Long noncoding RNA GK‐IT1 promotes esophageal squamous cell carcinoma by regulating MAPK1 phosphorylation

BACKGROUND: Long noncoding RNAs (lncRNAs) are implicated in the oncogenesis and metastasis of multiple human cancers. Nonetheless, the precise molecular mechanisms underlying the oncogenic role of lncRNA in esophageal squamous cell carcinoma (ESCC) remains to be clarified. METHODS: The expression of GK intronic transcript 1 (GK‐IT1) was analyzed using ESCC RNA‐seq data from The Cancer Genome Atlas database. Quantitative real‐time PCR was used to measure the expression of GK‐IT1 in ESCC clinical samples and cells. The correlation between GK‐IT1 expression and clinicopathological variables was examined using chi‐squared tests. Kaplan–Meier survival and Cox regression analyses were employed to generate the survival curve and assess the prognostic value of GK‐IT1. Functional experiments were utilized to explore the role of GK‐IT1 in promoting cell migration, invasion, proliferation, and suppressing apoptosis and autophagy in ESCC. To understand the mechanism, an RNA pulldown assay, RNA immunoprecipitation, agarose gel electrophoresis, immunofluorescence, and co‐immunoprecipitation assays were used. RESULTS: In this study we identified an unreported lncRNA, termed GK‐IT1 that was aberrantly overexpressed in ESCC tissues and cells. GK‐IT1 was closely associated with advanced clinical stage, and it was an independent prognostic indicator of ESCC. Functional assays verified that GK‐IT1 significantly promoted ESCC proliferation, invasion, and migration, and suppressed ESCC apoptosis and autophagy. Furthermore, tumorigenesis experiments in nude mice indicated that GK‐IT1 promoted ESCC tumor growth and metastasis. Mechanistically, GK‐IT1 competitively bound to mitogen‐activated protein kinase 1 (MAPK1) to prevent the interaction between dual specificity phosphatase 6 (DUSP6) and MAPK1, thereby controlling the phosphorylation of MAPK1 and promoting ESCC progression. CONCLUSION: Our study revealed that GK‐IT1 competed with DUSP6 to attenuate the interaction between DUSP6 and MAPK1, leading to activation of the ERK/MAPK pathway, thereby promoting progression of ESCC. Our research indicated that GK‐IT1 served as a novel potential target for the diagnosis and treatment of ESCC.