Synergistic antitumor effects of FGFR2 inhibitor with 5-fluorouracil on scirrhous gastric carcinoma.

Scirrhous gastric carcinoma (SGC) carries the highest mortality because of a frequent metastasis to lymph node (LN). S1, a 5-fluorouracil (5-FU) analog, is clinically available for gastric cancer at an advanced stage. Fibroblast growth factor receptor 2 (FGFR2) is required for the proliferation of SGC. The objective of this study is to clarify the benefit of a combination of S1 and kinase inhibitors including FGFR2 inhibitor Ki23057 in gastric cancer. OCUM-2MLN and KATO-III were derived from SGC. MKN-7 and MKN-74 were derived from non-SGC. MTT assay was used to examine the growth-inhibitory activity of 5 small-synthetic molecules including Ki23057, Sunitinib, Glivec, Lapatinib or SU11274, in cells cultured with 5-FU. Combination effects of 5-FU with Ki23057 on proliferation, apoptosis and mRNA expression were examined. S1 and/or Ki23057 were administered to murine models of SGC created by the orthotopic inoculation of OCUM-2MLN cells. Ki23057 at 100 nM significantly (p < 0.01) inhibited the proliferation and decreased the phosphorylation of FGFR2 in SGC cells, but not in non-SGC. Ki23057 showed synergistic antitumor effects for SGC cells in combination with 5-FU using CalcuSyn analysis, but Sunitinib, Glivec, Lapatinib and SU11274 did not. The combination of Ki23057 and 5-FU decreased DPD expression and increased apoptosis rates and p21 expression level of SGC cells. The combined administration of S1 and Ki23057 significantly (p < 0.05) decreased orthotopic tumors as well as LN metastasis more effectively than S1 alone. These findings suggested that the combined treatment with 5-FU and Ki23057 produced synergistic antitumor effects and is therapeutically promising for SGC treatment.