Bone growth into a ceramic-filled defect around an implant - The response to transforming growth factor beta 1

Synthetic bone substitutes provide an alternative to autograft but do not give equivalent clinical results. Their performance may be enhanced by adding osteogenic growth factors. In this study, TGFbeta1 was absorbed on to a carrier of 0 tricalcium phosphate and Gelfoam(R) and used to fill a defect around a tibial implant in a rat model of revision arthoplasty.

Oncogenic Kras Promotes Chemotherapy-Induced Growth Factor Shedding via ADAM17.

Oncogenic mutations in Kras occur in 40% to 45% of patients with advanced colorectal cancer (CRC). We have previously shown that chemotherapy acutely activates ADAM17, resulting in growth factor shedding, growth factor receptor activation, and drug resistance in CRC tumors. In this study, we examined the role of mutant Kras in regulating growth factor shedding and ADAM17 activity, using isogenic Kras mutant (MT) and wild-type (WT) HCT116 CRC cells. Significantly higher levels of TGF-a and VEGF were shed from KrasMT HCT116 cells, both basally and following chemotherapy treatment, and this correlated with increased pErk (phosphorylated extracellular signal regulated kinase)1/2 levels and ADAM17 activity. Inhibition of Kras, MEK (MAP/ERK kinase)1/2, or Erk1/2 inhibition abrogated chemotherapy-induced ADAM17 activity and TGF-a shedding. Moreover, we found that these effects were not drug or cell line specific. In addition, MEK1/2 inhibition in KrasMT xenografts resulted in significant decreases in ADAM17 activity and growth factor shedding in vivo, which correlated with dramatically attenuated tumor growth. Furthermore, we found that MEK1/2 inhibition significantly induced apoptosis both alone and when combined with chemotherapy in KrasMT cells. Importantly, we found that sensitivity to MEK1/2 inhibition was ADAM17 dependent in vitro and in vivo. Collectively, our findings indicate that oncogenic Kras regulates ADAM17 activity and thereby growth factor ligand shedding in a MEK1/2/Erk1/2-dependent manner and that KrasMT CRC tumors are vulnerable to MEK1/2 inhibitors, at least in part, due to their dependency on ADAM17 activity.

Retinal vascular endothelial cell endocytosis increases in early diabetes.

BACKGROUND: Several physiological studies in recent years have convincingly demonstrated increased clearance of intravascular protein tracers by several different tissues, including the retina, during early diabetes and galactosemia in the rat. This change has been described as a consequence of increased permeation, although vascular leakage has not been demonstrated, and the fate of such tracers remains unelucidated. EXPERIMENTAL DESIGN: A pilot study in this laboratory showed no evidence of vascular leakage but suggested increased endocytosis of horseradish peroxidase (HRP) by retinal vascular endothelial cells (RVECs) in early diabetes. We therefore quantified RVEC endocytosis in normal, streptozotocin (STZ)-treated nondiabetic and STZ-diabetic rats using the design-based stereology method of "vertical sections." A duration of diabetes (6 weeks) was chosen to approximate the time period in which other workers have demonstrated increased protein permeation of the retina. RESULTS: After a 20-minute exposure to the tracer, HRP reaction product was observed in small vesicular and tubular endosomes and larger multivesicular bodies of the RVECs. Stereological analysis revealed a 6.5-fold increase in the volume of HRP-containing organelles in the RVECs of diabetic rats compared with STZ-treated nondiabetics or normal controls. None of the animals in this study showed HRP reaction product outside the retinal vascular endothelium. CONCLUSIONS: A highly significant increase in RVEC endocytosis occurs in early diabetes. Increased RVEC endocytosis may contribute to the observed clearance of intravascular protein tracers by the retina during early diabetes.

Increased endocytosis in retinal vascular endothelial cells grown in high glucose medium is modulated by inhibitors of nonenzymatic glycosylation

