Expression of EGFR and c-erbB-2 in Esophageal, Gastric and Colonic Cancer and in Human Gastric Cancer Xenografts of Nude Mice

Takashi Mizutani, Masahiko Onda, Akira Tokunaga

First Department of Surgery, Nippon Medical School

Epidermal growth factor receptor (EGFR) shares homology with, but is distinct from, c-erbB-2 oncoprotein. While amplification of EGFR is found in both squamous cell carcinoma and adenocarcinoma, that of the c-erbB-2 gene is found only in adenocarcinoma. EGFR is shown to be coexpressed with c-erbB-2 in advanced gastric cancer with metastasis. This study was, therefore, designed to examine the expression of EGFR in human gastric cancer in comparison with esophageal and colonic cancer, and to examine the presence of c-erbB-2 in human gastric cancer xenografts of nude mice. The expression of EGFR was examined by ¹²⁵I-EGF binding assay. Slot blotting and immunohistochemistry for c-erbB-2 were also done. EGF binding capacity of non-cancerous mucosa and cancer in esophagus was higher than that in stomach or colon. EGF binding capacity and the positive rate of EGFR in gastric cancer were higher than those in non-cancerous gastric mucosa, and those in undifferentiated gastric carcinoma were higher than those in differentiated gastric carcinoma. No difference in EGF binding capacity and the positive rate of EGFR was found in non-cancerous mucosa and cancer of colon. Both amplification and protein expression of c-erbB-2 were found in two differentiated adenocarcinomas of human gastric cancer xenografts in nude mice. The expression of EGFR and/or c-erbB-2 appeared to be related to the growth of human gastric cancer and its xenografts in nude mice. However, it is open to question whether coexpression of EGFR and c-erbB-2 in the tumor contribute to metastasis and/or invasion of cancer cells.

Key words
epidermal growth factor receptor, c-erbB-2, esophageal cancer, gastric cancer, colonic cancer

Reprint requests
Takashi Mizutani First Department of Surgery, Nippon Medical School
1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113 JAPAN

Accepted
February 10, 1993

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