Molecular biology of 3q27 translocation in lymphoid malignancies

首先，我们研究了BCL6基因3q27带5'部分的结构改变，该部分在B细胞非霍奇金淋巴瘤（B- nhl）患者中经常受到染色体易位的影响。我们发现11例BCL6异常患者中有5例在两个等位基因上都有两个独立的DNA重排，在Southern blotting上呈现多个重排带。此外，其中一项研究发现，在非易位的3号染色体上的BCL6位点产生了1.5kb的内部DNA缺失。我们的研究结果表明，双等位基因重排和亚微观局部重组的发生可能是B-NHL中BCL6异常的独特特征。接下来，我们分析了在两种携带3q27易位的细胞系中识别的BCL6 mRNA的异常表达。对这些细胞的cDNA分析表明，BCL6 mRNA的5'非编码区被免疫球蛋白基因（包括内含子序列）的转录物取代，形成独特的嵌合转录物。

First, we studied the structural alterations within the 5' part of the BCL6 gene on the band 3q27, where is frequently affected by chromosomal translocations in B cell non-Hodgkin's lymphoma (B-NHL) patients. We found that five out of 11 patients with BCL6 abnormality had two independent DNA rearrangements on both alleles, presenting multiple rearranged bands on Southern blotting.Furthermore, in one of them, it was revealed that an internal DNA deletion of 1.5kb area was generated within the BCL6 locus on untranslocated chromosome 3. Our results suggest that the occurrence of biallelic rearrangements and submicroscopic local recombinations would be unique features with BCL6 abnormality in B-NHL.Next, we analyzed aberrant expressions of the BCL6 mRNA recognized in two cell lines harboring 3q27 translocations.Analysis of cDNA from these cells revealed that the 5' non-coding region of the BCL6 mRNA was substituted by transcripts from immunoglobulin genes including intronic sequences, forming unique chimeric transcripts.