Long noncoding RNA LINC00165-induced by STAT3 exerts oncogenic properties via interaction with Polycomb Repressive Complex 2 to promote EMT in gastric cancer.

Long non-coding RNAs (lncRNAs) are a crucial member of the non-coding RNA family, and increasing evidence demonstrates that lncRNAs participate in the initiation and progression of cancers. Our study aimed to explore the role of the lncRNA LINC00165 in gastric cancer (GC) development. In the present study, our results showed that LINC00165 was upregulated in GC tissues and cell lines and high expression of LINC00165 was correlated with tumor-node-metastasis stage, invasion depth, and overall survival of GC patients. Functional assays showed that LINC00165 knockdown inhibited the proliferation, migration and invasion of GC cells and LINC00165 overexpression stimulated their proliferation, migration and invasion. Online transcription factor binding site prediction analysis showed that there were STAT3 binding sites in the LINC00165 promoter region. Furthermore, luciferase reporter and chromatin immunoprecipitation assays provided evidence that STAT3 could bind directly to the region between -547 bp to -537 bp (ATGTTGGGAAA) of LINC00165 promoter and activate its transcription. Then GC cells were partitioned into nuclear and cytoplasmic fractions and we found that LINC00165 was localized preferentially to the nucleus. Mechanistically, we revealed that LINC00165 functioned as a scaffold for interaction with Polycomb Repressive Complex 2 to promote the epithelial-mesenchymal transition in GC cells. Taken together, our study revealed that LINC00165 was involved in the progression and poor prognosis of GC as an oncogenic role. Therefore, LINC00165 might become a new potential target for GC chemotherapy and further predict prognosis of patients.