Fibronectin-binding protein TDE1579 affects cytotoxicity of Treponema denticola.

While FbpA, a family of bacterial fibronectin (FN) binding proteins has been studied in several gram-positive bacteria, the gram-negative Treponema denticola, an anaerobic periodontal pathogen, also has an overlooked fbp gene (tde1579). In this research, we confirm that recombinant Fbp protein (rFbp) of T. denticola binds human FN with a Kdapp of 1.

Identification of collagen binding domain residues that govern catalytic activities of matrix metalloproteinase-2 (MMP-2).

An innovative approach to enhance the selectivity of matrix metalloproteinase (MMP) inhibitors comprises targeting these inhibitors to catalytically required substrate binding sites (exosites) that are located outside the catalytic cleft. In MMP-2, positioning of collagen substrate molecules occurs via a unique fibronectin-like domain (CBD) that contains three distinct modular collagen binding sites. To characterize the contributions of these exosites to gelatinolysis by MMP-2, seven MMP-2 variants were generated with single, or concurrent double and triple alanine substitutions in the three fibronectin type II modules of the CBD.

Dual EGFR/HER2 inhibition sensitizes prostate cancer cells to androgen withdrawal by suppressing ErbB3.

Purpose: Patients with recurrent prostate cancer are commonly treated with androgen withdrawal therapy (AWT); however, almost all patients eventually progress to castration resistant prostate cancer (CRPC), indicating failure of AWT to eliminate androgen-sensitive prostate cancer. The overall goal of these studies is to determine whether dual inhibition of the receptor tyrosine kinases epidermal growth factor receptor (EGFR) and HER2 would prolong the effectiveness of this treatment in prostate cancer.

Experimental Design: We used androgen-dependent LNCaP cells and its CRPC sublines LNCaP-AI and C4-2.

Peptide from the C-terminal domain of tissue inhibitor of matrix metalloproteinases-2 (TIMP-2) inhibits membrane activation of matrix metalloproteinase-2 (MMP-2).

Cellular activation of latent matrix metalloproteinase-2 (proMMP-2) requires formation of a cell membrane-associated activation complex that involves specific binding between the hemopexin domain of proMMP-2 (PEX) and the C-terminal domain of tissue inhibitor of matrix metalloproteinases-2 (C-TIMP-2). In this study, we tested the feasibility of inhibiting activation of proMMP-2 by exogenous inhibitors, which block the binding between PEX and TIMP-2. The recombinant C-TIMP-2 and synthetic peptides from C-TIMP-2 were used as inhibitors for proMMP-2 activation.

Fragmentation of fibronectin by inherent autolytic and matrix metalloproteinase activities.

Fibronectin (FN) purified by gelatin affinity chromatography is unstable and undergoes fragmentation. The cleavage has been ascribed to inherent autolytic protease activities as well as co-purified matrix metalloproteinases (MMP). Understanding the mechanism by which the proteolysis of FN occurs is important, because the FN fragments have biological activities that differ from those of intact FN.

Nuclear magnetic resonance mapping and functional confirmation of the collagen binding sites of matrix metalloproteinase-2.

Interactions of matrix metalloproteinase-2 (MMP-2) with native and denatured forms of several types of collagen are mediated by the collagen binding domain (CBD). CBD positions substrates relative to the catalytic site and is essential for their cleavage. Our previous studies identified a CBD binding site on the alpha1(I) collagen chain.

Advanced glycation of type I collagen and fibronectin modifies periodontal cell behavior.

Background: Advanced glycation end products (AGEs) have been linked to pathogenic mechanisms of diabetes mellitus. However, little is known about the contribution of protein glycation to periodontal disease in patients with diabetes. Therefore, this study investigated whether glycation of type I collagen (COLI) and fibronectin (FN) modified the behavior of human gingival fibroblasts (hGFs) and periodontal ligament fibroblasts (hPDLs).

AKT regulates androgen receptor-dependent growth and PSA expression in prostate cancer.

Recurrent prostate cancer (PC) is usually treated with androgen deprivation therapy, which, despite initial success, eventually fails due to the development of androgen-independent PC. Androgen deprivation stimulates a significant increase in the phosphorylation (activation) of Akt, a serine/threonine kinase, which regulates cell growth and survival. Hence, we asked whether the increase in Akt phosphorylation contributes to the development of androgen independence.

Flavonoid, silibinin, inhibits proliferation and promotes cell-cycle arrest of human colon cancer.

Background: Anti-oxidative extracts from the milk thistle plant (Silybum marianum) have been shown to have antiproliferative effects in several tumor types. Silibinin is the primary active component isolated from the crude seed extract, silymarin. It has been used as a dietary supplement for hepatoprotection for over 2000 years.

Regulation of caspase-9 activity by differential binding to the apoptosome complex.

Proteolytic processing of procaspase-9 is required for its activation, but processing in itself appears to be insufficient for its activity. We studied caspase activation in a cell-free system and found that incubation of cytosol from rat kidney proximal tubule cells with Cytochrome c (Cyt c) and dATP results in rapid autocatalytic processing of procaspase-9 from ~50 kD to ~38 kD size fragment. Moreover, Cyt c concentration influences the production of alternatively processed forms of caspase-9.

Signal transduction pathways in androgen-dependent and -independent prostate cancer cell proliferation.

In a previous report, we showed that increased activation of Akt, a downstream effector of phosphoinositide 3-kinase (PI3K) together with decreased activation of extracellular-signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase (MAPK) family, predicted poor clinical outcome in prostate cancer (Kreisberg et al. 2004 Cancer Research 64 5232-5236). We now show that Akt activation, but not ERK activation, is correlated with proliferation in human prostate tumors as estimated by the expression of the cell proliferation antigen Ki67.

Association of Bax and Bak homo-oligomers in mitochondria. Bax requirement for Bak reorganization and cytochrome c release.

ATP depletion induced by hypoxia or mitochondrial inhibitors results in Bax translocation from cytosol to mitochondria and release of cytochrome c from mitochondria into cytosol in cultured rat proximal tubule cells. Translocated Bax undergoes further conformational changes to oligomerize into high molecular weight complexes (Mikhailov, V., Mikhailova, M.