Epigenetically silenced LINC02381 functions as a tumor suppressor by regulating PI3K-Akt signaling pathway

Recent advances have revealed that lncRNAs play important roles in tumorigenesis. However, only a small number of functional lncRNAs have been well characterized, particularly in colorectal cancer. Therefore, more extensive studies are needed to identify and characterize these lncRNAs to better understand cancer progression. In the present study, using available RNA-seq data, we found that LINC02381 (NR_026656.1) differentially expresses in CRC tissues compared to normal pairs. Consistently, RT-qPCR results showed that LINC02381 was down regulated in CRC tissues and also in different cancerous cell lines. CRC cells treatment with de-methylating and chemotherapy agents indicated that DNA methylation of LINC02381 may be responsible for the transcriptional silencing of LINC02381 in colorectal cancer cells. Then, the functional changes of the cells in response to LINC02381 alteration were assessed and the data indicated that LINC02381 up-regulation suppressed cell viability and proliferation while increasing the apoptosis in CRC-originated cell lines. Mechanistically, LINC02381 overexpression was increased PTEN protein levels but decreased phospho-Akt levels. Finally, we proposed a hypothesized model for PI3K signaling regulation by LINC02381. Altogether, the result of this study suggests that LINC02381 might have suppressive effects on human colorectal cancer tumorigenesis partly by regulating PI3K signaling pathway.