Fig. 2
The activation of calcium-sensing receptor (CaSR) is required for spermine-induced PD-L1 expression in HCC. A Immunohistochemical staining of CaSR in the matched adjacent normal tissues and tumor tissues. ***p < 0.001, two-tailed unpaired t test, n = 24 samples per group. B, C Effects of spermine on the expression of CaSR Mrna (B) and protein (C) in SNU-368 cells. One-way ANOVA, n = 5 independent experiments per group. D Representative tracings of [Ca2+]cyt changes in response to 200 µM spermine in the presence or the absence of NPS2134 (10 µM) in SUN368 cells. I Analysis of the changes in F340/F380 at 400 s after the stimulation with spermine in the presence or the absence of NPS2134. **p < 0.01, two-tailed unpaired t test, n = 4 independent experiments per group. F, G Effects of pretreatment with CaSR antagonist NPS2134 (10 µM; “NPS”) on the spermine-induced expression of CD274 Mrna (F) and PD-L1 protein (G) in SNU-368 cells. *p < 0.05, **p < 0.01, ***p < 0.001, one-way ANOVA, n = 5 independent experiments per group. H, I Effects of pretreatment with Ca2+ chelator BAPTA-AM (10 µM; “BAPTA”) on the spermine-induced expression of CD274 mRNA (H) and PD-L1 protein (I) in SNU-368 cells. *p < 0.05, **p < 0.01, ***p < 0.001, one-way ANOVA, n = 4 independent experiments per group