666 CNRS - U1143 INSERM, Institut Curie-Centre de Recherche, 26 rue d'Ulm, 75248 Paris Cedex 05, France. ludger.johannes@curie.fr.
authors.forename: Ludger
authors.initials: L
authors.lastname: Johannes
mesh_terms: D000232:Adenofibroma / Q000737:chemistry*; D000818:Animals; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000032:analysis*; D044963:Biopsy, Fine-Needle; D001940:Breast / Q000737:chemistry; D001943:Breast Neoplasms / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology; D002277:Carcinoma / Q000737:chemistry* / Q000378:metabolism / Q000556:secondary; D016503:Drug Delivery Systems; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007275:Injections, Intravenous; D008207:Lymphatic Metastasis; D042361:Mammary Glands, Human / Q000737:chemistry; D051379:Mice; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000032:analysis; D022603:Shiga Toxins / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D015295:Antigens, Tumor-Associated, Carbohydrate; C472766:Gb3 antigen; D011960:Receptors, Estrogen; D022603:Shiga Toxins; C077239:stxB toxin