Katoiii

The gastric cancer cell lines MKN74, Kato-III, SH-10-TC (Riken Bioresource Center, Tsukuba, Japan), AGS (ATCC), SNU216, SNU484, SNU601, SNU638, SNU668, and SNU719 (Korean Cell Line Bank, Seoul, Korea) were cultured in RPMI1640 or DMEM supplemented with 10% FBS. All cell lines were authenticated by an isoenzyme analysis or short tandem repeat analysis and initially expanded and cryopreserved within one month of receipt. Cells were used within three months after thawing frozen vials. The construction of WT-ER FOXO3- and Act-ER FOXO3-expressing cells is indicated in Supplementary Information.
For the colony formation assay, 2 × 10³ cells were cultured in a 6-well plate in the presence or absence of tamoxifen (Sigma-Aldrich) at 1 μM for 10 days. Cells were then stained with Giemsa solution, and the colony numbers per well were counted. For the cell proliferation analysis, 1 × 10³ cells were seeded in a 96-well plate, and the cell viability was examined with a Cell Titer-Glo Cell Viability Assay (Promega, Madison, WI). The luciferase activity was measured by a Centros XS³ LB960 (Berthold Technologies, Bad Wildbad, Germany). All cell culture experiments were repeated three times. Mycoplasma testing was performed using a direct immunofluorescence test.

The human GC cell lines HGC-27, Kato III, and MKN45 were purchased from RIKEN BioResource Center, Tokyo, Japan. These cell lines were maintained in RPMI medium (Nacalai Tesque, Kyoto, Japan) supplemented with 10% fetal bovine serum, 100 U/ml of penicillin and 100 μg/ml of streptomycin. The flasks were kept in a humidified incubator at 37°C with 5.0% CO² in air. Quin, a potassium channel blocker, was purchased from Nacalai Tesque.

Human gastric cancer cell lines (MKN7, MKN45, MKN74, KATOIII, and NUGC3) were purchased from the Riken Bioresource Center (Cell Bank, Ibaraki, Japan) and the Japanese Collection of Research Bioresources (JCRB Cell Bank, Osaka, Japan). All cell lines were cultured in culture medium (RPMI 1640 medium [Sigma-Aldrich, St. Louis, MO] containing 10% heat-inactivated fetal bovine serum [FBS, Life Technologies, Carlsbad, CA], 100 U/mL of penicillin, 100 μg/mL of streptomycin, and 0.25 μg/mL of amphotericin B [Antibiotic-Antimycotic; Life Technologies]) at 37°C in 5% CO₂ with 95% humidity.

Seven gastric cancer cell lines were used: four cell lines with wt TP53 (MKN-45, NUGC-4, STKM-2, SNU-1), two cell lines with mutant-type (mt) TP53 (NUGC-3, STKM-1), and one cell line with null TP53 (KatoIII) [19] (link)–[21] (link). Cell lines with wt TP53 (MCF-7 breast cancer, HEK293 human embryonic kidney cells) and MRC-5 normal human fibroblasts were included as controls in this study. MKN-45, NUGC-4, KatoIII, and MRC-5 cell lines were obtained from RIKEN BRC Cell Bank (Tsukuba, Japan). SNU-1 and MCF-7 cell lines were purchased from the American Type Culture Collection (Rockville, MD). NUGC-3 and HEK293 cell lines were obtained from Health Science Research Resources Bank (Osaka, Japan). STKM-1 and STKM-2 cell lines were kindly provided by Dr. Shunsuke Yanoma (Yokohama City University, School of Medicine, Japan).

The human gastric cancer cell lines KatoIII (RCB2088), MKN45 (RCB1001), and MKN74 (RCB1002) were purchased from RIKEN Bio Resource Center (Tokyo, Japan), and the human normal mesothelial cell line MeT-5A (CRL-9444) was purchased from ATCC (Manassas, VA, USA). These cell lines were maintained in RPMI medium (Nacalai Tesque, Kyoto, Japan) supplemented with 10% exosome-depleted fetal bovine serum (System Biosciences, CA, USA), 100 U/mL penicillin and 100 μg/mL streptomycin. The flasks were kept in a humidified incubator at 37°C with 5.0% CO₂.