SDF-1 chemokine signalling modulates the apoptotic responses to iron deprivation of clathrin-depleted DT40 cells

Expression patterns of iron regulatory proteins after intense light exposure in a cone-dominated retina

Iron is implicated in ocular diseases such as in age-related macular degeneration. Light is also considered as a pathological factor in this disease. Earlier, two studies reported the influence of constant light environment on the pattern of expressions of iron-handling proteins. Here, we aimed to see the influence of light in 12-h light-12-h dark (12L:12D) cycles on the expression of iron-handling proteins in chick retina. Chicks were exposed to 400 lx (control) and 5000 lx (experimental) light at 12L:12D cycles and sacrificed at variable timepoints. Retinal ferrous ion (Fe²⁺) level, ultrastructural changes, lipid peroxidation level, immunolocalization and expression patterns of iron-handling proteins were analysed after light exposure. Both total Fe²⁺ level (p = 0.0004) and lipid peroxidation (p = 0.002) significantly increased at 12-, 48- and 168-h timepoint (for Fe²⁺) and 48- and 168-h timepoint (for lipid peroxidation), and there were degenerative retinal changes after 168 h of light exposure. Intense light exposure led to an increase in the levels of transferrin and transferrin receptor-1 (at 168-h) and ferroportin-1, whereas the levels of ferritins, hephaestin, (at 24-, 48- and 168-h timepoint) and ceruloplasmin (at 168-h timepoint) were decreased. These changes in iron-handling proteins after light exposure are likely due to a disturbance in the iron storage pool evident from decreased ferritin levels, which would result in increased intracellular Fe²⁺ levels. To counteract this, Fe²⁺ is released into the extracellular space, an observation supported by increased expression of ferroportin-1. Ceruloplasmin was able to convert Fe²⁺ into Fe³⁺ until 48 h of light exposure, but its decreased expression with time (at 168-h timepoint) resulted in increased extracellular Fe²⁺ that might have caused oxidative stress and retinal cell damage.

TIMP-1 activated carcinoma-associated fibroblasts inhibit tumor apoptosis by activating SDF1/CXCR4 signaling in hepatocellular carcinoma

Tissue inhibitor of metalloproteinase 1 (TIMP-1) is an endogenous inhibitor for MMPs that regulates the remodeling and turnover of the ECM during normal development and pathological conditions. Intriguingly, recent studies have shown that TIMP-1 plays a dual role in cancer progression. In this study, we found that TIMP-1 expression in HCC tissues is associated with advanced TNM stage, intrahepatic metastasis, portal vein invasion, and vasculature invasion. Notably, TIMP-1 expression in HCC tissue is significantly related to worse overall survival for patients with HCC after liver resection. Ectopic TIMP1 expression promoted the growth of HCC xenografts in nude mice. Both co-culture with Huh7 cells with a high level of TIMP-1 and TIMP1 treatment resulted in up-regulation of hallmarks of carcinoma-associated fibroblasts (CAFs) and accelerated cell proliferation, migration and invasion in immortalized liver fibroblasts (LFs) isolated from human normal liver tissue. By co-culture with CAFs, SDF-1/CXCR4/PI3K/AKT signaling was activated and apoptosis was markedly repressed with an increased Bcl-2/BAX ratio in Huh7 cells. Taken together, our observations suggest that TIMP-1 induces the trans-differentiation of LFs into CAFs, suppresses apoptosis via SDF-1/CXCR4/PI3K/AKT signaling and then promotes HCC progression. This protein may be a potential prognostic biomarker and therapeutic target for HCC.