Seed-targeting anti-miR-21 inhibiting malignant progression of retinoblastoma and analysis of their phosphorylation signaling pathways

- We first reported the high level expression of miR-21 as oncomiR in retinoblastoma cells.
- Seed-targeting t-antimiR-21 had an inhibitory effect on malignant progression in retinoblastoma cells.
- The phosphorylation signal, down-regulated by t-anti-miR-21, was involved in 14 cancer-related pathways in retinoblastoma.

MiR-21 acts as a ubiquitous oncogene in major classes of human cancers and is a potential target for therapeutic intervention. However, the relative expression of miR-21 in retinoblastoma is poorly understood. Here we detected miR-21 expression in HXO-RB44 cell line human normal retinal tissues and retinoblastoma (Rb) tissue specimens, and studied its function using an 8-mer tiny seed-targeting anti-miR-21 (t-anti-miR-21). RT-PCR revealed that miR-21 was highly overexpressed in HXO-RB44 cells and Rb tissue specimens compared with normal human retinal tissues. The localization and transfection efficiency of t-anti-miR-21 and the cell cycle distribution were detected by confocal microscopy and flow cytometry. In addition, we found that t-anti-miR-21 led to a significant inhibition of retinoblastoma cell proliferation, migration and colony formation in vitro, with a similar effect to anti-miR-21. Anti-miR-21 down-regulated the miR-21 level, whereas both 8-mer t-anti-miR-21 and 15-mer m-anti-miR-21 had no impact on miR-21 expression levels. Finally, the phosphorylation signaling pathway, down-regulated by t-anti-miR-21, was integrated by KEGG assay, which elucidated the potential mechanisms of inhibition of miR-21 in retinoblastoma. Taken together, knockdown of miR-21 in the HXO-RB44 cell is capable of inhibiting cancer progression in retinoblastoma. Seed-targeting t-anti-miR-21 was a novel strategy for mir-21-based therapeutics and drug discovery.