Fig. 4

PDCD4 is a target gene of CASC9 and its expression correlates with clinical parameters in ESCC tissues. a Schematic flowchart showing the process of identifying PDCD4 as the target of CASC9. The combination of GO analysis and the gene expression correlation study identified PDCD4 in the cell growth pathways as potential regulatory target of CASC9. b Knockdown of CASC9 caused alterations in multiple pathways associated with cell growth. c Correlation analysis between CASC9 intensities and PDCD4 intensities provided by the microarray data from ESCC tissues. d Western blotting analysis showed that knockdown of CASC9 elevated the expression of PDCD4. e Spearman correlation was used to analyze the relationship between CASC9 and PDCD4 expression in another 37 ESCC tissues. f-h qPCR analysis of PDCD4 expression in ESCC tissues and adjacent normal tissues. PDCD4 expression was significantly lower in tumor tissues and especially lower in advanced pathological tumor samples. PDCD4 expression was higher in smaller tumor samples. Student’s t-test and one-way ANOVA analysis were performed to calculate the statistical difference. i Kaplan-Meier analysis showed that low PDCD4 expression indicated poor prognosis of ESCC patients. * P < 0.05, ** P < 0.01