Other Applications of Active Endosialidase

In adult rat brain NCAM is not the only polysialylated molecule. The sodium channel glycoprotein has been reported to be polysialylated in its a subunit [59]. The significance of the negative charge on the sodium channel is not clear, but desialylation decreases the conductivity of the channel. a2,8-linked polysialic acid chains are also carried by sodium channels on the electrical organ of the eel Electrophorus electricus [184]. 

Immunohistochemical studies relate polysialic acid-NCAM expression to tumor malignancy in neuroblastoma, alveolar rhabdomyosarcoma [189], neuroendocrine lung tumors [190], Wilm s tumor [191], aggressive colon cancers [192], and pancreatic cancer [193]. In studies on the role of polysialic acid in tumor cell behavior, endosialidase has been used as a tool to remove polysialic acid from the surface of cells and tumors. In a metastasis model using human rhabdomyosarcoma TE671 cells, endoNA injected intraperitoneally reduces the expression of polysialic acid and the number of lung and liver metastases formed from intraperi-toneal primary tumors [194]. For comparison, the effect was not seen with intramuscular primary tumors that cannot be reached by the intraperitoneally injected endosialidase. 

Endosialidase is also of interest as therapeutic agent. For instance, it has been described as an efficient agent in the treatment of septicemia and meiungitis in E. coli K1 infected rats [195]. Small quantities of recombinant endoNE injected intraperitoneally into newborn mouse pups to remove polysialic acid from the bacterial surface are able to prevent the development of bacteremia and death in an experimental 

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