Pinitol Suppresses Tumor Necrosis Factor-α-Induced Invasion of Prostate Cancer LNCaP Cells by Inhibiting Nuclear Factor-κB-Mediated Matrix Metalloproteinase-9 Expression

Purpose: To investigate the mechanism by which pinitol inhibits tumor necrosis factor-α (TNF-α)- induced expression of matrix metalloproteinase-9 (MMP-9) and invasion of prostate cancer LNCaP cells.
Methods: Reverse transcription-polymerase chain reaction (RT-PCR) together with Western blot analysis was used to analyze the expression of MMP-9 and nuclear factor-κB (NF-κB) subunits, p65 and p50, in TNF-α-treated LNCaP cells, while 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, flow cytometry, and DNA fragmentation were used to evaluate cell viability and apoptosis. MMP-9 activity and invasion were measured by gelatin zymography and matrigel invasion assay, respectively. DNA-binding activity of NF-κB and AP-1 was determined by electrophoretic mobility shift assay and luciferase activity.
Results: MMP-9 activity significantly increased in response to TNF-α; however, pinitol reduced TNF-α- induced MMP-9 activity without cytotoxicity. Matrigel invasion assay showed that pinitol reduced TNF-α- induced invasion of prostate cancer LNCaP cells. Further, it downregulated the expression of MMP-9 gene induced by TNF-α-treatment. Pinitol suppressed TNF-α-induced NF-κB activity by suppressing nuclear translocation of the NF-κB subunits, p65 and p50.
Conclusion: The results indicate that pinitol is a potential anti-invasive agent and acts by suppressing TNFα-induced cancer cell invasion and specifically inhibiting NF-κB as well as downstream target genes such as MMPα9.

Keywords
Pinitol; Matrix metalloproteinase-9; Cell invasion; Nuclear factor-κB; Nuclear translocation