Fig 2: Microcystin (MC)-RR inhibits the expression of hypoxia inducible factor 1 subunit alpha (HIF-1α) and alters the level of matrix metalloproteinases (MMPs). Unilateral ureteral obstruction (UUO) mice and the cultured NRK-49F cells were treated as described in Figure 2 and Figure 4, respectively. (A,B) Expression of HIF-1α protein in the kidney tissues was detected by western blot. (C) Level of HIF-1α in NRK-49F cells was determined by western blot. (D,E) Expression levels of MMP-7, MMP-9, and MMP-13 in the kidney tissues of UUO mice were analyzed by western blot. (F) Deposition of collagen and elastic fibers in the kidney tissues of UUO mice with MC-RR treatment was evaluated by Sirius Red staining and Van Gieson staining (scale bar: 40 μm). *p < 0.05, **p < 0.01 determined by one-way ANOVA with S–N–K post hoc analysis, n = 5.

Fig 3: Metalloproteases in the brain of blast-exposed rats. Enriched brain vascular fractions were prepared from control and blast-exposed rats at 6 weeks post-exposure. Protein extracts (20 µg) from the enriched vascular fractions were analyzed by gelatin zymography. Panel a shows vascular upregulation of gelatinase activity associated with MMP-2, MMP-9 and their precursor proteins in the blast-exposed animal (B) as compared to control (C). Panels b, c show a brain arterial cross-section from a blast-exposed rat stained with antibodies against α-SMA (b, green) and MMP-9 (c, red). Panel d shows MMP-9 expression (green) in brain arterial smooth muscle of a blast-exposed rat at 13 months post-exposure. Panel e showns the same vessel in d stained with collagen IV (red). Brain sections of blast-exposed animals were stained with anti-rat IgG (red) and counterstained with DAPI (blue) f, g. Leakage of IgG could be seen in perivascular areas within the corpus callosum f or the entorhinal cortex g. Scale bars, 20 µm b, c 10 µm d, e 100 µm f; 300 µm g

Fig 4: MMP-9 or Madcam1 silencing decreases pulmonary metastasis of melanoma cells. Representative macroscopic and H&E images of mouse lungs colonized by metastatic B16-F10 melanoma cells. Scale bar = 20 μm. Quantification of metastatic foci (mean ± SD, n = 5) for each experimental condition is shown. Data are represented as mean ± SD. *p<0.05, **p<0.01, compared with shRNA control B16-F10 cells inoculated in TRIM59-CKO mice.

Fig 5: RA Inhibits Hepatoma Cell Invasion. Moreover, we detected the expression of MMP-2 and MMP-9 by western blot. RA dose-dependently inhibited the expression of MMP-2 and MMP-9 in HepG2 cells. Compared with the control group, the expression of MMP-2 in HepG2 cells was decreased by 20.0%, 40.7%, and 62.7%, and that of MMP-9 was decreased by 19.9%, 43.7%, and 70%, after treatment with 100, 200, and 400 µM for 24 h, respectively. These results suggested that RA inhibited hepatoma cell invasion and migration by reducing the expression of MMPs, thereby providing pathways for the invasion and metastasis of hepatoma cells