SMAD6, positively regulated by the DNM3OS-miR-134-5p axis, confers promoting effects to cell proliferation, migration and EMT process in retinoblastoma

Hui Wang,Xiang Ji

doi:10.1186/s12935-020-1103-8

Abstract

BackgroundRetinoblastoma (RB) is acknowledged to be the commonest intraocular malignancy in infants and children and the outcome of RB patients is unfavorable due to limited early diagnosis and effective therapy. SMAD family member 6 (SMAD6) has been reported in the initiation and progression of human cancers by acting as a biological participant. However, the role of SMAD6 in RB has not been illustrated yet.MethodsThe expression of SMAD6 mRNA, miR-134-5p and DNM3OS was measured by RT-qPCR. SMAD6 protein levels were measured by western blot. The effects of SMAD6 depletion on RB cells were analyzed using CCK-8 and transwell assays. The key proteins related to epithelial-mesenchymal transition (EMT) was determined by western blot. The localization of DNM3OS was detected by nuclear/cytoplasmic assay. In addition, the direct interaction between miR-134-5p and SMAD6 or DNM3OS was confirmed with the application of dual-luciferase reporter assay.ResultsSMAD6 was upregulated in RB tissue samples and cell lines, and silencing SMAD6 suppressed cell proliferation, migration and EMT in RB. Mechanically, SMAD6 was positively regulated by lncRNA DNM3OS through competitively interacting with miR-134-5p. DNM3OS contributed to RB progression by SMAD6-mediated manner.ConclusionsThis research unmasked a novel DNM3OS/miR-134-5p/SMAD6 pathway in RB, which might make contribution to treatment of RB.

Highlights

Retinoblastoma (RB) is acknowledged to be the commonest intraocular malignancy in infants and children and the outcome of RB patients is unfavorable due to limited early diagnosis and effective therapy
Since the sh-SMAD family member 6 (SMAD6)-1 and sh-SMAD6-2 groups were more efficient in reducing SMAD6 transcript, sh-SMAD6-1 and sh-SMAD6-2 were used in the subsequent loss-of-function assays
Cell proliferation was measured by CCK-8 assay and it was demonstrated that the cell proliferation was obviously decreased after SMAD6 depletion (Fig. 1f )

Summary

Introduction

Retinoblastoma (RB) is acknowledged to be the commonest intraocular malignancy in infants and children and the outcome of RB patients is unfavorable due to limited early diagnosis and effective therapy. SMAD family member 6 (SMAD6) has been reported in the initiation and progression of human cancers by acting as a biological participant. RB patients, especially those in the developing countries, could not be diagnosed in the early stage or receive effective treatment and present to have unfavorable prognosis [3]. Intracellular SMAD proteins play a pivotal role in transcriptional activation of downstream genes synergistically with transcription factors via mediating the canonical TGF-β signaling pathway. SMAD6 has been reported to participate in initiation and progression of many human cancers. SMAD6 recovers the growth inhibition induced by TGF-beta in COLO-357

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