Abstract: Objective To explore the effect of aldehyde dehydrogenases 1A1 (ALDH1A1) on biological behavior of gastric cancer cell MKN-45 through wingless protein (Wnt) signaling pathway.Methods MKN-45 cells were transferred with the control and sh-RNA-ALDH1A1.The expression of ALDH1A1 in MK-45 cells was determined with reveres transcriptase-PCR (RT-PCR) and Western blot.The cell viability was detected with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.The cell migration and invasion were detected with transwell method.The expressions of matrix metalloproteinase 2 (MMP2),matrix metalloproteinase 9 (MMP9),Wnt1,Wnt5a,and β-catenin were detected with Western blot.Results Compared with those of the control group,the ALDH1A1 transfected cells showed significantly down-regulated expressions of ALDH1A1 protein (0.89±0.09 vs. 0.09±0.01) and mRNA (0.48±0.05 vs. 0.08±0.01),decreased cell viability (0.73±0.07 vs. 0.40±0.04),inhibited cell migration (98.86±9.03 vs. 39.78±3.24) and invasion (90.52±9.14 vs. 42.53±4.25),and down-regulated expressions of MMP2 (0.49±0.04 vs. 0.10±0.01),MMP9 (0.95±0.09 vs. 0.10±0.01),Wnt1 (1.29±0.12 vs. 0.28±0.03),Wnt5a (0.52±0.04 vs. 0.12±0.01),and β-catenin (0.56±0.05 vs. 0.19±0.02) (P<0.01 for all).Conclusion ALDH1A1 silence could decrease cell viability and inhibit cell migration and invasion via regulation of Wnt signal pathway in MK-45 cells.