Agelopoulos K, Schmidt H, Korsching E, Buerger H, Brandt B
Gerhard Domagk Institut für Pathologie, Universitätsklinikum Münster, Domagkstr. 17, 48149 Münster.
Pathologe. 2008 Nov;29 Suppl 2:333-7. doi: 10.1007/s00292-008-1021-3.
Intratumor genetic heterogeneity, a well-known characteristic of numerous cancers, often confounds a precise diagnosis and leads to therapy resistance. This study deals with such chromosomal variability, which may be due to an inherent genetic instability affecting heterogeneity and clonal effects. Subpopulations of the breast cancer cell line MDA-MB-468 were isolated according to epidermal growth factor receptor (EGFR) expression by FACS. Whole genome profiling (CGH; mapping arrays) and determination of egfr gene amplification (fluorescence in situ hybridisation, FISH; qPCR) were done directly after sorting or after several passages of cell culture. Subpopulations differed in the amplification of the egfr-locus 7p11-14 showing egfr gene amplification rates of up to 60-fold in high-level expressing populations and less than 2-fold in low-level expressing populations. However, after several passages the original low-level cells showed a new amplification of the egfr gene, which was as heterogeneous as the original amplification detected in MDA-MB-468. Additional, spontaneously expressed fragile sites could be shown in FISH analyses which may affect cell culture heterogeneity. Understanding the precise chromosomal process would clarify mechanisms in vivo and improve both diagnosis and therapy of corresponding cancers.
肿瘤内基因异质性是众多癌症的一个众所周知的特征，常常使精确诊断变得复杂并导致治疗抗性。本研究探讨了这种染色体变异性，其可能归因于影响异质性和克隆效应的内在基因不稳定性。通过荧光激活细胞分选术（FACS）根据表皮生长因子受体（EGFR）表达分离乳腺癌细胞系MDA-MB-468的亚群。分选后或细胞培养几代后直接进行全基因组分析（比较基因组杂交；图谱阵列）以及egfr基因扩增的测定（荧光原位杂交，FISH；定量聚合酶链反应，qPCR）。亚群在egfr基因座7p11-14的扩增方面存在差异，在高表达群体中egfr基因扩增率高达60倍，而在低表达群体中小于2倍。然而，几代后原来的低表达细胞显示出egfr基因的新扩增，其与在MDA-MB-468中检测到的原始扩增一样具有异质性。此外，在FISH分析中可显示出额外的自发表达的脆性位点，其可能影响细胞培养的异质性。了解精确的染色体过程将阐明体内机制并改善相应癌症的诊断和治疗。
