Established gastric cancer cell lines transplantable into C57BL/6 mice show fibroblast growth factor receptor 4 promotion of tumor growth

Previously no mouse gastric cancer cell lines have been available for transplantation into C57 BL /6 mice. However, a gastric cancer model in immunocompetent mice would be useful for analyzing putative therapies. N ‐Methyl‐ N ‐nitrosourea ( MNU ) was given in drinking water to C57 BL /6 mice and p53 heterozygous knockout mice. Only 1 tumor from a p53 knockout mouse could be cultured and the cells s.c. transplanted into a C57 BL /6 mouse. We cultured this s.c. tumor, and subcloned it. mRNA expression in the most aggressive YTN 16 subline was compared to the less aggressive YTN 2 subline by microarray analysis, and fibroblast growth factor receptor 4 ( FGFR 4) in YTN 16 cells was knocked out with a CRISPR /Cas9 system and inhibited by an FGFR 4 selective inhibitor, BLU 9931. These transplanted cell lines formed s.c. tumors in C57 BL /6 mice. Four cell lines ( YTN 2, YTN 3, YTN 5, YTN 16) were subcloned and established. Their in vitro growth rates were similar. However, s.c. tumor establishment rates, metastatic rates, and peritoneal dissemination rates of YTN 2 and YTN 3 were lower than for YTN 5 and YTN 16. YTN 16 established 8/8 s.c. tumors, 7/8 with lung metastases, 3/8 with lymph node metastases and 5/5 with peritoneal dissemination. FGFR 4 expression by YTN 16 was 121‐fold higher than YTN 2. FGFR 4‐deleted YTN 16 cells failed to form s.c. tumors and showed lower rates of peritoneal dissemination. BLU 9931 significantly inhibited the growth of peritoneal dissemination of YTN 16. These studies present the first transplantable mouse gastric cancer lines. Our results further indicate that FGFR 4 is an important growth signal receptor in gastric cancer cells with high FGFR 4 expression.