Effect of long non-coding RNA long stress-induced noncoding transcript 5 on erlotinib resistance to lung cancer cells...

To explore the relationship between long non-coding RNA (lncRNA) long stress-induced noncoding transcript 5 (LSINCT5) and erotinib resistance to lung cancer cells and the potential mechanisms.

Human lung cancer cell line A549, H520, H358, H1299, SPCA1, and PC9 were collected and cultured. Epidermal growth factor receptor (EGFR) mutant lung cancer cell line PC9 was divided into a control group, a resistance group, a interference group I and II. The control group was treated with dimethylsulfoxide (DMSO) for 10 weeks and then was transfected with control target sequence expression vector. The resistant group was treated with erlotinib at gradient concentration (0.1, 0.2, 0.4, 0.8, and 1.6 μmol/L, respectively) for 2 weeks and then transfected with control target sequence expression vector. Interference group I and II were treated with erlotinib at gradient concentration (0.1, 0.2, 0.4, 0.8, and 1.6 μmol/L, respectively) for 2 weeks and then transfected with the shRNA targeting expression vectors 1 and 2. 50% inhibitory concentration (IC₅₀) of erlotinib was detected by cell counting kit-8 (CCK-8) assay. The mRNA expressions of LSINCT5, phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt) were measured by real-time PCR. The protein levels of PI3K, Akt, and phospho-Akt (p-Akt) were detected by Western blotting. The divergences of Akt and IgG binding to LSINCT5 were detected by RNA immunoprecipitation (RNA-IP) experiment.

The expression of LSINCT5 in PC9 cells was significantly higher than that in other lung cancer cell lines (all P<0.05). Compared with the control group, the IC₅₀ of erotinib and the expression of LSINCT5, PI3K, and Akt mRNA and protein in the resistance group were significantly higher (all P<0.05), and the IC₅₀ of erotinib and the expression of LSINCT5, Akt, and p-Akt in the interference group I and II were significantly lower (all P<0.05). Compared with IgG, LSINCT5 binding to Akt was increased significantly (P<0.05).

The expression of LSINCT5 is high in the erlotinib-resistant cells. Interference with LSINCT5 may inhibit the expression and activity of Akt and promote the cell sensitivity to erlotinib.