Twenty‐one esophageal cancer cell lines (KYSE series) have been established from the resected specimens of patients with esophageal cancer. Three lines, KYSE‐30, KYSE‐50, and KYSE‐70, were derived from the implanted tumor of nude mice (initial passage); others were derived from resected specimens. Each cell line was morphologically distinct. Detailed cytogenetic analysis indicated that each cell line was karyotypically unique, and DNA fingerprint analysis showed no cross‐contamination among cells. Doubling time ranged from 13.7 to 75.5 hours, and modal chromosome numbers ranged from 46 to 120. Most cell lines grew in monolayer, but two cell lines (KYSE‐50 and KYSE‐360) grew as floating cell aggregates. No correlation was demonstrated between the establishment of cell lines and cell differentiation. These cell lines are the first reported to be homogeneous and individually unique and may provide a useful model for the study of human esophageal cancer.

Duodenal gastrinomas do not seem to behave as malignantly as sporadic pancreatic gastrinomas. Statistical analysis of 49 patients with sporadic pancreatic gastrinoma and 21 patients with sporadic duodenal gastrinoma reported since 1980 in Japan revealed that the incidence of hepatic metastasis was 57% in patients with sporadic pancreatic gastrinoma and only 9% in patients with sporadic duodenal gastrinoma (p less than 0.01). These findings suggest that there is an essential biological differences between duodenal and pancreatic gastrinoma. Five patients with sporadic duodenal microgastrinoma (tumor diameter less than 5mm) in our hospital had no hepatic metastases; however, 4 patients had lymph node metastases. Immunohistochemical study of 5 sporadic duodenal microgastrinomas and 6 sporadic pancreatic gastrinomas revealed that the sporadic duodenal gastrinomas contained significantly fewer insulin-producing or glucagon-producing cells than sporadic pancreatic gastrinomas. The cellular composition of the metastatic lymph nodes from duodenal microgastrinomas was similar to that of the primary tumor. This difference in cellular composition between the duodenal microgastrinomas and the pancreatic gastrinomas suggests that the process of development and differentiation of gastrinoma cells is different.

An increasing number of studies have shown that thep53 gene is one of the most frequently mutated genes in avariety of human tumors including human esophageal squamous cell carcinomas (ESC). To date, several reports on ESCs have shown that the frequent loss of 17p and mutations of thcp.73 genc wcrc associated, and thcsc mutations wcrc found in approximately one-half of resected specimens studied (Bennett et al., 1991;Hollstein et al., 1991;Wagata et al., 1993;Greenblatt et al., 1994). Furthermore, immunohistochemical analyses using specific antibodies showed that abnormal accumulation ofp53 protein, which is correlated with mutations of the p53 gene, was recognized at the pre-cancerous stages, such as basal cell hypcrplasia or dysplasia of the esophagus, suggcsting thatp53 mutations arc important even in the early stagc of ESC carcinogenesis (Wang et al., 1992;Gao et al., 1994).Moreover, mutation of the p53 gene seems to be advantageous for growth of cells in vitro in addition to in vivo tumor development. Dramatic growth inhibition of human colorectal and lung adenocarcinoma cells induced by the expression of the introduced wild-type p53 genc indicates that the loss of function o f thc p53 gene provides a selective advantage for clonal expansion of pre-neoplastic and neoplastic cells (Baker et al., 1990). A recent review on mutational analysis of thep53 gene showed that mutations in cell lines were found twice as frequently as in their corresponding in vivo tumor specimens but mutation spectra in cell lines reflect in vivo carcinogens (Greenblatt et al., 1994). These results suggest that tumors withp.53 mutations may be more liable to be established as cell lines. In contrast, a study on head and neck cancers and cell lines revealed that the presence ofp53 gene mutations was not by itself sufficient for establishment as cell lines (Sakai et a/., 1992). To elucidate whether thep53 mutations in ESCs are related to their establishment in cell culture, we screenedp53 mutations in 29 human ESC cell lines and compared their mutation frequencies and spectra with those in 65 resected tumors of ESC. MATERIAL AND METHODS Cell lines and resected specimensTwenty-nine cell lines were established from pathologically confirmed primary ESCs and maintained in Ham's F12/RPMI 1640 medium with 2% FCS, as described previously (Shimada et al., 1992). These cell lines are indicated by KYSE and numbers. Tumor tissues were obtained from 65 Japanese patients with ESC, who underwent surgery at the Kyoto University Hospital, and were stored at -80°C. All of these tumors were described in our previous study (Shibagaki et al., 1995). We tried to establish cultured cell lines with all 65 tumor samples but succeeded in establishing only 10 cell lines, which were included in the 29 cell lines mentioned above. Genomic DNA and total RNA were extracted from the cell lines or frozen tumors by a standard method (Shibagaki etal.. 1995). PCR-SSCP analysisPCR was performed in a 50-pI reaction mixture containing 100-150 ng genomic DNA; 20 pmol each prim...

