Fig 2: GRIN2D promotes PDAC progression by CREB/ p38 MAPK signaling pathway. (A). p38, MSK, and CREB were dephosphorylated after knockdown of GRIN2D in SW1990 and PANC04.03 cells. (B). Clinical correlation between GRIN2D and p-CREB levels in PDAC primary tumors. (C). Amount of common differential genes in SW1990 and PANC04.03 cells after knockdown of GRIN2D. (D). Expression of differential genes after knockdown of GRIN2D. (E). Correlation between GRIN2D and IL20RB, CCL22, G5S2, IL6, EPGN, and HMGA2 expression in PDAC tumors. (F). IL20RB, CCL22, G5S2, IL6, EPGN, and HMGA2 expression in tumor and non- tumor groups from two independent samples cohort GSE16515 and GSE15471. (G). Survival analysis of IL20RB, CCL22, G5S2, IL6, EPGN, and HMGA2 in PDAC patients. (H). Phosphorylated CREB binding to HMGA2 and IL20RB in SW1990 and PANC04.03 cells, as revealed by ChIP assay. (I). EMT markers ZEB1, SNAIL, SLUG, and TWIST were downregulated after knockdown of GRIN2D in SW1990 and PANC04.03 cells. Data are from at least three independent experiments. Mean ± SD. *, P < 0.05; **, P < 0.01; ***, P < 0.001

Fig 3: GRIN2D was identified as an oncogene in PDAC. (A). Workflow of in-vivo genome-wide RNAi screening. (B). GRIN2D was upregulated in PDAC cells, as compared to non-tumor HPDE cells. (C). IHC staining of GRIN2D in blood vessels and ducts with the respective markers PECAM-1 and CK19. GRIN2D was upregulated in PDAC tumor tissues, compared to adjacent non- tumor tissues. (D). GRIN2D expression was increased in PDAC tumors, as compared to normal, from two independent samples cohort GSE16515 and GSE15471. Data are from at least three independent experiments. Mean ± SD. *, P < 0.05; **, P < 0.01; ***, P < 0.001

Fig 4: GRIN2D promoted tumor growth and liver metastasis in PDAC. (A). GRIN2D was knocked down by stable lentiviral shRNA system in SW1990 cells. (B). Knockdown of GRIN2D inhibited tumor growth in SW1990 cells. Photographs of mice xenograft at day 28 after knockdown of GRIN2D in SW1990 cells. (C). Tumor volume and tumor mass of xenograft mice after knockdown of GRIN2D. (D). IHC staining of Ki67, H&E Staining in mice subcutaneous tumors after knockdown of GRIN2D. (E). Knockdown of GRIN2D inhibited liver metastasis in SW1990 cells

Fig 5: Memantine is a potential drug for PDAC therapy. (A). Dose-response curve of memantine in PDAC cells. (B). Cell growth was inhibited in memantine treated PDAC cells, as revealed by CCk8 cell viability assay. (C). Cell migration was inhibited in memantine treated PDAC cells, as revealed by wound healing cell migration assay. (D). Clonogenic ability was inhibited in memantine treated PDAC cells, the cells in the colony formation assay were stained by crystal violet. (E). Level of GRIN2D decreased in memantine treated PDAC cells. (F). p38, MSK, and CREB in p38 MAPK signaling pathway were dephosphorylated after treatment of memantine. Data are from at least three independent experiments. Mean ± SD. *, P < 0.05; **, P < 0.01; ***, P < 0.001