Objective:To explore the expression of transmembrane protein 9(TMEM9)as an oncogene in prostate cancer(PCa),and to examine its effect on the proliferation and invasion of PCa cells as well as on the Wnt/β-catenin signaling pathway and autophagy of PCa cells by intervening with its expression.Methods:The Cancer Genome Atlas was used for pan-cancer analysis of TMEM9 expres-sion levels in different tumors,and TMEM9 protein and messenger ribonucleic acid(mRNA)levels in clinical PCa and prostatic hyper-plasia specimens were analyzed.Real-time quantitative polymerase chain reaction and western blotting were used to analyze TMEM9 expression levels in different PCa cell lines.Cell counting,terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL),and Transwell assay were used to analyze cell proliferation,apoptosis,and PCa cell invasion,respectively.Subcutaneous tu-morigenesis in nude mice was used to analyze tumor proliferation in vivo.Western blotting was used to analyze the expression of autophagy-related pathway proteins,and transmission electron microscopy and immunofluorescence colocalization were used to deter-mine the colocalization of autophagosomes and lysosomes.Results:TMEM9 was highly expressed in PCa.The mRNA and protein ex-pression levels of TMEM9 were higher in PCa tissues than in prostatic hyperplasia tissues.The expression of TMEM9 was highest in PC3 cells(human PCa cells)(t=17.150,P<0.01).In TMEM9-knocked down PC3 cells,the proliferation(t=3.165,P<0.05)and inva-sion(F=76.620,P<0.01)significantly decreased,and apoptosis(t=13.530,P=0.010)significantly increased.After knockdown of TMEM9,the volume(F=1 699.000,P<0.01)and weight(t=9.057,P<0.01)of subcutaneous tumors in nude mice were reduced,and tu-mor growth was inhibited.TMEM9 regulated the Wnt/β-catenin signaling pathway and inhibited the AKT-mTOR signaling pathway to promote autophagy in PCa cells.Conclusion:TMEM9 inhibits the AKT-mTOR signaling pathway and promotes the proliferation and invasion of PCa cells through autophagy.