Reevaluation of the 22-1-1 antibody and its putative antigen, EBAG9-RCAS1, as a tumor markerReportar como inadecuado

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BMC Cancer

, 5:47

First Online: 17 May 2005Received: 18 November 2004Accepted: 17 May 2005DOI: 10.1186-1471-2407-5-47

Cite this article as: Reimer, T.A., Anagnostopoulos, I., Erdmann, B. et al. BMC Cancer 2005 5: 47. doi:10.1186-1471-2407-5-47


BackgroundTumor-associated antigens are appreciated as diagnostic markers, but they have also prompted tremendous efforts to develop tumor-specific immunotherapy. A previously cloned tumor-associated antigen, EBAG9, was initially defined by reactivity with the monoclonal antibody 22-1-1. Functionally, the EBAG9-encoded gene-product was believed to induce apoptosis in activated immune cells. However, using a cell-biological approach we identified EBAG9 as a Golgi-resident modulator of O-linked glycan expression, the latter product was then recognized by the 22-1-1 antibody. Secondly, EBAG9 expression was found physiologically in all murine tissues examined. This raised the question if EBAG9 is tumor-specific and mediates apoptosis itself or through O-linked glycans generated, among them the cognate 22-1-1 antigen Tn.

MethodsWe have used immunohistochemistry to detect the expression of 22-1-1 and EBAG9 in various tissues. Correlation between expression of both antigens in cell lines was analysed by immunoblot and flow cytometry. Apoptosis was studied by using flow cytometry and Caspase-Glo™ 3-7 assay kit. Cellular distribution of EBAG9 was analysed by electron and confocal microscopy.

ResultsHere, we compared expression of the 22-1-1 and EBAG9-defined antigens in normal and neoplastic tissues in situ. In contrast to 22-1-1 staining, EBAG9 is a ubiquitously expressed antigen in all normal and cancerous tissues. Functional studies on the role of 22-1-1 reactive material did not support any evidence for apoptosis induction. Employing electron and confocal microscopy, a refined subcellular localization of EBAG9 at the Golgi was obtained.

ConclusionWe suggest that the estrogen-inducible EBAG9 gene-product and the 22-1-1 defined antigen are structurally and functionally separate antigens.

List of abbreviationsEBAG9estrogen receptor-binding fragment -associated gene 9

RCAS1receptor binding cancer antigen expressed on SiSo cells

BFABrefeldin A


Electronic supplementary materialThe online version of this article doi:10.1186-1471-2407-5-47 contains supplementary material, which is available to authorized users.

Autor: Tatiana A Reimer - Ioannis Anagnostopoulos - Bettina Erdmann - Insa Lehmann - Harald Stein - Peter Daniel - Bernd Dörken


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