Effects of sodium nitrite on invasion of hepatoma SMMC-7721 cells
亚硝酸钠对人肝癌SMMC-7721细胞侵袭能力的影响

The aim of this study was to investigate the effect of sodium nitrite on the invasion of human hepatoma cell line SMMC-7721.The cell supernatants were collected from SMMC-7721 cells treated with 0.25 mmol.L-1 NaNO2 for 48 h.The tumor cell invasion was investigated with matrigel-coated transwell chamber assay.The change of cytoskeleton was observed by staining with Coomassie blue or immunofluorescence.The expression of matrix metalloproteinases (MMPs) protein in SMMC-7721 cells was detected by western blot.After treating SMMC-7721 cells with 0.25 mmol · L-1 NaNO2 for 48 h, the matrigel-coated invasion chamber assay was conducted.The results showed that the number of migrated cells was 211.5±17.6, and that of the control group was 176.3±15.5, indicating that NaNO2 could significantly increase cell migration (p<0.05).More cells invaded the ECM-coated filter in the group of serum-free media mixed with cell supernatants (165.12±7.90, p<0.05), compared with those in the serum-free, media-only group (negative control group, 30.32±11.00).The number of migrated cells in the group of media containing 10% fetal bovine serum (FBS) and cell supernatants (186.73±9.41) were also higher than those in the group of 10% FBS only (positive control, 170.54±9.60, p<0.05).After treatment with 0.25 mmol · L-1 NaNO2 for 48 h, the cellular cytoskeleton F-actin fibers distributing in the perimeter aggregated into intermediate filaments (stress fiber) and elongated along the vertical axis, resulting in elongation of the cellular body, the polymerization of tubulin and the over-expression of MMP-2 and MMP-9 protein.The results demonstrated that NaNO2 could induce cytoskeletal rearrangement and promote the capability of invasion in SMMC-7721 cells.