| Prostate cancer is a leading cause of cancer-related deaths in the Western countries, and the incidence and mortality rates of prostate cancer have increased markedly. Since the current methods of treatment effect is not ideal, it is imperative to seek seek new treatment modalities. Cancer is a kind of genetic disease, so the gene therapy as a novel tumor therapy has been paid more attention.Human plasma membrane-associated sialidase (Neu3) is unique in specifically hydrolyzing gangliosides and in its subcellular localization of plasma membranes. Neu3 plays crucial roles in the regulation of cell surface functions. Neu3 is markedly upregulated in human colon cancer and breast cancer, leading to apoptosis suppression. The Neu3 expression level and the tumor grade were positive correlations. The researchers considered it as tumor marker. We found that Neu3 was overexpressed in prostrate cancer. RNAi technique selectively inhibited cancer gene over-expression, so as to achieve the purpose of cancer treatment. Taken together, the present findings suggest that Neu3 is a promising molecular target for the therapy of prostate cancer.Metastasis is not only an important feature of tumor, but also causes tumor relapse. And multi-stage, many molecules involved in the metastic process. Interactions of tumor cell and extracellular matrix change the extracellular matrix composition and content. Matrix metalloproteinases (MMPs) secreted by Tumor cells degrad extracellular matrix and regulat cell adhesion. Considerable research has proved that MMPs play an important role in disease occurrence and development, especially in tumor invasion and metastasis. Therefore, MMPs become an important indicator for the detection of tumor cell invasion and migration.Proliferating cell nuclear antigen (PCNA) is closely related to cell DNA synthesis and a good tumor markers. It also has a relationship with tumor grade, tumor stage and chemotherapy sensitivity. Its mark index and the malignancy elevates obviously along with organization's cancer process. Enhua Wang in lung adenocarcinoma of the studies in analysis of PCNA labelling index: high differentiation was lowest, differentiated group was slightly higher, low differentiation was highest, which found that PCNA labeling index and the grade of the tumor was positively related to. Therefore, we choose it as the evaluation of Neu3 siRNA in vivo role of antitumor is an important indicator. We knock down Neu3 gene by gene silence technique. Neu3 siRNA inhibited cell proliferation and promote apoptosis, inhibit cell migration in prostrate cancer cell line. Experimental results have the same trend both in vivo and in vitro. After synthesizing each experimental result, we think that si-Neu3 possibly become a new method of treating the prostate gland cancer's one new method.Objective:Study of the effect and its mechanism of Neu3 siRNA on prostate cancer cell growth and metastasis in vivo.Methods:The prostate cancer cell lines PC-3M were transfected with plasmids pGCsi-Neu3. We used a MTT assay to monitor the growth of transfected PGCsi-Neu3 recombinant plasmid cells. A further analysis of the effect of PGCsi-Neu3 recombinant plasmid on apoptosis is by FACS. Some genes in apoptotic pathway were detected through RT-PCR and western bloting. Wound assay and Transwel assay were tested the capability of invasion of cell. Male BALB/c nude mice, aged 6 weeks, were purchased from the Beijing Institute for Experimental Animals (Beijing, China). To analyze the effects of Neu3 on tumors, a tumor of 2×2×2 mm3 was implanted in the lateral lobes of the prostate gland of the nude mice. After 5 days, the mice were randomly split into four experimental groups (five mice/group). The mice were treated at 5 and 25 days by intranasal administration as follows: (a) mock (PBS buffer alone); (b) AS (Attenuated Salmonella); (c) pGCsi-Scramble (attenuated Salmonella carrying pGCsi-Scramble); or (d) pGCsi-Neu3 (attenuated Salmonella carrying pGCsi-Neu3-3). After 45 days, the mice were injected with 3.7–5.5×104 Bq of 99Tc-MDP and evaluated by SPECT/CT with double large-field-of-view gamma cameras (E.CAM; Siemens AG, Erlangen, Germany) to determine the bone metastases. The mice were then killed, and the spine and some of the tumor blocks were fixed in formalin for HE staining. In addition, the tumor blocks were evaluated by RT-PCR, western blotting and immunohistochemical analyses.Results:1. Neu3 was overexpressed in prostrate cancer cell lines and tissues.2. Neu3 siRNA inhibited cell growth and invasion, promoted cell apoptosis in vitro.3. Neu3 siRNA inhibited cell growth and invasion, promoted cell apoptosis in vivoConclusion:Neu3 siRNA inhibit cell growth and invasion; promote cell apoptosis in vivo and in vitro...
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