ACTIVATION OF MYCN IN A CASE OF NON-HODGKINS-LYMPHOMA

We have examined a series of non-Hodgkin's lymphomas (NHL) for evidenc e of expression of the MYC gene family. Northern blot analysis of RNA samples derived from 11 non-malignant reactive lymphoid tissues and 33 NHL was used to investigate expression of MYC, MYCL and MYCN. As expe cted MYC expression was detected in all samples. The levels of MYC exp ression were quantified by densitometry and appeared to be 3-8 fold hi gher in high grade NHL than in the low grade NHL or non-malignant lymp hoid tissue. No expression of MYCL was detected in any sample. Express ion of MYCN was however observed in one sample, which had been diagnos ed as a T-cell high grade NHL. A detailed cytogenetic analysis of this sample proved difficult to obtain but, by using fluorescence in-situ hybridization (FISH), we were able to demonstrate that on one of the c hromosomes 2 the MYCN gene was localised to a translocation breakpoint region. It therefore appears that in NHL it is possible for MYCN, lik e MYC in Burkitt lymphoma, to be activated as a result of a chromosome translocation event.