Mostert M M, van de Pol M, van Echten J, Olde Weghuis D, Geurts van Kessel A, Oosterhuis J W, Looijenga L H
Laboratory for Experimental Patho-Oncology Dr. Daniel den Hoed Cancer Center, University Hospital Rotterdam, The Netherlands.
Cancer Genet Cytogenet. 1996 Apr;87(2):95-102. doi: 10.1016/0165-4608(95)00233-2.
Overrepresentation of the short arm of chromosome 12 is frequently detected in human testicular germ cell tumors of adolescents and adults (TGCT). This overrepresentation mostly results from the formation of an isochromosome: i(12p). Whether the overrepresentation consistently involves the complete 12p arm including the centromere is still unclear. We studied five TGCT-derived cell lines (NT2, 2102Ep, H12.1, NCCIT, and S2), combining conventional chromosome banding, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH) to investigate the suitability of each of these techniques to detect aberrations involving chromosome 12. Karyotyping showed one or more i(12p)s in NT2, 2102Ep, H12.1, and S2. However, FISH with a centromere-specific probe (p alpha 12H8), a 12p "paint" and a 12p11.2--p12.1 region-specific probe yeast artificial chromosome (YAC)#5 and CGH could not confirm the presence of an i(12p) in S2. Additional randomly distributed 12p sequences were detected by FISH in H12.1, NCCIT, and S2. In most of these cases, (a part of) the centromere was included. All overrepresented 12p regions, except for those in S2, showed hybridization with YAC#5. CGH showed increased copy numbers of the complete 12p arm in the cell lines with one or more i(12p)s but no overrepresentation was noted in the cell lines without i(12p). In metaphase spreads, the centromeric block of the i(12p)s differed in size as compared with those of normal chromosomes 12. This was rarely noted in interphase nuclei. A decrease in size of the centromeric block in 2102Ep and H12.1 caused a weak FISH signal, which was difficult to detect, especially in interphase nuclei. The ratio between p alpha 12H8- and YAC#5-derived signals reflected the presence or absence of one or more i(12p)s. Our results indicate that double FISH with a centromere- and a 12p-specific probe can be used to detect 12p overrepresentation [including i(12p)] in TGCT both in metaphase spreads and interphase nuclei. CGH confirmed the relative overrepresentation of 12p sequences as detected by FISH and showed that in these cell lines the complete 12p was involved.
在青少年和成人的睾丸生殖细胞肿瘤（TGCT）中，经常检测到12号染色体短臂的过度代表。这种过度代表主要是由于等臂染色体i(12p)的形成。目前尚不清楚这种过度代表是否始终涉及包括着丝粒在内的完整12p臂。我们研究了五种TGCT衍生的细胞系（NT2、2102Ep、H12.1、NCCIT和S2），结合传统染色体显带、荧光原位杂交（FISH）和比较基因组杂交（CGH），以研究这些技术检测涉及12号染色体畸变的适用性。核型分析显示NT2、2102Ep、H12.1和S2中有一个或多个i(12p)。然而，使用着丝粒特异性探针（p alpha 12H8）、12p“探针”和12p11.2 - p12.1区域特异性探针酵母人工染色体（YAC）#5进行的FISH以及CGH均无法证实S2中存在i(12p)。FISH在H12.1、NCCIT和S2中检测到了额外随机分布的12p序列。在大多数情况下，（部分）着丝粒也包含在内。除了S2中的那些区域外，所有过度代表的12p区域均与YAC#5杂交。CGH显示，具有一个或多个i(12p)的细胞系中完整12p臂的拷贝数增加，但在没有i(12p)的细胞系中未发现过度代表。在中期染色体铺展中，i(12p)的着丝粒块与正常12号染色体的着丝粒块大小不同。在间期核中很少观察到这种情况。2102Ep和H12.1中着丝粒块大小的减小导致FISH信号较弱，难以检测到，尤其是在间期核中。p alpha 12H8和YAC#5衍生信号的比值反映了一个或多个i(12p)的存在与否。我们的结果表明，使用着丝粒和12p特异性探针进行双重FISH可用于在中期染色体铺展和间期核中检测TGCT中12p的过度代表[包括i(12p)]。CGH证实了FISH检测到的12p序列的相对过度代表，并表明在这些细胞系中完整的12p均被涉及。
