Retinol dehydrogenase 10 promotes metastasis of glioma cells via the transforming growth factor-β/SMAD signaling pathway

BACKGROUND: Glioma is the most common primary malignant tumor in the central nervous system. Because of the resistance of glioma to chemoradiotherapy and its aggressive growth, the survival rate of patients with glioma has not improved. This study aimed to disclose the effect of retinol dehydrogenase 10 (RDH10) on the migration and invasion of glioma cells, and to explore the potential mechanism. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the expression levels of RDH10 in healthy glial cells and glioma cells. Human glioma cell strains, U87 and U251, were infected with negative control or RDH10-interfering lentiviruses. RT-PCR and Western blotting were performed to determine the knockdown efficiency. Scratch and transwell assays were used to assess cell migration and invasion after RDH10 knockdown. Finally, changes in transforming growth factor-β (TGF-β)/SMAD signaling pathway-related expression were examined by Western blotting. Differences between groups were analyzed by one-way analysis of variance. RESULTS: RDH10 was highly expressed in glioma cells. Compared with the control group, RDH10 knockdown significantly reduced RDH10 messenger RNA and protein expression levels in U87 and U251 glioma cells (U87: 1.00 ± 0.08 vs. 0.22 ± 0.02, t = 16.55, P < 0.001; U251: 1.00 ± 0.17 vs. 0.39 ± 0.01, t = 6.30, P < 0.001). The scratch assay indicated that compared with the control group, RDH10 knockdown significantly inhibited the migration of glioma cells (U87: 1.00% ± 0.04% vs. 2.00% ± 0.25%, t = 6.08, P < 0.01; U251: 1.00% ± 0.11% vs. 2.48% ± 0.31%, t = 5.79, P < 0.01). Furthermore, RDH10 knockdown significantly inhibited the invasive capacity of glioma cells (U87: 97.30 ± 7.01 vs. 13.70 ± 0.58, t = 20.36, P < 0.001; U251: 96.20 ± 7.10 vs. 18.30 ± 2.08, t = 18.51, P < 0.001). Finally, Western blotting demonstrated that compared with the control group, downregulation of RDH10 significantly inhibited TGF-β expression, phosphorylated SMAD2, and phosphorylated SMAD3 (TGF-β: 1.00 ± 0.10 vs. 0.53 ± 0.06, t = 7.05, P < 0.01; phosphorylated SMAD2: 1.00 ± 0.20 vs. 0.42 ± 0.17, t = 4.01, P < 0.01; phosphorylated SMAD3: 1.00 ± 0.18 vs. 0.41 ± 0.12, t = 4.12, P < 0.01). CONCLUSION: RDH10 knockdown might inhibit metastasis of glioma cells via the TGF-β/SMAD signaling pathway.