Fig. 1

PLCE1 is upregulated in ESCC through aberrant promoter hypomethylation. a IHC staining of PLCE1 expression in human ESCC (clinical stages I–IV) and normal esophageal tissues. b Kaplan-Meier overall survival curves for patients with ESCC stratified by low (n = 21) and high (n = 129) expressions of PLCE1 (P = 0.002). c GEO data (GSE9982) analysis of PLCE1 mRNA expression in normal esophageal cell lines (n = 20) and esophageal cancer cell lines (n = 20). ***P < 0.0009, unpaired two-tailed Student’s t-test. d Analysis of PLCE1 gene expression in tumor and adjacent non-tumor tissues in NCBI/GEO/GSE23400 (P = 0.004). e GEPIA analysis of PLCE1 expression in cancerous and normal tissues. ESCA: esophageal carcinoma; LAML: Acute Myeloid Leukemia; LIHC: Liver hepatocellular carcinoma; *P < 0.05. f GEO data analysis for the expression of PLCE1 by two-tailed t test (*P < 0.05, **P < 0.01, ***P < 0.001). g Genomic structure of PLCE1 CpG dinucleotides over TSS and hierarchical cluster analysis of CpG units’ methylation profiles of PLCE1 promoter region in ESCC (n = 132) and normal (n = 104). Each vertex indicates one CpG site. Each column represents one sample. Rows are clustering of CpG units, which are single CpG sites or a combination of CpG sites. Color gradient between white and red indicates methylation of each PLCE1 CpG unit in each sample (0–56%). Black represents inadequate or missing data. h Comparison of average methylation of PLCE1 promoter of ESCC and normal subjects. The overall methylation level of the target fragment of the PLCE1 promoter was statistically lower (0.0957 ± 0.0456) in ESCC than that in normal tissues (0.1144 ± 0.0464, P = 0.0001). i Box plot of 6 CpG units in PLCE1 promoter between ESCC and normal tissues. Red and blue spots represent methylation status of one CpG site in ESCC and normal tissues. Dark spots are outliers. In addition to CpG_3 an d CpG_4, the mean methylation levels at CpG_2, CpG_5.6, CpG_7.8, and CpG_9.10 were significantly lower in patients with ESCC (mean methylation = 20.25, 11.84, 8.07, 7.20%, respectively) than those in the controls (mean methylation = 32.38, 13.89, 10.52, 9.37%, respectively; all the P < 0.05), *P < 0.05, **P < 0.01, ***P < 0.001 (Mann–Whitney U-test). j The methylation status of 6 CpG site was all negatively correlated with PLCE1 expression in TCGA Illumina 450 k infinium methylation beadchip. k Kaplan-Meier analysis of survival time according to PLCE1 CpG methylation in ESCC patients