Interfering CASC9 suppressed ESCC cell growth and blocked cell cycle G1/S transition in vitro, as well as inhibited tumorigenesis in nude mice.30 It functioned via suppressing PDCD4 expression by recruiting enhancer of zeste homolog 2 and subsequently altering H3K27me3 level in PDCD4 promoter.30 CASC9 also facilitated ESCC metastasis via elevating LAMC2 expression by regulating CREB‐binding protein‐mediated histone acetylation.31 The expression of CASC9 was increased in ovarian cancer tissues and cells and an enhanced level predicted an unfavorable prognosis in ovarian cancer patients. This evidence concerns the gene PDCD4 and esophageal squamous cell carcinoma.