title: The systemic administration of lethal toxin achieves a growth delay of human melanoma and neuroblastoma xenografts: assessment of receptor contribution.
abstract: Two of the three components of anthrax toxin, protective antigen (PA) and lethal factor (LF), together known as lethal toxin (LeTx), reportedly show anti-tumor activity in melanoma in vitro and in vivo. The growth inhibitory activity of LeTx in culture was determined in nine human cancer cell lines, including melanoma, neuroblastoma and adenocarcinoma cells, as well as in human umbilical vein endothelial cells (HUVEC). The contribution of the two known PA receptor proteins, ANTXR1/TEM8 and ANTXR2/CMG2, to the sensitivity of the cells was assessed. The efficacy of LeTx was evaluated in vivo in the SK-N-AS neuroblastoma and SK-MEL-28 melanoma tumor xenograft models. Sensitivity to LeTx in vitro was observed in the neuroblastoma and colorectal adenocarcinoma cells and HUVEC, as well as melanoma cells. ANTXR1/TEM8 and ANTXR2/CMG2 protein expression studies suggested that a certain threshold of the PA receptor protein level must be met for sensitivity to LeTx to be observed. However, although the SK-N-AS neuroblastoma cells expressed the highest levels of receptor proteins and achieved the lowest IC50 in vitro (0.1 ng/ml), we observed no correlation between either the ANTXR1/TEM8 or ANTXR2/CMG2 protein levels and sensitivity to LeTx in vitro. In vivo, LeTx was an active anti-tumor agent when administered intravenously to mice bearing the human SK-N-AS or SK-MEL-28 tumor xenografts. The tumor growth delays were 6-8 days with a lower dose regimen and 14-16 days with a higher dose regimen for the two tumor models. These in vitro data suggest that LeTx may have broad therapeutic indications in cancer and the in vivo studies demonstrate that LeTx has systemic efficacy in neuroblastoma as well as melanoma. The therapeutic potential of LeTx needs to be further investigated in non-melanoma tumor models expressing the ANTXR1/TEM8 and/or ANTXR2/CMG2 protein.
authors: Genzyme Corporation, Framingham, MA 01701, USA. cecile.rouleau@genzyme.com
authors: Cecile
authors: C
authors: Rouleau
authors: Krishna
authors: K
authors: Menon
authors: Paula
authors: P
authors: Boutin
authors: Cheryl
authors: C
authors: Guyre
authors: Hitoshi
authors: H
authors: Yoshida
authors: Shiro
authors: S
authors: Kataoka
authors: Michael
authors: M
authors: Perricone
authors: Srinivas
authors: S
authors: Shankara
authors: Arthur E
authors: AE
authors: Frankel
authors: Nicholas S
authors: NS
authors: Duesbery
authors: George
authors: G
authors: Vande Woude
authors: Hans-Peter
authors: HP
authors: Biemann
authors: Beverly A
authors: BA
authors: Teicher
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000627:therapeutic use*; D001427:Bacterial Toxins / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D009447:Neuroblastoma / Q000188:drug therapy* / Q000473:pathology; D018000:Receptors, Peptide / Q000032:analysis*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D018000:Receptors, Peptide; C030325:anthrax toxin; C070309:anthrax toxin receptors