We have established a human gastric scirrhous carcinoma cell line (designated as HSC-43) in a serum-free chemically defined medium (CDM) without any polypeptide growth factor, from a primary tumor of a 56-year-old male patient. HSC-43 cells grew in vitro in adherence with a population doubling time of 55 hr, and had the cytological properties of mucinous epithelial tumor cells. Cytogenetic analysis of the cells revealed pseudotetraploidy, with structural abnormalities of deletion at chromosome Iq25 and with 3 marker chromosomes. Some cells had retained features of signet-ring cells and caused fibroblastic proliferation when transplanted into athymic nude mice. The possible involvement of transforming growth factor-alpha (TGF-alpha), and its receptor, the epidermal-growth-factor receptor (EGFR), on the growth of HSC-43 cells was studied. Synthesis and secretion of TGF-alpha by HSC-43 cells were confirmed by biological assay and enzyme-linked immunosorbent assay. Radioreceptor analysis showed the presence of receptors for EGF in HSC-43 cells. Proliferation of HSC-43 cells was inhibited by antibodies against TGF-alpha and/or the EGFR. However, neither TGF-alpha nor epidermal growth factor (EGF) was effective in stimulating the cell growth of HSC-43 cells, irrespective of the cell density when supplemented exogenously. Our data suggest that TGF-alpha and EGFR play a role in the autocrine growth of HSC-43 cells. This may be another example of growth regulation of gastric carcinoma.