LncRNA MEG8 通过靶向 miR-15a-5p 调控 MICA/B 介导结直肠癌细胞免疫逃逸.

Objective: To explore mechanism of long non-coding RNA maternally expressed gene 8 (LncRNA MEG8) mediates immune escape in colorectal cancer (CRC) cells by regulating MICA/B via targeting miR-15a-5p. Methods: RT-qPCR and Western blot were used to detect expressions of MEG8, miR-15a-5p, MICA, MICB, NKG2D protein in CRC tissue and cell lines; dual luciferase experiment was used to verify regulatory relationship of MEG8 on miR-15a-5p; NC, MEG8, miR-NC and miR-15a-5p were respectively or co-transfected into SW480 and SW620 cells by liposome transfection, and recorded as NC group, MEG8 group, MEG8+miR-NC group, MEG8+miR-15a-5p group; NK cells were cocultured with SW480 and SW620 cells respectively; ELISA was used to detect TNF-α and IFN-γ levels in coculture medium; CCK-8, EdU staining, Transwell assay were used to detect cell proliferation, migration and invasion ability; RT-qPCR and Western blot were used to detect MEG8, miR-15a-5p, MICA, MICB, NKG2D protein levels in cells. Results: Compared with adjacent cancer tissues or normal colon epithelial cells, MEG8, MICA, MICB, NKG2D mRNA and protein levels in CRC tissues and cell lines were decreased, while miR-15a-5p level was increased (P<0.05). MEG8 targeting regulated miR-15a-5p. In cocultivation system, compared with NC group, MICA, MICB, NKG2D protein levels, TNF-α, IFN-γ levels in cocultured supernatant in MEG8 group were significantly increased, after 1 d, 2 d, and 3 d of cell culture, OD value, EdU positive rate, number of migrating and invading cells were significantly decreased (P<0.05); overexpression of miR-15a-5p could partially reverse effects of overexpression of MEG8 on MICA, MICB, NKG2D, TNF-α, IFN-γ levels in cells, proliferation, invasion and metastasis ability( P<0.05). Conclusion: MEG8 promotes NK cell activity and inhibits CRC cell immune escape by regulating MICA and MICB expressions via targeting miR-15a-5p. [ABSTRACT FROM AUTHOR]