LINC02381 suppresses cell proliferation and promotes apoptosis via attenuating IGF1R/PI3K/AKT signaling pathway in breast cancer

Identification of the genes and genetic networks involved in breast cancer development is a major need for prevention and therapy. LINC02381 (lncRNA) has already been introduced as a tumor suppressor in colorectal and gastric cancers. Here, we intended to investigate its potential functional effects on breast cancer. In the analysis performed on RNA-Seq and microarray data, the LINC02381 lncRNA was found to be significantly downregulated in the breast tumors and associated with poor survival of the patients. Then, the differential expression of LINC02381 was confirmed in breast tumor tissues and cancer cell lines using RT-qPCR. Overexpression of LINC02381 resulted in reduced IGF1R and p-AKT expression levels which indicates decreased PI3K pathway activity, detected by RT-qPCR and western blotting. At the cellular level, LINC02381 overexpression was followed by a decreased proliferation rate of transfected breast cell lines, detected by PI flow cytometry, RT-qPCR, colony formation, and MTT assays. Consistently, the results of Annexin-V/PI flow cytometry, RT-qPCR, caspase3/7 activity, and AO/EB-H33342/PI dual staining revealed that LINC02381 overexpression induced apoptosis and cell death. The reduced migration rate of these cells was also verified through wound healing assay and RT-qPCR against the EMT-involved genes. Our data show that LINC02381 exerts its tumor suppressor effect at least partly through attenuation of the IGF1R/PI3K/AKT signaling pathway, which originated from IGF1R downregulation.