We sought to determine if hyperglycaemia is responsible for increased retinal vascular endothelial-cell (RVEC) endocytosis in diabetes and to assess the role of nonenzymatic glycosylation in mediation of this novel endothelial-cell pathology. RVECs were propagated in media containing either 5 or 25 mmol/l glucose for up to 10 days after which they were exposed to the protein tracer horseradish peroxidase for 30 min. The level of RVEC endocytosis was quantified in intact cell monolayers by electron microscopic stereology, and in cell lysates by a simple spectrophotometric method. The effect of the nonenzymatic glycosylation inhibitors, aminoguanidine and D-lysine, on high-glucose medium induced changes in RVEC endocytosis was tested by inclusion of these agents in the culture medium. RVECs exposed to 25 mmol/l glucose showed a stepwise increase in endocytosis of horseradish peroxidase culminating in a two- to threefold increase after 10 days. Endocytosis returned to normal levels after a further 10 days in 5 mmol/l glucose medium. The increase in RVEC endocytosis was markedly reduced, but not completely normalised, by aminoguanidine and D-lysine. Exposure of cultured RVECs to 25 mmol/l glucose causes an increase in endocytosis of similar magnitude to that experienced by RVEC in early diabetes, and implicates hyperglycaemia in the latter situation. A significant component of the increase in RVEC endocytosis appears to be mediated by nonenzymatic glycosylation.

Effect of lycopene supplementation on insulin-like growth factor-1 and insulin-like growth factor binding protein-3: a double-blind, placebo-controlled trial

Objective: Studies have suggested a link between lycopene and insulin-like growth factor-1 ( IGF-1). The aim of this study was to test the effect of lycopene supplementation on IGF-1 and binding protein-3 ( IGFBP-3) status in healthy male volunteers.

Short-term phytoestrogen supplementation alters insulin-like growth factor profile but not lipid or antioxidant status

Phytoestrogens are plant compounds that have been proposed to have a variety of health benefits. The aim of this study was to assess the effects of these compounds on a number of physiological endpoints. Subjects were given a single intake of a phytoestrogen-rich (80 mg total phytoestrogens) supplement containing soy, rye and linseed (Phase 1), followed by a week-long intervention using the same supplement (Phase 2) (80 mg total phytoestrogens daily). A number of biochemical endpoints were assessed including urinary phytoestrogen metabolites, lipids, antioxidant status, DNA damage and insulin-like growth factor-1 (IGF-1) and IGF binding protein-1 (IGFBP-1) and -3 (IGFBP-3). Ten healthy female subjects took part in the study. Excretion of the isoflavones genistein, daidzein and equol in urine increased in both phases of the study. No other endpoint was altered in Phase 1. However, in Phase 2, concentrations of IGF-1 and IGFBP-3 were increased by phytoestrogen supplementation [IGF-1, median (IQ range), baseline 155 (123, 258), postweek 265 (228, 360) ng/ml, P

Effect of red clover-derived isoflavone supplementation on insulin-like growth factor, lipid and antioxidant status in healthy female volunteers: a pilot study

Background: Isoflavones are estrogen-like plant compounds that may protect against cardiovascular disease and endocrine-responsive cancer. Isoflavones may, because of their ability to act as selective estrogen receptor modulators, alter insulin-like growth factor (IGF) status.

Progressive loss of epidermal growth factor receptor in a subpopulation of breast cancers: implications in target-directed therapeutics

Understanding the molecular etiology and heterogeneity of disease has a direct effect on cancer therapeutics. To identify novel molecular changes associated with breast cancer progression, we conducted phosphoproteomics of the MCF10AT model comprising isogenic, ErbB2- and ErbB3-positive, xenograft-derived cell lines that mimic different stages of breast cancer. Using in vitro animal model and clinical breast samples, our study revealed a marked reduction of epidermal growth factor receptor (EGFR) expression with breast cancer progression. Such diminution of EGFR expression was associated with increased resistance to Gefitinib/Iressa in vitro. Fluorescence in situ hybridization showed that loss of EGFR gene copy number was one of the key mechanisms behind the low/null expression of EGFR in clinical breast tumors. Statistical analysis on the immunohistochemistry data of EGFR expression from 93 matched normal and breast tumor samples showed that (a) diminished EGFR expression could. be detected as early as in the preneoplastic lesion (ductal carcinoma in situ) and this culminated in invasive carcinomas; (b) EGFR expression levels could distinguish between normal tissue versus carcinoma in situ and invasive carcinoma with high statistical significance (P

Detection of epidermal growth factor receptor variations by partially denaturing HPLC

Background: Epidermal growth factor receptor gene (EGFR) variants may be useful markers for identifying responders to gefitinib and erlotinib, small-molecule tyrosine kinase inhibitors of EGFR; therefore, sensitive and cost-effective assays are needed to detect EGFR variants in routine clinical samples. We have developed a partially denaturing HPLC (pDHPLC) assay that is superior to direct sequencing with respect to detection limits, costs, and time requirements.