LINC00668 cooperated with HuR dependent upregulation of PKN2 to facilitate gastric cancer metastasis

In China, gastric cancer (GC) ranks first in the incidence of all malignant tumors. With high recurrence and distant metastasis, GC has caused considerable mortalities. LncRNA long intergenic non-protein-coding RNA 668 (LINC00668) has been reported to be upregulated in GC cells and predict poor prognosis of GC patients. However, the mechanism of LINC00668 has not been fully investigated in GC. This study aimed to investigate the role of LINC00668 in GC. We found that LINC00668 level was upregulated in GC tissue and cells and predicted poor prognosis. Functionally, LINC00668 knockdown suppressed GC cell migration and invasion. Additionally, LINC00668 knockdown inhibited epithelial to mesenchymal transition (EMT) process. PKN2 exerts similar effects with LINC00668 in GC cells. LINC00668 knockdown suppressed tumor growth and metastasis in vivo. Mechanistically, HuR was predicted to bind with LINC00668 and protein kinase N2 (PKN2). RNA pull-down assays validated the binding between HuR and LINC00668 (or PKN2). Moreover, either silencing of LINC00668 or HuR could decrease PKN2 mRNA stability or reduce PKN2 mRNA and protein levels. Furthermore, PKN2 expression was positively correlated with LINC00668 expression and HuR expression in GC tissues, and HuR expression was positively associated with LINC00668 expression in GC tissues. Finally, rescue assays confirmed that the suppressive effect of LINC00668 silencing on cell migration, invasion, and EMT process was reversed by PKN2 overexpression or HuR upregulation. In conclusion, LINC00668 cooperated with HuR-dependent upregulation of PKN2 to facilitate gastric cancer metastasis, which may provide a potential novel insight for GC treatment.