Purpose: Appropriate preclinical mouse models are needed to evaluate the response to immunotherapeutic agents. Immunocompetent mouse models have rarely been reported for gastric cancer. Thus, we investigated immunophenotypes and responses to immune checkpoint inhibitor (ICI) in immunocompetent mouse models using various murine gastric cancer cell lines. Materials and Methods: We constructed subcutaneous syngeneic tumors with murine gastric cancer cell lines, YTN3 and YTN16, in C57BL/6J mice. Mice were intraperitoneally treated with IgG isotype control or an anti–programmed death-ligand 1 (PD-L1) neutralizing antibody. We used immunohistochemistry to evaluate the tumor-infiltrating immune cells of formalin-fixed paraffin-embedded mouse tumor tissues. We compared the protein and RNA expression between YTN3 and YTN16 cell lines using a mouse cytokine array and RNA sequencing. Results: The mouse tumors revealed distinct histological and molecular characteristics. YTN16 cells showed upregulation of genes and proteins related to immunosuppression, such as Ccl2 (CCL2) and Csf1 (M-CSF). Macrophages and exhausted T cells were more enriched in YTN16 tumors than in YTN3 tumors. Several YTN3 tumors were completely regressed by the PD-L1 inhibitor, whereas YTN16 tumors were unaffected. Although treatment with a PD-L1 inhibitor increased infiltration of T cells in both the tumors, the proportion of exhausted immune cells did not decrease in the non-responder group. Conclusion We confirmed the histological and molecular features of cancer cells with various responses to ICI. Our models can be used in preclinical research on ICI resistance mechanisms to enhance clinical efficacy.

Background: This study aimed to examine the association between coffee or green tea consumption and ferritin or hemoglobin levels in premenopausal women. Methods: We used the fifth Korea National Health and Nutrition Examination Survey (2010–2012), and a total of 4,322 individuals were surveyed. In women of reproductive age, average ferritin and hemoglobin levels were calculated according to coffee or green tea consumption. Covariates included in the analysis were demographic variables, such as age, body mass index, education, drinking, smoking, history of hypertension, history of diabetes diagnosis, physical activity, total energy intake, and daily iron intake. Results: In 4,322 participants, the average hemoglobin level was 12.90±0.02 g/dL, and the average level of ferritin was 31.95±0.67 ng/mL. As a result of testing, correlation between ferritin and coffee intake and difference in ferritin levels according to coffee consumption was significant (P<0.05). In this study, a post hoc test indicated that ferritin level significantly differed between one and two cups, two and three cups, and three and one cup groups (overall P<0.001). Additionally, there was a negative correlation between ferritin level and coffee intake; ferritin level decreased by 2.09 ng/mL with a one-cup increase in daily coffee consumption. Conclusion In premenopausal women, coffee intake is associated with low serum ferritin levels. Our results indicate that drinking >2 cups of coffee significantly affect ferritin levels in Korean premenopausal women.