Protein Overexpression and Gene Amplification of c-erbB-2 in Pulmonary Carcinomas: A Comparative Immunohistochemical and Fluorescence In Situ Hybridization Study

Abstract

Amplification of the c-er bB-2 gene (located on 17q11.2-12) is accompanied by overexpression of its cell surface receptor product, p185 ERBB2 . In pulmonary carcinomas, however, there has been disagreement between the reported frequencies of gene amplification and overexpression. To clarify their relationship, the correlation between the cellular expression of p185 ERBB2 and the level of c-erb B-2 gene amplification was studied. A total of 195 pulmonary carcinomas (182 primary and 13 metastatic) were examined immunohistochemically using a polyclonal antibody, which recognizes the internal domain of the human c-erb B-2 protein, and positive tumors were further examined for the gene amplification by dual-color fluorescence in situ hybridization using probes for centromere 17 and 17q11.2-12. By immunohistochemistry, distinct membrane staining was found in an adenocarcinoma, a large cell carcinoma and a metastatic carcinoma from the breast, and cytoplasmic and/or faint membranous staining was observed in 23 nonsmall cell lung carcinomas. It was in the two primaries and the metastatic carcinoma that more than 8-fold amplification of c-erb B-2 was found by fluorescence in situ hybridization. Especially, in the two primary carcinomas, tumor cells had amplified genes with the signals forming one or two clusters, indicating that the amplified gene was present in homogeneously staining regions. Among the 23 tumors, three tumors showed low-level amplification (less than 3-fold), which was differentiated from polysomy 17 found in the other two. In the 30 nonsmall cell lung carcinomas selected at random from 151 with negative immunostaining, there were five trisomy 17, but no tumors with the gene amplification. This suggests that although c-erb B-2 amplification in pulmonary carcinoma is rare, it occurs in the form of a homogeneously staining region and is thought to control the overexpression of the protein in the cell membrane. New adjuvant therapy using a humanized antibody to the oncoprotein may be beneficial to patients with these tumors.

Evaluation of HER-2/neu gene amplification and protein expression in non-small cell lung carcinomas

“…Other studies, such as Hirashima et al (2001) and Cox et al (2001) also detected clustered amplification only in rare cases of NSCLC. Disomic status for chromosome 17 was only found in 16% of the NSCLC tumours included in our study.…”

“…However, because of the strong intensity of the staining pattern, we classified these tumours as having 2+ results (Figure 1). This could give a slightly higher frequency of positive adenocarcinomas compared to other studies (Cox et al, 2001;Hirashima et al, 2001). However, the clinical significance of this scoring may not be relevant because 2+ tumours do not have a worse prognosis and may not have a significant benefit from HER-2/neu targeted therapy.…”

Correlation between encoded protein overexpression and copy number of the HER2 gene with survival in non‐small cell lung cancer

“…They further analyzed the 21 IHCpositive cases identified by FISH and reported that 3ϩ tumors possessed gene amplification but not 2ϩ or 1ϩ tumors, except 1 case of polyploidy. Hirashima et al 26 analyzed the copy number of the HER2 gene by FISH in 25 IHC-positive NSCLCs and found 2 tumors with high-level (about 9-fold) amplification and 3 tumors with low-level (Ͻ3-fold) amplification. In that study, high-level amplification was observed only in 2ϩ and 3ϩ tumors.…”

Association of ERBB2 gene status with histopathological parameters and disease-specific survival in gastric carcinoma patients

“…Besides being a poor prognosis marker (Dowsett et al, 2003), ERBB2 amplification is a predictive marker for targeted therapy with the monoclonal antibody trastuzumab in breast cancer patients with metastatic disease (Slamon et al, 2001). More recently, trastuzumab was shown to be effective as adjuvant treatment in breast-carcinoma patients with ERBB2 amplification/ overexpression (Piccart-Gebhart et al, 2005;Romond et al, 2005).Apart from breast cancer, ERBB2 amplification has been found in other malignant tumours, such as ovarian (McKenzie et al, 1993), lung (Hirashima et al, 2001), colon (Cohen et al, 1989), and gastric carcinomas (David et al, 1992). Earlier studies in gastric carcinomas reported ERBB2 overexpression using immunohistochemistry (IHC) in 5.2 -22.6% of the cases, whereas the proportion Translational Therapeutics with ERBB2 amplification evaluated using fluorescence in situ hybridisation (FISH) ranged from 3.8 to 12.2% (Takehana et al, 2002;Varis et al, 2004;Park et al, 2006;Kim et al, 2007).…”

“…Apart from breast cancer, ERBB2 amplification has been found in other malignant tumours, such as ovarian (McKenzie et al, 1993), lung (Hirashima et al, 2001), colon (Cohen et al, 1989), and gastric carcinomas (David et al, 1992). Earlier studies in gastric carcinomas reported ERBB2 overexpression using immunohistochemistry (IHC) in 5.2 -22.6% of the cases, whereas the proportion Translational Therapeutics with ERBB2 amplification evaluated using fluorescence in situ hybridisation (FISH) ranged from 3.8 to 12.2% (Takehana et al, 2002;Varis et al, 2004;Park et al, 2006;Kim et al, 2007).…”