circ‑LRP6 contributes to osteosarcoma progression by regulating the miR‑141‑3p/HDAC4/HMGB1 axis.

Circular RNA‑lipoprotein receptor 6 (circ‑LRP6) serves a role in promoting the tumorigenesis of retinoblastoma, esophageal squamous cell cancer and oral squamous cell carcinoma; however, whether circ‑LRP6 demonstrates the same effect in osteosarcoma (OS) is yet to be fully elucidated. The present study aimed to analyze the expression, role and potential molecular mechanism of circ‑LRP6 in OS. The expression levels of circ‑LRP6, microRNA (miR)‑141‑3p, histone deacetylase 4 (HDAC4) and high mobility group protein 1 (HMGB1) were evaluated by reverse transcription-quantitative PCR in OS tissues and cell lines. Cell Counting Kit‑8, Transwell and Matrigel assays were conducted to evaluate cell proliferation, migration and invasion, respectively. Western blotting was also performed to determine HDAC4 and HMGB1 protein expression levels. Bioinformatics and dual‑luciferase reporter assays were used to predict and analyze the interactions between circ‑LRP6 and miR‑141‑3p, miR‑141‑3p and HDAC4, as well as between miR‑141‑3p and HMGB1. Additionally, RNA immunoprecipitation was performed to verify the association between circ‑LRP6 and miR‑141‑3p. The results confirmed that circ‑LRP6 was highly expressed in OS tissues and cell lines. In addition, circ‑LRP6 negatively regulated the expression of miR‑141‑3p and, in turn, miR‑141‑3p negatively regulated HDAC4 and HMGB1 expression. Functional assays revealed that circ‑LRP6 knockdown inhibited the proliferation, migration and invasion of OS cells, whereas the inhibition of miR‑141‑3p or the overexpression of either HDAC4 or HMGB1 partly reversed the inhibitory effect of circ‑LRP6 knockdown. In summary, the present study determined that circ‑LRP6 knockdown inhibited the proliferation, migration and invasion of OS cells by regulating the miR‑141‑3p/HDAC4/HMGB1 axis.