HIGH NM23-H1 NDPK-A EXPRESSION IN EWING TUMORS - PARADOXICAL IMMUNOHISTOCHEMICAL REACTIVITY AND LACK OF PROGNOSTIC-SIGNIFICANCE/

Expression of nm23-HI/NDPK-A has been reported to correlate inversely with metastasizing potential of rodent experimental cells and some hum an tumors. In the search for reliable molecular prognostic indicators for Ewing tumors (ET), a group of aggressive presumably neuroectoderma l malignancies in children and adolescents, we studied nm23-HI/NDPK-A expression. Northern-blot and RT-PCR analyses were employed to semi-qu antificatively measure nm23-HI mRNA levels in ET cell lines and tissue extracts. A panel of monoclonal antibodies (MAbs) were used to evalua te protein abundance by Western blotting and immunohistochemistry. The nm23-HI/NDPK-A gene was also investigated on the DNA level to define possible genomic alterations. Our results revealed neither nm23-HI all elic loss nor gene amplification and failed to show any significant va riation in nm23-HI mRNA or NDPK-A protein levels of primary or metasta tic ET. NDPK-A protein levels were high and comparable to those of MCF -7 breast-cancer cells and to aggressive stage-IV neuroblastoma cell l ines. nm23-H2/NDPK-B expression in ET was slightly more variable but g enerally lower than in MCF-7 cells. In the immunohistochemical analysi s, however, discrepancies in the reactivity patterns with different an tibodies were observed. Differential sensitivity to various fixation m ethods and heat treatment painted to a structurally polymorphic NDPK-A protein. nm23-HI expression studies using immunohistochemistry for pr ognostic counselling should thus be interpreted with caution. (C) 1995 Wiley-Liss, Inc.