Shikonin-mediated up-regulation of miR-34a and miR-202 inhibits retinoblastoma proliferation.

Retinoblastoma (RB) is an ocular tumor that occurs mainly in children. The pathogenesis of RB is not well understood, and its treatment strategies are very limited. Shikonin is widely reported as an anti-tumor agent. However, its effect on RB is still unknown. MTT assay was performed to detect the proliferation ability of two RB cell lines, Y-79 and WERI-Rb-1, upon treatment with Shikonin. Colony formation assay was conducted to examine the clonogenic ability of Shikonin-treated cells. Real-time PCR and western blotting were performed for expression analysis of miRNAs and MYCN, respectively. Luciferase activity assay was conducted to test the inhibition mechanism of miR-34a and miR-202 on MYCN. Shikonin could effectively inhibit the proliferation of RB cells and upregulate the expressions of miR-34a and miR-202. MiR-34a and miR-202 could directly target the mRNA degradation of oncogene MYCN, and the inhibitory effect of Shikonin was largely weakened by restoring the MYCN protein expression. Shikonin-mediated up-regulation of miR-34a and miR-202 inhibits RB proliferation, partially mediated through MYCN.