Fig 2: Model of MeHg transport across the placental barrier. a Schematic cross-section of a chorionic villus, as present in term placenta and b the placental barrier in detail. Here, the amino acid transporters LAT1 and LAT2, which are apically localized at the STB, are involved in MeHg-cysteine uptake in trophoblast cells. In the cell, MeHg dissociates from cysteine to bind to GSH. This MeHg-GSH conjugate is released by MRP1 that is expressed at the basal membrane of the STB. The subsequent mechanism and route of MeHg uptake in pFECs remains to be clarified. MRP1 is localized in pFECs, with expression at the luminal and abluminal plasma membrane, suggesting that MRP1 is involved in the transport of MeHg into fetal blood and possibly also into the placental stroma. References and further text are given in Chapter "The overall picture" (color figure online)

Fig 3: Effects of MeHg treatment and MRP1 downregulation on total Hg content, cell number, apoptosis, viability and cytotoxicity in HTR-8/SVneo cells. In a dose-dependent manner, MeHg exposure caused a an increase in cellular mercury content, b a decrease of cell number and c an increase of apoptosis relative to controls (w/o MeHg). In relation to controls (siPool) cell viability decreased (d) and cytotoxicity increased (e) after MeHg treatment in a dose-dependent manner. MRP1 knockdown intensified these effects. RLU: Relative Luminescence Unit; RFU: Relative Fluorescence Unit. The data represent mean values ± SD from three independent experiments, each performed in triplicates. a–c The letters A–G denote homogeneous subgroups derived from one-way ANOVA and S–N-K posthoc test (P < 0.05). d, e Asterisks denote significant differences between controls and MRP1 downregulated cells, *P < 0.05 from students t-test

Fig 4: PPP1R13L was involved in the TMEM44-AS1/miR-2355-5p-dependent impacts on GC cell resistance to 5-FU. A) Venn plot showing the four data sets. B) OS and DFS of GC patients (n = 112) with different PPP1R13L expression levels in their tumors. C) Linear regression analysis was done to each individual PPP1R13L and miR-2355-5p expression, r = -0.3222, p < 0.0001. D) RIP experiments were performed using the Ago2 antibody, and specific primers were used to detect the enrichment of PPP1R13L. E) Dual-luciferase gene reporter assays were used to assess the binding sites of PPP1R13L and miR-2355-5p. The relative luciferase activities were restrained in the HEK-293 T cells co-transfected with PPP1R13L-wt and miR-2355-5p. F) Transfection efficiency of si-PPP1R13L and oe-PPP1R13L was assessed by RT-qPCR and WB assays. G) The proliferative abilities of HGC 27/R and MKN-45/R cells subject to si-NC, si-PPP1R13L, oe-NC, or oe-PPP1R13L transfection were detected through EdU assay. Scale bar, 20 µm. H) The cell apoptosis rate was determined for the two GC cell lines with 5-FU resistance through flow cytometry. I) ABCC1, ABCG2, Caspase3, cleaved caspase-3, Survivin, and GAPDH protein expression was measured in HGC-27/R and MKN-45/R cells by western blotting. J) P53, AIFM2, Bcl-2, Bax, and GAPDH protein levels within HGC-27/R and MKN-45/R cells. 5 µg mL-1 5-FU was used to treat cells for a 48-h period before EdU assays, flow cytometric analysis, and protein extraction. Data are mean ± SD, n = 3. *P < 0.05, **P < 0.01, ***P < 0.001.

Fig 5: Protein expression differences in ABCB1, ACC and ABCG2 were detected through western blot analysis. In contrast to the parental cell lines (BxPC-3 and PANC-1 cells), protein expression of ABCB1 and ABCC was significantly increased with elevation of initial gemcitabine concentration in (A) BxPC-3/Gem cells while ABCG2 expression did not significantly change, and protein expression of ABCB1, ABCC and ABCG2 was considerably increased in (B) PANC-1/Gem cells. (C) Electrophoresis results of the 3 proteins, ABCB1, ABCC and ABCG2. ABCB1; ATP binding cassette subfamily B member 1; ABCC, ATP binding cassette subfamily C; ABCG2, ATP binding cassette subfamily G member 2.