A chimeric antibody targeting CD147 inhibits hepatocellular carcinoma cell motility via FAK-PI3K-Akt-Girdin signaling pathway.

CD147 is expressed at low levels in normal tissues but frequently highly expressed in a wide range of tumor types such as lung, breast, and liver and therefore it is a potentially unique therapeutic target for these diverse tumor types. We previously generated a murine antibody HAb18 which suppresses matrix met al.loproteinase-2 and matrix metalloproteinase-9 secretion, attenuates cell invasion by blocking the CD147 molecule in tumor cells. Here, we generated a chimeric antibody containing the variable heavy and variable light chains of murine HAb18 and the constant regions of human IgG1γ1 and human κ chain as a potential therapeutic agent (designated cHAb18). Quantitative measurement of cHAb18 antibody affinity for antigen CD147 with surface plasmon resonance showed the equilibrium dissociation constant KD was 2.66 × 10(-10) mol/L, similar to that of KD 2.73 × 10(-10) mol/L for murine HAb18. cHAb18 induced antibody-dependent cell-mediated cytotoxicity in two hepatocellular carcinoma cell lines, SMMC-7721 and Huh-7 cells. It inhibited cancer invasion and migration in hepatocellular carcinoma cells by specifically blocking CD147. Except for the depression of matrix metalloproteinase-2 and matrix metalloproteinase-9 expressions, cHAb18 antibody suppressed cell motility by rearrangement of actin cytoskeleton, which was probably induced by decreasing the phosphorylation of focal adhesion kinase, phosphatidylinositide-3 kinase (PI3K), Akt, and Girdin in the integrin signaling pathway. In an orthotopic model of hepatocellular carcinoma in BALB/c nude mice, cHAb18 treatment effectively reduced the tumor metastasis in liver and prolonged the survival. These findings reveal new therapeutic potential for cHAb18 antibody targeting CD147 on tumor therapy.

Human B cells express the orphan chemokine receptor CRAM-A/B in a maturation-stage-dependent and CCL5-modulated manner.

Chemokines orchestrate the organization of leucocyte recruitment during inflammation and homeostasis. Despite growing knowledge of chemokine receptors, some orphan chemokine receptors are still not characterized. The gene CCRL2 encodes such a receptor that exists in two splice variants, CRAM-A and CRAM-B. Here, we report that CRAM is expressed by human peripheral blood and bone marrow B cells, and by different B-cell lines dependent on the B-cell maturation stage. Intriguingly, CRAM surface expression on the pre-B-cell lines Nalm6 and G2 is specifically upregulated in response to the inflammatory chemokine CCL5 (RANTES), a chemokine that is well known to play an important role in modulating immune responses. Although Nalm6 cells do not express any of the known CCL5 binding receptors, extracellular signal-regulated kinases 1 and 2 (ERK1/2) are phosphorylated upon CCL5 stimulation, suggesting a direct effect of CCL5 through the CRAM receptor. However, no calcium mobilization or migratory responses upon CCL5 stimulation are induced in B-cell lines or in transfected cells. Also, ERK1/2 phosphorylation cannot be inhibited by pertussis toxin, suggesting that CRAM does not couple to Gi proteins. Our results describe the expression of a novel, non-classical chemokine receptor on B cells that is potentially involved in immunomodulatory functions together with CCL5.

Direct ANP inhibition of hypoxia-induced inflammatory pathways in pulmonary microvascular and macrovascular endothelial monolayers.

Atrial natriuretic peptide (ANP) has been shown to reduce hypoxia-induced pulmonary vascular leak in vivo, but no explanation of a mechanism has been offered other than its vasodilatory and natriuretic actions. Recently, data have shown that ANP can protect endothelial barrier functions in TNF-alpha-stimulated human umbilical vein endothelial cells. Therefore, we hypothesized that ANP actions would inhibit pulmonary vascular leak by inhibition of TNF-alpha secretion and F-actin formation. Bovine pulmonary microvascular (MVEC) and macrovascular endothelial cell (LEC) monolayers were stimulated with hypoxia, TNF-alpha, or bacterial endotoxin (LPS) in the presence or absence of ANP, and albumin flux, NF-kappa B activation, TNF-alpha secretion, p38 mitogen-activated protein kinase (MAPK), and F-actin (stress fiber) formation were assessed. In Transwell cultures, ANP reduced hypoxia-induced permeability in MVEC and TNF-alpha-induced permeability in MVEC and LEC. ANP inhibited hypoxia and LPS increased NF-kappa B activation and TNF-alpha synthesis in MVEC and LEC. Hypoxia decreased activation of p38 MAPK in MVEC but increased activation of p38 MAPK and stress fiber formation in LEC; TNF-alpha had the opposite effect. ANP inhibited an activation of p38 MAPK in MVEC or LEC. These data indicate that in endothelial cell monolayers, hypoxia activates a signal cascade analogous to that initiated by inflammatory agents, and ANP has a direct cytoprotective effect on the pulmonary endothelium other than its vasodilatory and natriuretic properties. Furthermore, our data show that MVEC and LEC respond differently to hypoxia, TNF-alpha-stimulation, and ANP treatment.