Status of c‐erbB‐2 in gastric adenocarcinoma: A comparative study of immunohistochemistry, fluorescence in situ hybridization and enzyme‐linked immuno‐sorbent assay

Abstract

c-erb-2 amplification and overexpression are currently attracting a great deal of attention because a new adjuvant therapy using an antibody against the c-erbB-2 gene product, trastuzumab (Herceptin; Genentech, Inc., South San Francisco, CA), has proved effective in treating breast cancer with amplification and/or overexpression of c-erbB-2. Aberrations of c-erbB-2 have also been detected in ovarian, endometrial and gastric carcinomas at varied frequencies. Amplification of the c-erbB-2 locus (17q12-q21.32), overexpression of c-erbB-2 protein (p185) and serum levels of soluble c-erbB-2 protein fragments (p105) were examined in gastric cancer patients using fluorescence in situ hybridization (FISH), immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), respectively. Overexpression of c-erbB-2 protein was found in 29 (8.2%) of the 352 gastric carcinomas analyzed. In FISH analysis, all tumors with 3؉ immunostaining and 1 of 5 tumors with 2؉ staining showed high-level amplification of c-erbB-2. Pre-operative serum p105 was quantified in serum specimens from 129 patients with gastric cancer and 28 patients with benign diseases. There were no significant differences in the serum p105 levels among 11 patients with c-erbB-2-overexpressing carcinomas, 118 patients with c-erbB-2 non-overexpressing carcinomas and 28 controls, although a single case of gastric carcinoma overexpressing c-erbB-2 with extensive liver metastasis had a higher level than the cut-off value. The mechanisms of overexpression of p185 and highlevel amplification of c-erbB-2 in gastric adenocarcinomas seem similar to those well-established in breast cancers. Patients having gastric adenocarcinoma with c-erbB-2 amplification are potential candidates for a new adjuvant therapy using humanized monoclonal antibody.

Frequencies of HER-2/neu expression and gene amplification in patients with oesophageal squamous cell carcinoma

“…Three patients (4.5%) showed strong positive staining (3 þ ) and 6 (9.1%) showed moderate positive staining (2 þ ). With respect to FISH, a cell was considered to show amplification when a definite cluster or more than 10 orange signals of HER-2 was observed in accordance with earlier studies with FISH (Takehana et al, 2002). In FISH analysis for IHC-positive oesophageal SCC (n ¼ 20), HER-2 gene amplification (cluster, Figure 3) was found in seven tumours (Table 3).…”

“…Signals were counted for at least 40 cancer nuclei per tumour. In accordance with earlier studies with FISH, a cell was considered to show amplification when a definite cluster or more than 10 orange signals of HER-2 was observed (Takehana et al, 2002). A positive control, which is breast tumour with previously identified HER-2 amplification and overexpression, was used as a positive control for HER-2 FISH.…”

“…To determine the copy number for chromosome 17, we used CEP 17 as the control. FISH procedures were conducted according to the manufacturer's guidelines, except the removal of the protein from HER-2 in oesophageal squamous cell carcinoma K Mimura et al the section where we used our own protocol as described previously (Takehana et al, 2002). Briefly, sections were deparaffinised, dehydrated and incubated in 20% sodium bisulphate/ 2 Â standard saline citrate at 431C for 20 min.…”

“…The HER-2 proto-oncogene is amplified and overexpressed in approximately 30% of human ovarian and breast tumours (Slamon et al, 1989), and in 8.2% of gastric cancers (Takehana et al, 2002). The humanised monoclonal antibody (mAb) Herceptin, which specifically targets HER-2, exhibits potent growth inhibitory activity against HER-2-over expressing tumours (Sliwkowski et al, 1999).…”

Close association between HER-2 amplification and overexpression in human tumors of non-breast origin

“…For all of these tumor entities, HER-2 positivity (overexpression and/or amplification) had been previously described. [29][30][31][32] For example, HER-2 positivity for gastric cancer has been Of most tumor categories, we analyzed around 50 cases or even fewer. This rather low number raises the possibility that rare HER-2 amplification/overexpression may have been missed in some tumor entities.…”