MicroRNA‑199a‑5p suppresses cell proliferation, migration and invasion by targeting ITGA3 in colorectal cancer.

As a member of the integrin family, integrin α3β1 (ITGA3) has been linked to intercellular communication and serves an important role in the signaling among cells and the extracellular matrix. MicroRNA (miR)‑199a‑5p has been demonstrated to be related to the pathogenesis and progression of multiple malignant diseases. However, the biological functions of miR‑199a‑5p and ITGA3 in colorectal cancer (CRC) have rarely been reported. The aim of the present study was to explore the roles of miR‑199a‑5p and ITGA3 in CRC. Immunohistochemistry staining and western blotting were applied to detect the protein expression of ITGA3 in CRC tissues and cells. Reverse transcription‑quantitative PCR was performed to investigate the expression of miR‑199a‑5p and ITGA3 mRNA. HCT‑116 cells were transfected with miR‑199a‑5p mimics, mimics control, short hairpin RNA targeting ITGA3, or pcDNA‑ITGA3 for the functional experiments. Dual luciferase reporter assay was applied to confirm whether miR‑199a‑5p targeted the 3' untranslated region (3'UTR) of ITGA3. The MTT, Transwell and wound healing assays were used to evaluate the proliferation, invasion and migration of CRC cells. Immunofluorescence assay was used to monitor the epithelial‑mesenchymal transition (EMT) biomarker expression. The results demonstrated downregulation of miR‑199a‑5p and upregulation of ITGA3 in CRC tissues and cell lines. miR‑199a‑5p mimics and knockdown of ITGA3 suppressed the proliferation, invasion and migration of CRC cells. Bioinformatics analysis and luciferase reporter assay indicated that miR‑199a‑5p targeted the 3'UTR of the ITGA3 transcript, and overexpression of ITGA3 reversed the tumor‑suppressive effects of miR‑199a‑5p elevation. In addition, the immunofluorescence assay suggested that miR‑199a‑5p mimics suppressed the EMT of CRC cells, whereas the overexpression of ITGA3 restored this effect. In conclusion, miR‑199a‑5p may act as a tumor suppressor by targeting and negatively regulating ITGA3 in CRC.