An increasing number of studies have shown that thep53 gene is one of the most frequently mutated genes in avariety of human tumors including human esophageal squamous cell carcinomas (ESC). To date, several reports on ESCs have shown that the frequent loss of 17p and mutations of thcp.73 genc wcrc associated, and thcsc mutations wcrc found in approximately one-half of resected specimens studied (Bennett et al., 1991;Hollstein et al., 1991;Wagata et al., 1993;Greenblatt et al., 1994). Furthermore, immunohistochemical analyses using specific antibodies showed that abnormal accumulation ofp53 protein, which is correlated with mutations of the p53 gene, was recognized at the pre-cancerous stages, such as basal cell hypcrplasia or dysplasia of the esophagus, suggcsting thatp53 mutations arc important even in the early stagc of ESC carcinogenesis (Wang et al., 1992;Gao et al., 1994).Moreover, mutation of the p53 gene seems to be advantageous for growth of cells in vitro in addition to in vivo tumor development. Dramatic growth inhibition of human colorectal and lung adenocarcinoma cells induced by the expression of the introduced wild-type p53 genc indicates that the loss of function o f thc p53 gene provides a selective advantage for clonal expansion of pre-neoplastic and neoplastic cells (Baker et al., 1990). A recent review on mutational analysis of thep53 gene showed that mutations in cell lines were found twice as frequently as in their corresponding in vivo tumor specimens but mutation spectra in cell lines reflect in vivo carcinogens (Greenblatt et al., 1994). These results suggest that tumors withp.53 mutations may be more liable to be established as cell lines. In contrast, a study on head and neck cancers and cell lines revealed that the presence ofp53 gene mutations was not by itself sufficient for establishment as cell lines (Sakai et a/., 1992). To elucidate whether thep53 mutations in ESCs are related to their establishment in cell culture, we screenedp53 mutations in 29 human ESC cell lines and compared their mutation frequencies and spectra with those in 65 resected tumors of ESC. MATERIAL AND METHODS Cell lines and resected specimensTwenty-nine cell lines were established from pathologically confirmed primary ESCs and maintained in Ham's F12/RPMI 1640 medium with 2% FCS, as described previously (Shimada et al., 1992). These cell lines are indicated by KYSE and numbers. Tumor tissues were obtained from 65 Japanese patients with ESC, who underwent surgery at the Kyoto University Hospital, and were stored at -80°C. All of these tumors were described in our previous study (Shibagaki et al., 1995). We tried to establish cultured cell lines with all 65 tumor samples but succeeded in establishing only 10 cell lines, which were included in the 29 cell lines mentioned above. Genomic DNA and total RNA were extracted from the cell lines or frozen tumors by a standard method (Shibagaki etal.. 1995). PCR-SSCP analysisPCR was performed in a 50-pI reaction mixture containing 100-150 ng genomic DNA; 20 pmol each pri...