Objective:To investigated the expression and localization of the long non-coding RNA(lncRNA)STAG3L5P in oral squamous cell carcinoma(OSCC)cells and its effects on OSCC cell proliferation and migration.Methods:STAG3L5P expression in HNSC and OSCC was ana-lyzed online using gene expression profiling interactive analysis 2(GEPIA2)and the University of California Santa Cruz Xena(UCSC Xena)database,respectively.STAG3L5P expression in OSCC cell lines was detected using real-time fluorescence quantitative PCR(qPCR).Nuclear-cytoplasmic RNA fractionation assays were carried out to pinpoint the location of STAG3L5P.Cell counting kit-8(CCK-8)and Transwell migra-tion assays were used to assess OSCC cell proliferation and migration changes.The effect of STAG3L5P overexpression on epithelial-mesen-chymal transition(EMT)related gene expression was detected by qPCR and Western blot.The effect of STAG3L5P overexpression on PI3K/AKT pathway activity was also assessed by Western blot.Results:STAG3L5P was highly expressed in OSCC,and its expression correl-ated significantly with histological grade.STAG3L5P expression was significantly higher in OSCC cell lines than in normal cells.The level of cytoplasmic STAG3L5P in OSCC cells was significantly higher than that in the nucleus.The proliferation and migration capacity of OSCC cells overexpressing STAG3L5P were significantly enhanced compared to negative control OSCC cells.N-cadherin and vimentin mRNA and protein levels were significantly increased by STAG3L5P overexpression,while E-cadherin protein expression was decreased.Overexpression of STAG3L5P also increased activity of p-PI3K and p-AKT.Conclusions:STAG3L5P is up-regulated in OSCC,and STAG3L5P overexpression can promote OSCC cell proliferation and migration.This effect may be related to activation of the PI3K/AKT pathway,thus promoting EMT.