[Silencing of tumor metastasis suppressor gene 1 promotes invasion of prostate cancer cell in vitro and its molecular mechanisms].

ABSTRACT

OBJECTIVE: To explore the effect of small interference RNA (siRNA) targeting homosapiens longevity assurance homologue 2(LASS2, or TMSG1) on the invasion of PC-3M-2B4 (a variant subline of human prostate carcinoma cell line PC-3M with low metastatic potential) and its molecular mechanisms. METHODS: PC-3M-2B4 cells were transfected with siRNA by using lipofectamine 2000. The expression of LASS2 mRNA and protein was detected after transfection by real-time fluorogentic quantitative PCR (RFQ-PCR) and Western blot to screen the effective siRNA fragment. The V-ATPase activity of PC-3M-2B4 cells was detected by V-ATPase activity assay kit. The concentration of extracellular hydrogen ion was measured by pH-sensitive fluorescence probe bis-carboxyethyl-carboxyfluorescein (BCECF). The matrix metalloproteinase-2 (MMP-2) protein in the supernatant and cells was analyzed by Western blot. The activity of MMP-2 was examined by Gelatin zymography. Furthermore, the migration and invasion of cells were evaluated by in vitro wound migration assay and invasion assay. RESULTS: RFQ-PCR and Western blot revealed dramatic reduction (84.5% and 60% ) in the levels of LASS2 mRNA and protein after transfection of siRNA-2 in PC-3M-2B4 cells. The V-ATPases activity and extracellular hydrogen ion concentration were significantly increased in PC-3M-2B4 cells transfected with the siRNA-2 compared with other control groups (P<0.05); There were no differences in the expression and secretion of MMP-2 protein between LASS2-siRNA treated cells and other control groups. However, the activity of MMP-2 was up-regulated in LASS2-siRNA treated cells compared with other control groups( P<0.05); and the capacity for migration and invasion in LASS2-siRNA treated cells was significantly higher than in other control groups (P<0.05). CONCLUSION: Silencing of LASS2 can promote invasion of prostate cancer cells in vitro through the increase of the V-ATPases activity, extracellular hydrogen ion concentration and in turn the activation of secreted MMP-2, indicating that LASS2 is a novel tumor metastasis suppressor gene.