Itzhak D. Goldberg

Regulation of angiogenesis

Angiogenesis and angiogenesis inhibition: An overview.- Significance of angiogenesis in human disease.- Role of the macrophage in angiogenesis-dependent diseases.- Angiogenesis in human gliomas: Prognostic and therapeutic implications.- Regulation of angiogenesis in malignant gliomas.- Lymphangiogenesis: Mechanisms, significance and clinical implications.- Angiogenesis as a biologic and prognostic indicator in human breast carcinoma.- Molecular mechanisms of angiogenesis regulation.- Control of angiogenesis by cytokines and growth factors.- Fibroblast growth factors as angiogenesis factors: New insights into their mechanism of action.- Regulation of angiogenesis by scatter factor.- Vascular endothelial growth factor: Basic biology and clinical implications.- Vascular permeability factor/vascular endothelial growth factor: A multifunctional angiogenic cytokine.- Angiogenesis inhibition.- Angiostatin: An endogenous inhibitor of angiogenesis and of tumor growth.- Thrombospondin as a regulator of angiogenesis.- Regulation of angiogenesis by cell-matrix cell-cell and other interactions.- Regulation of capillary formation by laminin and other components of the extracellular matrix.- Hypoxia and angiogenesis in experimental tumor models: Therapeutic implications.- The role of vascular cell integrins ?v?3 and ?v?5 in angiogenesis.- Role of fibrin and plasminogen activators in repair-associated angiogenesis: In vitro studies with human endothelial cells.- Tumor angiogenesis: Functional similarities with tumor invasion.- Control of angiogenesis by the pericyte: Molecular mechanisms and significance.

The cytokine hepatocyte growth factor/scatter factor inhibits apoptosis and enhances DNA repair by a common mechanism involving signaling through phosphatidyl inositol 3' kinase.

Scatter factor (SF) [aka. hepatocyte growth factor (HGF)] (designated HGF/SF) is a multifunctional cytokine that stimulates tumor cell invasion and angiogenesis. We recently reported that HGF/SF protects epithelial and carcinoma cells against cytotoxicity from DNA-damaging agents and that HGF/SF-mediated cytoprotection was associated with up-regulation of the anti-apoptotic protein Bcl-XL in cells exposed to adriamycin. We now report that in addition to blocking apoptosis, HGF/SF markedly enhances the repair of DNA strand breaks caused by adriamycin or gamma radiation. Constitutive expression of Bcl-XL in MDA-MB-453 breast cancer cells not only simulated the HGF/SF-mediated chemoradioresistance, but also enhanced the repair of DNA strand breaks. The ability of HGF/SF to induce both chemoresistance and DNA repair was inhibited by wortmannin, suggesting that these activities of HGF/SF are due, in part, to a phosphatidylinositol-3′-kinase (PI3K) dependent signaling pathway. Consistent with this finding, HGF/SF induced the phosphorylation of c-Akt (protein kinase-B), a PI3K substrate implicated in apoptosis inhibition; and an expression vector encoding a dominant negative kinase inactive Akt partially but significantly inhibited HGF/SF-mediated cell protection and DNA repair. These findings suggest that HGF/SF activates a cell survival and DNA repair pathway that involves signaling through PI3K and c-Akt and stabilization of the expression of Bcl-XL; and they implicate Bcl-XL in the DNA repair process.

Scatter factor promotes motility of human glioma and neuromicrovascular endothelial cells

Malignant gliomas are characterized by rapid growth, infiltration of normal brain tissue, and high levels of tumor‐associated angiogenesis. The genetic and local environmental tissue factors responsible for the malignant progression from low to high grade gliomas and the highly malignant behavior of glioblastomas are not well understood. In a study of 77 human brain tissue extracts, high grade (III‐IV) tumors had significantly greater scatter factor (SF) content than did low grade tumors or non‐neoplastic tissue. To investigate the potential significance of SF accumulation in gliomas, we measured the effects of SF on DNA synthesis and motility of cultured human glioma cell lines. SF stimulated DNA synthesis in 7/10 glioma cell lines and in 3/3 neuromicrovascular endothelial cell (NMVEC) lines, consistent with our previous report that SF stimulated cell proliferation of a few human glioma cell lines. SF markedly stimulated the chemotactic migration of 10/10 glioma cell lines as well as 3/3 NMVEC lines. In addition, SF stimulated the 2‐dimensional migration of glioma cells on culture surfaces coated with specific extracellular matrix molecules (collagen IV, laminin, and fibronection). As expected based on these biologic responses to SF, 10/10 glioma lines and 4/4 NMVEC lines expressed mRNA for c‐met, the SF receptor. To assess the possible in vivo significance of these migration assays, we compared the chemotactic response of a glioma cell line to human brain cyst fluids and tumor extracts that contained high or low SF concentrations. Fluids and extracts with high SF content tended to induce higher levels of chemotactic migration than did fluids and extracts with low SF content. Addition of anti‐SF monoclonal antibody (MAb) inhibited migration induced by fluids and extracts with high SF content by about 30–50%. Int. J. Cancer 75:19–28, 1998.© 1998 Wiley‐Liss, Inc.

