Johnston J M, Carroll W L
Department of Pediatrics, University of Utah, Salt Lake City 84112.
Leuk Lymphoma. 1992 Dec;8(6):431-9. doi: 10.3109/10428199209051025.
Translocation between the c-myc protooncogene and one of the three immunoglobulin loci is a cytogenetic hallmark of the B cell tumor, Burkitt's lymphoma. The resulting deregulation of c-myc expression is a critical step in tumorigenesis. The translocation breakpoint may lie within c-myc proper, in which case deregulation is due, in part, to dissociation of key 5' regulatory sequences from the protein-coding portions of the gene. Alternatively, the breakpoint may flank c-myc, leaving the gene grossly intact. In these latter cases, mutation, which may be extensive, is usually seen within c-myc, specifically at or near the same key regulatory sequences. The precise contribution of these mutations to c-myc deregulation is gradually being clarified. The mechanisms underlying c-myc mutations are not known. Hypermutation in c-myc may reflect the influence of the juxtaposed immunoglobulin gene, which is subject to hypermutation during an intermediate stage of normal B lymphoid development. This relationship, however, has not been firmly established.
c-myc原癌基因与三个免疫球蛋白基因座之一之间的易位是B细胞肿瘤——伯基特淋巴瘤的细胞遗传学特征。由此导致的c-myc表达失调是肿瘤发生的关键步骤。易位断点可能位于c-myc本身内部，在这种情况下，失调部分是由于关键的5'调控序列与基因的蛋白质编码部分解离。或者，断点可能位于c-myc侧翼，使基因大体完整。在这些后一种情况下，通常会在c-myc内，特别是在相同的关键调控序列处或其附近，出现可能广泛的突变。这些突变对c-myc失调的确切作用正在逐渐阐明。c-myc突变的潜在机制尚不清楚。c-myc中的高突变可能反映了并列的免疫球蛋白基因的影响，该基因在正常B淋巴细胞发育的中间阶段会发生高突变。然而，这种关系尚未得到确凿证实。
