Correlation of amplification and overexpression of the c-myc oncogene in high-grade breast cancer: FISH, in situ hybridisation and immunohistochemical analyses.
Correlation of amplification and overexpression of the c-myc oncogene in high-grade breast cancer: FISH, in situ hybridisation and immunohistochemical analyses.
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DOI：
10.1038/sj.bjc.6601703
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发表时间：
2004-04-19
影响因子：
8.8
通讯作者：
Dickson, R B
中科院分区：
文献类型：
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作者：
Blancato, J;Singh, B;Liu, A;Liao, D J;Dickson, R B
本研究采用荧光原位杂交(FISH)、非放射性原位杂交和免疫组织化学方法，对高级别乳腺癌档案组织标本中c-myc基因的扩增、RNA表达和蛋白表达进行了分析。我们解决的具体问题是c-Myc mRNA和蛋白的表达是否与其基因复制扩增有关，如FISH所确定的那样。虽然c-Myc是人类乳腺癌中最常见的扩增癌基因之一，但很少有研究利用原位方法直接分析人类乳腺癌组织切片上的基因复制扩增、RNA转录和蛋白表达。我们现在报道，通过使用敏感的FISH技术，高比例(70%)的高级别乳腺癌被扩增出c-myc基因，而与雌激素受体的状态无关。然而，扩增水平很低，基因扩增只有一到四个拷贝，大多数(84%)的这种基因扩增只获得了一到两个拷贝。大约92%的病例c-myc RNA转录阳性，基本上都有c-myc蛋白表达。事实上，检测到了广泛的表达水平。基因扩增指数、RNA表达得分和蛋白质表达得分之间存在显著的统计学相关性。FISH检测c-myc基因扩增与其在侵袭性细胞中的原位杂交强度(P=0.0067)和侵袭性细胞表达阳性百分率(P=0.0006)显著相关。C-myc基因扩增与侵袭细胞中高表达c-myc蛋白的肿瘤细胞百分率呈正相关(P=0.0016)。因此，尽管已知多种机制调节c-myc的正常和异常表达，但在本研究中，使用原位方法评估高级别人类乳腺癌，c-myc的基因扩增似乎在调节其mRNA和蛋白的表达方面发挥关键作用。
In this study, we analysed gene amplification, RNA expression and protein expression of the c-myc gene on archival tissue specimens of high-grade human breast cancer, using fluorescent in situ hybridisation (FISH), nonradioactive in situ hybridisation and immunohistochemistry. The specific question that we addressed was whether expression of c-Myc mRNA and protein were correlated with its gene copy amplification, as determined by FISH. Although c-Myc is one of the most commonly amplified oncogenes in human breast cancer, few studies have utilised in situ approaches to directly analyse the gene copy amplification, RNA transcription and protein expression on human breast tumour tissue sections. We now report that by using the sensitive FISH technique, a high proportion (70%) of high-grade breast carcinoma were amplified for the c-myc gene, irrespective of status of the oestrogen receptor. However, the level of amplification was low, ranging between one and four copies of gene gains, and the majority (84%) of the cases with this gene amplification gained only one to two copies. Approximately 92% of the cases were positive for c-myc RNA transcription, and essentially all demonstrated c-myc protein expression. In fact, a wide range of expression levels were detected. Statistically significant correlations were identified among the gene amplification indices, the RNA expression scores and protein expression scores. c-myc gene amplification, as detected by FISH, was significantly associated with expression of its mRNA, as measured by the intensity of in situ hybridisation in invasive cells (P=0.0067), and by the percentage of invasive cells positive for mRNA expression (P=0.0006). c-myc gene amplification was also correlated with the percentage of tumour cells which expressed high levels of its protein, as detected by immunohistochemistry in invasive cells (P=0.0016). Thus, although multiple mechanisms are known to regulate normal and aberrent expression of c-myc, in this study, where in situ methodologies were used to evaluate high-grade human breast cancers, gene amplification of c-myc appears to play a key role in regulating expression of its mRNA and protein.