EGF and IL-1 alpha modulate the release of collagenase, gelatinase and TIMP-1 as well as the release of calcium by rabbit calvarial bone explants

Carnosol, a Natural Polyphenol, Inhibits Migration, Metastasis, and Tumor Growth of Breast Cancer via a ROS-Dependent Proteasome Degradation of STAT3

We have previously demonstrated that carnosol, a naturally occurring diterpene, inhibited in vitro cell viability and colony growth, as well as induced cell cycle arrest, autophagy and apoptosis in human triple negative breast cancer (TNBC) cells. In the present study, we evaluated the ability of carnosol to inhibit tumor growth and metastasis in vivo. We found that non-cytotoxic concentrations of carnosol inhibited the migration and invasion of MDA-MB-231 cells in wound healing and matrigel invasion assays. Furthermore, gelatin zymography, ELISA, and RT-PCR assays revealed that carnosol inhibited the activity and downregulation the expression of MMP-9. Mechanistically, we demonstrated that carnosol suppressed the activation of STAT3 signaling pathway through a ROS-dependent targeting of STAT3 to proteasome-degradation in breast cancer cells (MDA-MB-231, Hs578T, MCF-7, and T47D). We show that blockade of proteasome activity, by MG-132 and bortezomib, or ROS accumulation, by N-acetylcysteine (NAC), restored the level of STAT3 protein. In addition, using chick embryo tumor growth assay, we showed that carnosol significantly and markedly suppressed tumor growth and metastasis of breast cancer xenografts. To the best of our knowledge, this is the first report which shows that carnosol specifically targets signal transducer and activator of transcription 3 (STAT3) for proteasome degradation in breast cancer. Our study further provide evidence that carnosol may represent a promising therapeutic candidate that canmodulate breast cancer growth and metastasis.

Migfilin protein promotes migration and invasion in human glioma through epidermal growth factor receptor-mediated phospholipase C-γ and STAT3 protein signaling pathways

Migfilin is critical for cell shape and motile regulation. However, its pathological role in glioma is unknown. Using an immunohistochemical staining assay, we demonstrate that there is a significant correlation between expression of Migfilin and pathological tumor grade in 217 clinical glioma samples. High Migfilin expression is associated with poor prognosis for patients with glioma. Investigation of the molecular mechanism shows that Migfilin promotes migration and invasion in glioma cells. Moreover, Migfilin positively modulates the expression and activity of epidermal growth factor receptor, and Migfilin-mediated migration and invasion depend on epidermal growth factor receptor-induced PLC-γ and STAT3-signaling pathways. Our results may provide significant clinical application, including use of Migfilin as a molecular marker in glioma for early diagnosis and as an indicator of prognosis.

Matrix metalloproteinases 2 and 9 are dispensable for pancreatic islet formation and function in vivo

Pancreatic islet formation is a highly regulated process that is initiated at the end of gestation in rodents. Endocrine precursor cells first form within the epithelium of duct-like structures and then delaminate from the epithelium, migrate, and cluster during the early stages of islet formation. The molecular mechanisms that regulate endocrine cell migration and islet formation are not well understood. Cell culture studies suggest that matrix metalloproteinases (MMPs) 2 and 9 are required for islet formation. To address whether MMP2 and MMP9 function are essential for endocrine cell migration and islet formation in vivo, we analyzed pancreas development in MMP2/MMP9 double-deficient mice. Our results show that islet architecture and function are unperturbed in these knockout mice, demonstrating that both MMP2 and MMP9 functions are dispensable for islet formation and endocrine cell differentiation. Our studies also show that a number of other MMPs are expressed at the time islet formation is initiated. This observation suggests that other MMPs may substitute for MMP2 and MMP9 loss in pancreatic tissue. However, islet formation is unaffected in transgenic mice with modified tissue inhibitor of metalloproteinase-1 (TIMP1) levels, suggesting that MMP activity may contribute little to islet morphogenesis in vivo.

IP-10 inhibits epidermal growth factor-induced motility by decreasing epidermal growth factor receptor-mediated calpain activity

During wound healing, fibroblasts are recruited from the surrounding tissue to accomplish repair. The requisite migration and proliferation of the fibroblasts is promoted by growth factors including those that activate the epidermal growth factor receptor (EGFR). Counterstimulatory factors in wound fluid are postulated to limit this response; among these factors is the ELR-negative CXC chemokine, interferon inducible protein-10 (IP-10). We report here that IP-10 inhibited EGF- and heparin-binding EGF-like growth factor-induced Hs68 human dermal fibroblast motility in a dose-dependent manner (to 52% and 44%, respectively, at 50 ng/ml IP-10), whereas IP-10 had no effect on either basal or EGFR-mediated mitogenesis (96 +/- 15% at 50 ng/ml). These data demonstrate for the first time a counterstimulatory effect of IP-10 on a specific induced fibroblast response, EGFR-mediated motility. To define the molecular basis of this negative transmodulation of EGFR signaling, we found that IP-10 did not adversely impact receptor or immediate postreceptor signaling as determined by tyrosyl phosphorylation of EGFR and two major downstream effectors phospholipase C-gamma and erk mitogen-activated protein kinases. Morphological studies suggested which biophysical steps may be affected by demonstrating that IP-10 treatment resulted in an elongated cell morphology reminiscent of failure to detach the uropod; in support of this, IP-10 pretreatment inhibited EGF-induced cell detachment. These data suggested that calpain activity may be involved. The cell permeant agent, calpain inhibitor I, limited EGF-induced motility and de-adhesion similarly to IP-10. IP-10 also prevented EGF- induced calpain activation (reduced by 71 +/- 7%). That this inhibition of EGF-induced calpain activity was secondary to IP-10 initiating a cAMP-protein kinase A-calpain cascade is supported by the following evidence: (a) the cell permeant analogue 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) prevented EGF-induced calpain activity and motility; (b) other ELR-negative CXC chemokines, monokine induced by IFN-gamma and platelet factor 4 that also generate cAMP, inhibited EGF-induced cell migration and calpain activation; and (c) the protein kinase A inhibitor Rp-8-Br-cAMPS abrogated IP-10 inhibition of cell migration, cell detachment, and calpain activation. Our findings provide a model by which IP-10 suppresses EGF-induced cell motility by inhibiting EGF-induced detachment of the trailing edges of motile cells.