Kerns B J, Pence J C, Huper G, Kinney R B, Iglehart J D
Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710.
J Histochem Cytochem. 1990 Dec;38(12):1823-30. doi: 10.1177/38.12.1979342.
Evidence that the c-erbB-2 proto-oncogene is important in prognosis and oncogenesis in a number of human malignancies is increasing. DNA (Southern) hybridization and immunoblotting (Western) techniques are most commonly utilized to determine the amplification and protein expression of this proto-oncogene, respectively. These extraction techniques are often time consuming, costly, and subject to variability depending on the histological characteristics of the tumor. Immunohistochemistry (IHC), on the other hand, is more often time and cost effective. In addition, IHC may offer enhanced sensitivity over extraction techniques because of the in situ nature of analysis. In data presented here, 71 cases of human mammary carcinoma were concomitantly assessed for c-erbB-2 gene copy number and oncoprotein expression by dilution DNA hybridization and IHC, respectively. In 65 (92%) of 71 cases, high-level expression was associated with gene amplification, whereas moderate or low-level expression was associated with a normal diploid gene copy number. In five of the six discrepant cases, IHC predicted amplification which was not corroborated by Southern analysis. In these cases, tumor mass was limited by the intraductal component of the lesion or by an abundance of stromal elements within the specimen. In 39 of the 71 total cases, Western immunoblotting was compared with IHC in the assessment of oncoprotein expression. Concordance was found in 33 (85%) of 39 cases. In four of the six discrepant cases, high levels of c-erbB-2 expression were demonstrated by IHC but not by immunoblotting. In these cases, intraductal disease and stroma-rich tumors again led to a relative paucity of neoplastic tissue within the specimens. We conclude that IHC offers a favorable alternative to either Southern analysis or Western immunoblotting in the assessment of c-erbB-2 gene copy number and expression levels of oncoprotein in human mammary carcinoma. Furthermore, IHC may prove advantageous to either extraction technique in specimens with limited tumor mass, such as biopsy materials, stroma-rich tumors, or early stage lesions such as intraductal carcinoma.
越来越多的证据表明，c-erbB-2原癌基因在多种人类恶性肿瘤的预后和肿瘤发生中起着重要作用。DNA（Southern）杂交和免疫印迹（Western）技术最常用于分别确定该原癌基因的扩增和蛋白质表达。这些提取技术通常耗时、成本高，并且根据肿瘤的组织学特征存在变异性。另一方面，免疫组织化学（IHC）通常更节省时间和成本。此外，由于分析的原位性质，免疫组织化学可能比提取技术具有更高的灵敏度。在此呈现的数据中，分别通过稀释DNA杂交和免疫组织化学对71例人类乳腺癌的c-erbB-2基因拷贝数和癌蛋白表达进行了同步评估。在71例中的65例（92%）中，高水平表达与基因扩增相关，而中等或低水平表达与正常二倍体基因拷贝数相关。在6例不一致的病例中的5例中，免疫组织化学预测的扩增未得到Southern分析的证实。在这些病例中，肿瘤块受病变的导管内成分或标本中丰富的基质成分限制。在71例总病例中的39例中，在评估癌蛋白表达时将Western免疫印迹与免疫组织化学进行了比较。在39例中的33例（85%）中发现了一致性。在6例不一致的病例中的4例中，免疫组织化学显示c-erbB-2表达水平高，但免疫印迹未显示。在这些病例中，导管内疾病和富含基质的肿瘤再次导致标本中肿瘤组织相对较少。我们得出结论，在评估人类乳腺癌中c-erbB-2基因拷贝数和癌蛋白表达水平时，免疫组织化学是Southern分析或Western免疫印迹的有利替代方法。此外，对于肿瘤块有限的标本，如活检材料、富含基质的肿瘤或早期病变如导管内癌，免疫组织化学可能比任何一种提取技术都更具优势。
