Abstract: Objective To explore the association of TMPRSS2-ERG (T-E) and MMP-9 gene on improve the invasiveness of prostate cancer. Methods Using FISH and RT-PCR to detect the expression of T-E and MMP-9 gene of prostate tissues, respectively. Including 40 metastatic prostate cancer cases, 20 localized prostate cancer cases, and 20 benign prostatic hyperplasia cases. Preparing siRNA that anti ERG and MMP-9 respectively, and transfecting them to two kinds of prostate cancer cells, then using Transwell detect the change of invasion ability of cells. Results The positive rates of T-E fusion gene and MMP-9 gene in 3 groups were gradually decreased (P＜0.05); they were positive associated with Gleason score (P＜0.05) and serum PSA level (P＜0.05) in metastatic prostate cancer group, respectively. In metastatic prostate cancer group, the expression of MMP-9 gene in T-E fusion gene positive patients is significantly higher than that in negative patients (P＜0.05), furthermore, the expression of the two genes was positively correlated with each other (r=0.875，P＜0.05). Downregulateing the expression of ERG gene can significantly reduce the invasion of VCaP cells (T-E fusion gene-positive), while reducing the expression of MMP-9 gene can only effectively Inhibit the invasion of LNCaP cells (T-E fusion gene-negative). Conclusion The expression of T-E fusion gene and MMP-9 gene were positively correlated with the invasiveness of prostate cancer, and T-E fusion gene can increase MMP-9 gene expression to improve the invasiveness. Both of them play a role in invasive prostate cancer, but MMP-9 may not be the target gene of T-E fusion gene.

Key words: prostate cancer, invasiveness, TMPRSS2-ERG, MMP-9, FISH