APPLICATION OF FLUORESCENCE IN-SITU HYBRIDIZATION TO DETECT N-MYC (MYCN) GENE AMPLIFICATION ON PARAFFIN-EMBEDDED TISSUE-SECTIONS OF NEUROBLASTOMAS

Fluorescence in situ hybridization (FISH) was applied to neuroblastoma for detection of N-myc (MYCN) oncogene amplification, and the results were compared with Southern blot analysis (Southern). In nine neurobl astomas (formalin-fixed paraffin-embedded tissues were available in se ven cases including two cases with touch preparations, and two cell li nes), all five cases with N-myc amplification detected by Southern had cells with multiple N-myc signals by FISH, and three cases showed no N-myc amplification either by Southern or FISH procedure. One case, no t examined by Southern, showed amplified signals of N-myc by FISH. The se data indicate that FISH results for N-myc amplification have close correlation with Southern blot analysis. The chromosome 2-specific rep etitive DNA probe was also applied for the analysis of ploidy by FISH. Six cases with N-myc amplification by Southern and/or FISH had diploi d tumors and two cases without amplified N-myc showed aneuploidy. The remaining one case consisted of heterogeneous elements showing diploid y in undifferentiated tissue and both aneuploidy (ganglionic cells) an d diploidy (Schwann cells) in differentiated area. We conclude that FI SH is a practical, useful and reliable method over Southern especially for analysis of N-myc amplification in neuroblastoma, and simultaneou s cohybridization with a specific chromosome probe is of great Value i n predicting the prognosis of patients. (C) 1997 Wiley-Liss, Inc.