Scatter factor expression and regulation in human glial tumors

Scatter factor (SF) (also known as hepatocyte growth factor [HGF]) is a cytokine that induces cell motility in vitro and angiogenesis in vivo. SF appears to be a determinant of the malignant phenotype in certain systemic cancers. We detected SF in extracts prepared from human gliomas, with the highest levels found in malignant tumors. Human glioblastoma cells expressed both SF and its receptor (c‐met protein) in vivo, as demonstrated by immunohistochemistry. Consistent with these observations, we found moderate to high levels of production of immunoreactive and biologically active SF by cultured human glioblastoma cells (3 of 8 lines) and by neural microvascular endothelial cells (NMVEC) (3 of 3 lines). SF stimulated the proliferation of glioblastoma and NMVEC cell lines by paracrine or autocrine mechanisms. Conditioned medium (CM) from both glioblastoma and NMVEC cells contained SF‐inducing factor (SF‐IF) activity, defined by its ability to stimulate SF production in an indicator cell line (MRC5 human fibroblasts). This activity consisted of a high‐molecular‐weight (>30 kDa), heat‐sensitive component and a low‐molecular weight (<30 kDa), heat‐stable component. Furthermore, glioblastoma CM stimulated NMVEC SF production, and NMVEC CM stimulated glioblastoma cell SF production, by 3‐ to 6‐fold in each case. Our findings demonstrate that SF‐dependent interactions between glioma cells, and between glioma cells and endothelium, can contribute to the heterogeneous proliferative and angiogenic phenotypes of malignant gliomas in vivo.

Role of NF-κB signaling in hepatocyte growth factor/scatter factor-mediated cell protection

The cytokine scatter factor/hepatocyte growth factor (HGF/SF) protects epithelial, carcinoma, and other cell types against cytotoxicity and apoptosis induced by DNA-damaging agents such as ionizing radiation and adriamycin (ADR, a topoisomerase IIα inhibitor). We investigated the role of nuclear factor kappa B (NF-κB) signaling in HGF/SF-mediated protection of human prostate cancer (DU-145) and Madin–Darby canine kidney (MDCK) epithelial cells against ADR. HGF/SF caused the rapid nuclear translocation of the p65 (RelA) subunit of NF-κB associated with the transient loss of the inhibitory subunit IκB-α. Exposure to HGF/SF caused the activation of an NF-κB luciferase reporter that was blocked or attenuated by the expression of a mutant ‘super-repressor’ IκB-α. Electrophoretic mobility shift assay supershift assays revealed that HGF/SF treatment induced the transient binding of various NF-κB family proteins (p65, p50, c-Rel, and RelB) with radiolabeled NF-κB-binding oligonucleotides. The HGF/SF-mediated protection of DU-145 and MDCK cells against ADR (demonstrated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays) was abrogated by the IκB-α super-repressor. The ability of HGF/SF to activate NF-κB signaling was dependent on c-Akt → Pak1 (p21-associated kinase-1) signaling (with Pak1 downstream of c-Akt) and was inhibited by the tumor suppressor PTEN (phosphatase and tensin homolog). Inhibitors of phosphatidylinositol-3′-kinase and Src family kinases significantly inhibited HGF/SF-mediated activation of NF-κB, while inhibitors of MEK, protein kinase C, and p70 S6 kinase had a modest effect or no effect on NF-κB activity. HGF/SF induced the expression of several known NF-κB target genes (cIAP-1 (cellular inhibitor of apoptosis-1), cIAP-2, and TRAF-2 (TNF receptor-associated factor-2)) in an NF-κB-dependent manner; HGF/SF blocked the inhibition of expression of these genes by ADR. Experimental manipulation of expression of these genes suggests that they (particularly TRAF-2 and cIAP-2) contribute to the protection against ADR by HGF/SF. These findings suggest that HGF/SF activates NF-κB through a c-Akt → Pak1 signaling pathway that is also dependent on Src, and that NF-κB contributes to HGF/SF-mediated protection against ADR.

