cancer Letters 75 (1993) 41-44

CANCER LETTERS

HER-2/neu: a differentiation marker in adenocarcinoma of the esophagus

Edward R. Sauter*“, Steven M. Keller”, Susan Ernerb, Melvyn Goldbergb

uDepartment qf‘ Surgery. hDepartment of Pathology, FO.Y Chase Cancer Center. Philadelphia. PA 19111. USA

(Received 2 September 1993; accepted 9 September 1993)

Abstract

Adenocarcinoma of the esophagus is an aggressive malignancy which is increasing in frequency. The HER-2inru oncogene product is a putative differentiation marker which exhibits decreased expression in colon carcinoma, while there is overexpression in breast and ovarian cancers. We analyzed the relationship of cell differentiation to HER-2ineu expression in esophageal adenocarcinoma using immunohistochemistry on formalin-fixed, paraffin-embedded material from 14 patients whose tissue contained normal, dysplastic, and malignant features. HER-~/MU expression was detected in 1 of 14 biopsy specimens and 2 of 9 resection specimens. The oncoprotein staining was greatest in normal tissue, less in dysplastic tissue, and not detected in malignant tissue. Our findings. similar to what is seen in the colon, suggest that the HER-Z/MU oncogene product is a differentiation marker which is lost in esophageal adenocarcinoma.

Key words: HER-~/MU; Differentiation marker; Esophageal adenocarcinoma

1. Introduction

The neu gene encodes a transmembrane glyco- protein with tryrosine-specific protein kinase ac-

tivity [7]. Also known as erbB-2, NGL, and HER-2, amplification and overexpression of this gene has been associated with a worse prognosis in a number of malignancies, including breast, ovary, stomach, and salivary gland [9-l 11. Prominent ex- pression of the gene is found in normal epithelium of the gastrointestinal (GI) tract, including liver, pancreas, stomach, small and large intestine [2].

* Corresponding author.

There is evidence that neu is a growth factor receptor [3]. Its expression appears to be tissue specific [2]. Increased expression of the gene has been found in benign adenomas of the colon [4] with an inverse relationship between neu expres- sion and malignant degeneration, so that malig- nant tissues and polyps with severe dysplasia

exhibit less neu expression than benign tumors and normal epithelium. It has been speculated, therefore. that loss of nezc expression may con- tribute to abnormal cell growth, and that. at least in some intestinal tumors, neu may serve as a dif- ferentiation marker [2]. We evaluated neu expres- sion in histologically normal, dysplastic. and

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42 E.R. Saurer el ul. / C'unwr Lrii. 7S (1993: 41-44

malignant tissue taken from patients diagnosed

with adenocarcinoma of the esophagus and gastroesophageal junction.

2. Materials and methods

Between April 1987 and June 1992, one female and 13 male patients with localized. biopsy-proven adenocarcinoma of the esophagus and gastro- esophageal junction were treated on protocol in-

volving preoperative concurrent high dose (60 Gy) radiation and chemotherapy (5-fluorouracil and mitomycin C). All patients subsequently under- went laparotomy, and 11 were resected for cure.

Fourteen diagnostic biopsies and nine esophagec- tomy specimens containing residual tumor were available for review.

Immunohistochemicai analysis was performed

using the avidin-biotin-immunoperoxidase tech- nique. Briefly, tissue sections were deparaffinized and rehydrated in graded alcohols. Endogenous peroxide activity was quenched with methanol in

hydrogen peroxide. Incubation in blocking serum was carried out prior to the application of primary antibody. A mouse monoclonal primary antibody to a ~185 HER-2ineu synthetic peptide (10 pg/ml

final working concentration; Oncogene Sciences) was used. The secondary antibody was horse anti- mouse IgG ( 1: 100 dilution; Vector Laboratories). The reaction was developed using an avidin-

biotin-peroxidase complex (1:25 dilution; Vector Laboratories). The chromagen 3 ‘3 ’ diaminoben- zidine was used to identify sites of im- munoprecipitation. A breast carcinoma known to

overexpress nezl and esophageal epithelium without primary antibody were used as positive and negative controls.

3. Results

Three of fourteen patients exhibited membran- ous and cytoplasmic neu expression, including one of 14 biopsy specimens and 2/9 resection speci- mens (Table 1). There was a gradual decrease in staining intensity from normal epithelium to in- vasive cancer (Figs. 1 and 2). The third patient had Barrett’s changes in all tissue sections, with mem- branous and cytoplasmic staining in the Barrett’s

Table 1 Staining pattern in patients with MU expression

Patient Normal

epithelium Dysplasia Adenocarcinoma

I ++ + 0 2 + 0 0 3 ++ ++ f

epithelium, while the invasive cancer had only marginal staining. The small number of patients

precluded attempts at associating neu expression with patient prognosis.

4. Discussion

Both amplification [9] of the neu oncogene and overexpression of its protein product have been as- sociated with poor prognosis in breast cancer [l]. Amplification is frequently, though not always, as-

sociated with protein overexpression [4]. In some studies which associated neu expression with poor prognosis, the presence of the oncogene was cor- related with advanced disease [ 10,111.

There is good evidence that neu is a growth fac- tor receptor. It has close homology to epidermal growth factor receptor (EGFR) [3]. EGFR and

neu appear to have been derived from a common ancestral gene [8].

The mechanisms explaining neu expression in normal colon epithelium, increased expression in

benign adenomas and decreased expression in ma- lignant cells is unclear. Cohen et al. [2] hypothesiz- ed that a genetic mutation (e.g., gene deletion) resulted in loss or aberration of normal regulatory

function provided by neu, which may contribute to abnormal cell growth.

Jankowski et al. [6] reported on neu expression in 15 patients with adenocarcinoma of the

esophagus, indicating that 73% of the tumors ex- pressed neu. This is in contrast to the findings of Houldsworth [5], who found that of the 28 esophageal and gastric adenocarcinomas which they evaluated, no patient with a carcinoma of the esophagus or cardia of the stomach had amplifica- tion of neu, and to our finding that 0114 adenocar- cinemas of the esophagus and gastroesophageal

Fig. 1. Area of normal (N) epithelium (x 10) with positive staining for HER-2inru, but no staining above background from same

patient in the area containing tumor (T).

Fig. 2. Enlargement ( x 40) from the area of normal epithelium.

44 E. R. Suuirr er ~1. / Currcrr Leti. 75 ( 1993) 41-44

junction had clear evidence of neu expression. The explanation for this difference is unclear, although Jankowski mentions that the expression his group found was very high compared to that found by others in a variety of gastrointestinal malignancies.

In summary, our findings suggest that neu onco- gene overexpression is found in the epithelium sur- rounding tumor in some patients with adenocar- cinema of the esophagus. This epithelial expres- sion is gradually lost with malignant degeneration of the cells, similar to what is seen in adenocar- cinema of the colon. The HER-Yneu protein

product may serve as a differentiation marker in these patients.

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