ORF1p promotes proliferation and invasion of esophageal squamous cell carcinoma cells by regulating AJUBA expression

To investigate the effects of open reading frame 1 protein (ORF1p), encoded by long interspersed nuclear element-1 (LINE-1), on the proliferation, migration, and invasion of esophageal squamous cell carcinoma (ESCC) cells, and explore the underlying molecular mechanism.

① Western blotting was performed to compare the expression of ORF1p between normal esophageal squamous epithelial cells and ESCC cells. ② Immunohistochemistry (IHC) assay was used to examine ORF1p expression in ESCC tissues and paired normal tissues adjacent to tumor. ③ The effects of ORF1p knockdown and overexpression on malignant behaviors in ESCC cells were determined through functional assays. ④ Xenograft tumor model in nude mice was established to evaluate the impact of ORF1p on tumor growth in vivo. ⑤ Transcriptome sequencing combined with cell functional rescue experiments were conducted to identify downstream targets regulated by ORF1p.

① Western blot analysis demonstrated the expression of ORF1p was significantly higher in the ESCC cell lines than the normal esophageal squamous epithelial cells (P<0.05). ② IHC confirmed remarkable up-regulation of ORF1p in ESCC tissues than paired adjacent normal tissues (P<0.0001). ③ Functional assays and experiments on xenograft tumor models revealed that ORF1p substantially enhanced the proliferation, migration, and invasion of ESCC cells, as well as tumorigenic potential in vivo (P<0.05). ④ Functional rescue experiments showed that ORF1p facilitated the proliferation, migration, and invasion of ESCC cells by modulating AJUBA expression (P<0.05).

ORF1p is significantly up-regulated in ESCC and promotes the proliferation, migration, and invasion of ESCC cells by regulating AJUBA expression.