w the overexpression of PD-L1 ([Figure 3A](#F3){ref-type="fig"}). Interestingly, the expression level of HDAC10 is positively correlated with PD-L1 expression in NSCLC tissue (*r* = 0.213, *P* \< 0.05). To provide evidence that the positive relationship of HDAC10 and PD-L1 (CD274) in patients with NSCLC, the correlation of these two targets (HDAC10 and CD274) was analyzed (<https://hgserver1.amc.nl/cgi-bin/r2/main.cgi>). As shown in [Figure 3B](#F3){ref-type="fig"}, the expression level of HDAC10 is positively associated with CD274 expression in patients with NSCLC (p=0.020, n=410). This result further confirmed our findings.

![The expression level of PD-L1 in patients with NSCLC. **(A)** The expression level of PD-L1 in all types of cancer, data were from the Protein Atlas website: <https://www.proteinatlas.org/ENSG00000120217-CD274/pathology>; **(B)** lung tumor tissue and para-cancer lung tissue were stained with PD-L1 antibody. Using both the IHC staining intensity and proportion of cell stained, the IHC score was determined by a semi-quantitative method. The expression level was further classified into low expression (≤1), moderate expression (1.5-6) and strong positive expression (≥7.5) for PD-L1. A reprehensive image of high-, medium- and low-level of PD-L1 expression in tumor tissue from 180 patients with NSCLC receiving pulmonectomy (a, b, c), and PD-L1 expression in its corresponding para-cancer tissue (d).](fonc-10-00485-g0002){#F2}

![The expression of HDAC10 is positively associated with PD-L1 expression in patients with NSCLC receiving pulmonectomy. **(A)** Correlation between HDAC10 and PD-L1 expression in NSCLC tissues was analyzed. HDAC10 is positively correlated with PD-L1 expression in NSCLC (*r* = 0.213, *p* \< 0.05). **(B)** The HDAC10 expression is positively associated with PD-L1 (CD274) in patients with NSCLC (*p* = 0.02). Data were from the R2 website. (<https://hgserver1.amc.nl/cgi-bin/r2/main.cgi>).](fonc-10-00485-g0003){#F3}

High-Level HDAC10 Expression Is Associated With a Poor 