MicroRNA‑448 inhibits the progression of retinoblastoma by directly targeting ROCK1 and regulating PI3K/AKT signalling pathway.

Retinoblastoma (RB) is the most common primary intraocular malignancy during infancy and childhood worldwide. Numerous microRNAs (miRNAs) contribute to RB initiation and progression through the regulation of cell proliferation, cycle, apoptosis, migration, invasion and metastasis. Therefore, further investigation concerning the expression, roles and associated mechanisms of RB‑related miRNAs may be beneficial to develop novel strategies for patients with this malignancy. Recently, miRNA‑448 (miR‑448) has been reported to be aberrantly expressed and to play an important role in several types of human cancer. However, the expression patterns and biological roles of miR‑448 in RB have not been studied. The aim of the present study was to detect the expression levels of miR‑448 and investigate its functions in RB and its associated molecular mechanisms. In the present study, miR‑448 was significantly downregulated in RB tissues and cell lines. Upregulation of miR‑448 decreased cell proliferation and invasion and increased apoptosis in RB cells. Additionally, ρ‑associated coiled‑coil containing protein kinase 1 (ROCK1) was validated as a novel direct target gene of miR‑448 in RB. ROCK1 was overexpressed in RB tissues and inversely correlated with miR‑448 expression. Furthermore, ROCK1 silencing induced effects on the proliferation, invasion and apoptosis of RB cells similar to those observed following miR‑448 overexpression. Moreover, restoration of miR‑448 expression markedly reversed the effects of miR‑448 overexpression on RB cells, further supporting the hypothesis that ROCK1 is a direct functional target of miR‑448 in RB. Importantly, miR‑448 targeted ROCK1 to inhibit the activation of the PI3K/AKT signalling pathway in RB. These results demonstrated that miR‑448 may serve as a tumour suppressor in RB by directly targeting ROCK1 and regulating the PI3K/AKT signalling pathway, thereby suggesting that miR‑448 may be an effective therapeutic target for treating this aggressive cancer.