Purpose: Long non-coding RNA (lncRNA) XIST has been shown to be involved in the immune escape of breast cancer, but it is unclear whether it is involved in the immune escape of lung cancer, so it will be discussed in this study.
Methods: XIST and miR-34a-5p expression in lung cancer tissues and cells were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The targeting relationship between miR-34a-5p and XIST/programmed cell death receptor ligand 1 (PDL1) was predicted by bioinformatics website and verified by dual-luciferase report experiment. After co-transfection with XIST specific short hairpin RNA (sh-XIST) and miR-34a-5p inhibitors, the changes in PDL1 expression, and cell biological behavior were detected by qRT-PCR, cell counting kit 8, flow cytometry, and Transwell experiments. Similarly, after co-transfection of PDL1 specific small interfering RNA (siPDL1) and miR-34a-5p inhibitors, the changes in cell biological behavior were detected again. After CD8+ T cells were co-cultured with lung cancer cells transfected with sh-XIST and miR-34a-5p inhibitors, the expression of cytokines and immunosuppressive molecules was detected by western blot and enzyme-linked immunosorbent assay (ELISA).
Results: XIST was up-regulated in lung cancer tissues, while miR-34a-5p was the opposite. XIST up-regulated the expression of PDL1 by targeting miR-34a-5p, thereby affecting the viability, apoptosis, migration, and invasion of lung cancer cells. In the co-culture system, XIST targeted miR-34a-5p to inhibit cytokines secretion and promote the expression of immunosuppressive molecules.
Conclusions: XIST/miR-34a-5p/PDL1 axis was involved in the malignant biological behavior of lung cancer cells and the immune function of CD8+ T cells.
Keywords: Lung cancer; immune checkpoint; long non-coding RNA XIST; miR-34a-5p; programmed cell death receptor ligand 1.