Abstract

Matrix metalloproteinase (MMP)‑9 is a key enzyme responsible for extracellular matrix degradation and contributes to the progressive histological changes observed in lower respiratory tract infections. Integrin β1 and α‑tubulin are potential MMP‑9‑interacting proteins, and microRNA (miR)‑29b‑3p can regulate MMP‑9 expression. MMP‑9 is highly expressed in chronic rhinosinusitis with nasal polyps (CRSwNPs), regardless of its effects on miR‑29b‑3p, integrin β1 and α‑tubulin expression. In the present study, samples from 100 patients with CRSwNPs were examined via reverse transcription‑quantitative PCR to assess the mRNA expression of miR‑29b‑3p, and western blotting was performed to assess the protein expression of MMP‑2, MMP‑9, acetyl‑α‑tubulin, integrin β1 and tissue inhibitor of metalloproteinase 1 (TIMP‑1). A dual‑luciferase reporter assay was used to verify the direct binding of miR‑29b‑3p and MMP‑2/MMP‑9. Co‑immunoprecipitation (Co‑IP) and GST pull‑down assays showed that integrin β1 and α‑tubulin were MMP‑9‑interacting proteins. Cell viability, apoptosis and inflammatory cytokine levels were determined via a Cell Counting Kit‑8 assay, flow cytometry and ELISA, respectively. miR‑29b‑3p expression was found to be positively correlated with MMP‑2 and MMP‑9 expression. Whereas, TIMP‑1 expression was negatively correlated with MMP‑2 and MMP‑9 expression. The dual‑luciferase assay revealed that miR‑29b‑3p targeted the 3' untranslated region of MMP‑2/MMP‑9. The Co‑IP and GST pull‑down assays showed that MMP‑9 could directly bind to integrin β1 and indirectly bind to α‑tubulin. Finally, the overexpression of miR‑29b‑3p decreased the expression of MMP‑9 and increased the levels of acetyl‑α‑tubulin. By contrast, the knockdown of miR‑29b‑3p increased the expression of MMP‑9 and decreased the levels of acetyl‑α‑tubulin. Additionally, MMP‑9 expression was found to be negatively correlated with acetyl‑α‑tubulin expression. Of note, the expression of integrin β1 did not change