Abstract： Objective To investigate the expression of Bcl-2 associated athanogene 3 (BAG3) in cervical cancer tissues and cells and its role in epithelial mesenchymal transition (EMT) of cervical cancer.Methods (1) Cervical cancer samples were collected from September 2015 to March 2017 in the Qilu Hospital of Shandong University and Shangdong Provincial Hospital.While,50 normal tissues were collected from August 2015 to March 2017 in the Dezhou Municiple Hospital,which were obtained from patients with uterine mnyoma underwent hysterectomy and patients with cervical biopsy.Reverse transcription (RT)-PCR and western blot were used to detect the expression of BAG3 mRNA and protein,and their clinical significances were analyzed.(2) The expression of BAG3 mRNA and protein was detected using RT-PCR and western blot method in HeLa and SiHa cell lines and normal cervical epithelial cells.The experiment was divided into two groups,BAG3 small interfering RNA transfected group (st-BAG3) and the control group transfected with small interfering RNA (siRNA).Cell counting kit 8 (CCK-8) analysis was used to detect cell proliferation of two groups.Wound-healing and transwell assay were used to detect the migration and invasion ability of HeLa and SiHa cells.The xenograft model of cervical cancer in nude mice was used to observe the effect of BAG3 on tumor xenografts and the tumor-related biomarkers were tested by western blot.Results (1) The expression levels of BAG3 mRNA and protein in cervical carcinoma tissues were 1.20±0.15 and 1.10±0.16,which were significantly higher than that in normal cervical tissue,0.23± 0.04 and 0.29 ± 0.03 (both P＜0.01).The results showed that the expression levels of BAG3 mRNA and protein were significantly correlated with cervical carcinoma staging and lymph node metastasis (P＜0.05).However,its expression was not conrelated with the patient's age,pathological grade,and diameter of tumor (all P＞0.05).(2) Compared with normal cervical epithelial cells,the expression of BAG3 mRNA and protein levels in HeLa and SiHa cells were significantly increased (P＜0.01),the expression levels of BAG3 mRNA and protein in HeLa and SiHa cells transfected with si-BAG3 were significantly lower than that in control group (all P＜0.01).After post-transfected 72 hours,A value of HeLa and SiHa with transfection were significantly lower than those in control group [(0.88±0.08) vs (1.22±0.13),(0.92±0.09) vs (1.35±0.12);both P＜0.01].After post-transfected 24 hours,the migration level of HeLa and SiHa cells with transfection were significantly lower than those in the control group [(20.1±2.1)％ vs (58.6±5.6)％,and (21.1±2.1)％ vs (61.7± 5.4)％;both P＜0.01].The transmembrane cell number in HeLa and SiHa cells with transfection were 76± 11 and 71±8,which were significantly less than those in control group (131± 12 and 129± 14;both P＜0.01).After the inoculation into nude mice,tumor formation time of HeLa and SiHa cells with transfection were (9.5±0.5) and (10.5 ± 1.3) days,respectively,which were significantly longer than those in control group [(4.5±0.5) and (5.2± 1.1) days;both P＜0.05].Compared with those in the control group,the expression level of Slug,N-cadherin and matrix metalloproteinase-2 (MMP-2) protein in HeLa and SiHa cells with transfected in tumor tissues were significantly decreased (all P＜0.01),while the expression level of E-cadberin protein was significantly increased (P＜0.01).Conclusion BAG3 could be involved in the proliferation,migration and invasion of cervical cancer cells by affecting cervical cancer EMT,and BAG3 may be an effective target for the treatment of cervical cancer.