Pascale R M, De Miglio M R, Muroni M R, Simile M M, Daino L, Seddaiu M A, Nufris A, Gaspa L, Deiana L, Feo F
Istituto di Patologia Generale e Centro di Ricerche Oncologiche dell'Università di Sassari, Italy.
Int J Cancer. 1996 Sep 27;68(1):136-42. doi: 10.1002/(SICI)1097-0215(19960927)68:1<136::AID-IJC24>3.0.CO;2-8.
We have investigated by restriction fragment analysis genomic abnormalities involving the c-myc gene in DNA isolated from adenomas and hepatocellular carcinomas (HCCs). Adenomas and HCCs were induced by the "resistant hepatocyte" protocol in diethylnitrosamine-initiated male F344 rats. Southern-blot analysis of EcoRI-restricted DNA from normal liver, early and late adenomas, 12 weeks (EAs) and 30 weeks (LAs) after initiation, and HCCs, showed 2 bands of 18 and 3.2 kb hybridizing with c-myc, in all tissues. c-myc amplification occurred in almost all HCCs, and in the majority of EAs and LAs. These results were confirmed by dilution analysis. c-myc amplification was also seen in adenomas and HCCs by Southern analysis with HindIII-restricted DNA, and in HCCs by differential PCR. c-myc mRNA increase occurred in all adenomas and HCCs, but it was higher in the lesions showing gene amplification. Moreover, a 13-kb DNA extraband, hybridizing with c-myc, was found in the HindIII-restricted DNA from HCCs, but not in normal liver and adenomas, and a 7.1-kb extra band was present in EcoRI-digested DNA from one LA. EcoRI-restricted DNA from some adenomas exhibited a decrease in intensity of the 18-kb fragment, and an increase in intensity of the 3.2-kb fragment. No alteration in banding pattern occurred in the beta-actin gene in adenomas. These results provide evidence of amplification and some other rearrangements involving the c-myc gene, in pre-malignant and malignant liver lesions, induced by the RH protocol, and suggest a role of c-myc rearrangement in the progression of adenomas to malignancy.
我们通过限制性片段分析，研究了从腺瘤和肝细胞癌（HCC）中分离出的DNA中涉及c-myc基因的基因组异常情况。腺瘤和HCC是通过“抗性肝细胞”方案在经二乙基亚硝胺启动的雄性F344大鼠中诱导产生的。对正常肝脏、早期和晚期腺瘤（启动后12周的早期腺瘤（EA）和30周的晚期腺瘤（LA））以及HCC的EcoRI限制性DNA进行Southern印迹分析，结果显示在所有组织中均有两条与c-myc杂交的条带，大小分别为18 kb和3.2 kb。几乎所有的HCC以及大多数EA和LA中都发生了c-myc基因扩增。这些结果通过稀释分析得到了证实。用HindIII限制性DNA进行Southern分析，在腺瘤和HCC中也观察到了c-myc基因扩增，通过差异PCR在HCC中也观察到了该扩增。在所有腺瘤和HCC中均出现了c-myc mRNA增加的情况，但在显示基因扩增的病变中增加得更高。此外，在HCC的HindIII限制性DNA中发现了一条与c-myc杂交的13 kb额外条带，但在正常肝脏和腺瘤中未发现，在一个LA的EcoRI消化DNA中存在一条7.1 kb的额外条带。一些腺瘤的EcoRI限制性DNA显示18 kb片段的强度降低，3.2 kb片段的强度增加。腺瘤中β-肌动蛋白基因的条带模式没有改变。这些结果提供了证据，表明在由RH方案诱导的癌前和恶性肝脏病变中，存在涉及c-myc基因的扩增和其他一些重排情况，并提示c-myc重排在腺瘤向恶性肿瘤进展过程中发挥作用。
