The LINC00319 binding to STAT3 promotes the cell proliferation, migration, invasion and EMT process in oral squamous cell carcinoma.

Background: Long non-coding RNA LINC00319 has been implicated in the progression of various cancers, including oral squamous cell carcinoma (OSCC). While our previous work has revealed some aspects of LINC00319's role in OSCC, including its upregulation and involvement in a competing endogenous RNA (ceRNA) mechanism, the full extent of its functions and regulatory mechanisms in OSCC progression remain to be fully elucidated.

Objective: This study aimed to investigate the function of LINC00319 in OSCC and its potential interaction with the STAT3 signaling pathway, thus uncovering novel regulatory mechanisms and therapeutic targets.

Methods: Bioinformatics analysis was performed using TCGA data to evaluate LINC00319 expression in OSCC tissues and its correlation with STAT3 signaling. The direct binding between LINC00319 and STAT3 was examined by RNA pull-down, FISH, and RIP assays. Functional experiments, including CCK-8, transwell migration and invasion assays, and western blot analysis of EMT markers and STAT3 pathway activation, were conducted to assess the effects of LINC00319 on OSCC cell behaviors and its interaction with the STAT3 signaling pathway. In vivo xenograft models were established to validate the role of LINC00319 in tumor growth and STAT3 activation.

Results: LINC00319 expression was significantly upregulated in OSCC tissues compared to normal tissues, and high LINC00319 expression correlated with STAT3 signaling activation. Mechanistically, LINC00319 directly bound to STAT3 protein and promoted its phosphorylation at Tyr705. LINC00319 overexpression enhanced, while its knockdown suppressed, the proliferation, migration, invasion, and EMT of OSCC cells. These oncogenic effects were mediated through STAT3 activation and could be reversed by the STAT3 inhibitor stattic. In vivo experiments further confirmed that LINC00319 silencing inhibited tumor growth and STAT3 phosphorylation.

Conclusion: This study uncovers that LINC00319 promotes OSCC tumorigenesis by directly binding to and activating STAT3 signaling. These findings provide new insights into the regulatory mechanisms of STAT3 by long non-coding RNAs and highlight the potential of LINC00319 as a biomarker and therapeutic target in OSCC.