Perlecan Mediates the Antiproliferative Effect of Apolipoprotein E on Smooth Muscle Cells AN UNDERLYING MECHANISM FOR THE MODULATION OF SMOOTH MUSCLE CELL GROWTH

Apolipoprotein E (apoE) is known to inhibit cell proliferation; however, the mechanism of this inhibition is not clear. We recently showed that apoE stimulates endothelial production of heparan sulfate (HS) enriched in heparin-like sequences. Because heparin and HS are potent inhibitors of smooth muscle cell (SMC) proliferation, in this study we determined apoE effects on SMC HS production and cell growth. In confluent SMCs, apoE (10 μg/ml) increased 35SO4 incorporation into PG in media by 25–30%. The increase in the medium was exclusively due to an increase in HSPGs (2.2-fold), and apoE did not alter chondroitin and dermatan sulfate proteoglycans. In proliferating SMCs, apoE inhibited [3H]thymidine incorporation into DNA by 50%; however, despite decreasing cell number, apoE increased the ratio of35SO4 to [3H]thymidine from 2 to 3.6, suggesting increased HS per cell. Purified HSPGs from apoE-stimulated cells inhibited cell proliferation in the absence of apoE. ApoE did not inhibit proliferation of endothelial cells, which are resistant to heparin inhibition. Analysis of the conditioned medium from apoE-stimulated cells revealed that the HSPG increase was in perlecan and that apoE also stimulated perlecan mRNA expression by >2-fold. The ability of apoE isoforms to inhibit cell proliferation correlated with their ability to stimulate perlecan expression. An anti-perlecan antibody completely abrogated the antiproliferative effect of apoE. Thus, these data show that perlecan is a potent inhibitor of SMC proliferation and is required to mediate the antiproliferative effect of apoE. Because other growth modulators also regulate perlecan expression, this may be a key pathway in the regulation of SMC growth.

Late intervention with the small molecule BB3 mitigates postischemic kidney injury

Ischemia-reperfusion-mediated acute kidney injury can necessitate renal replacement therapy and is a major cause of morbidity and mortality. We have identified BB3, a small molecule, which when first administered at 24 h after renal ischemia in rats, improved survival, augmented urine output, and reduced the increase in serum creatinine and blood urea nitrogen. Compared with control kidneys, the kidneys of BB3-treated animals exhibited reduced levels of kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, and reduced tubular apoptosis and acute tubular necrosis but enhanced tubular regeneration. Consistent with its hepatocyte growth factor-like mode of action, BB3 treatment promoted phosphorylation of renal cMet and Akt and upregulated renal expression of the survival protein Bcl-2. These data suggest that the kidney is amenable to pharmacotherapy even 24 h after ischemia-reperfusion and that activation of the hepatocyte growth factor signaling pathway with the small molecule BB3 confers interventional benefits late into ischemia-reperfusion injury. These data formed, in part, the basis for the use of BB3 in a clinical trial in kidney recipients presenting with delayed graft function.

An Empirical Biomarker-Based Calculator for Cystic Index in a Model of Autosomal Recessive Polycystic Kidney Disease—The Nieto-Narayan Formula

Autosomal recessive polycystic kidney disease (ARPKD) is associated with progressive enlargement of the kidneys fuelled by the formation and expansion of fluid-filled cysts. The disease is congenital and children that do not succumb to it during the neonatal period will, by age 10 years, more often than not, require nephrectomy+renal replacement therapy for management of both pain and renal insufficiency. Since increasing cystic index (CI; percent of kidney occupied by cysts) drives both renal expansion and organ dysfunction, management of these patients, including decisions such as elective nephrectomy and prioritization on the transplant waitlist, could clearly benefit from serial determination of CI. So also, clinical trials in ARPKD evaluating the efficacy of novel drug candidates could benefit from serial determination of CI. Although ultrasound is currently the imaging modality of choice for diagnosis of ARPKD, its utilization for assessing disease progression is highly limited. Magnetic resonance imaging or computed tomography, although more reliable for determination of CI, are expensive, time-consuming and somewhat impractical in the pediatric population. Using a well-established mammalian model of ARPKD, we undertook a big data-like analysis of minimally- or non-invasive blood and urine biomarkers of renal injury/dysfunction to derive a family of equations for estimating CI. We then applied a signal averaging protocol to distill these equations to a single empirical formula for calculation of CI. Such a formula will eventually find use in identifying and monitoring patients at high risk for progressing to end-stage renal disease and aid in the conduct of clinical trials.

Radiobiology of Blood Vessels

Why should the cancer specialist be interested in the radiobiology of blood vessels? This chapter will attempt to answer this question, review the current state of knowledge of vascular radiation biology and suggest directions for future investigations. Radiation effects on normal tissues are divided into two categories based on time of appearance. Acute effects occur during a course of fractionated radiation therapy or shortly thereafter. Late effects occur more than two months after completion of radiation and may appear many years later. Acute radiation damage to normal tissues can be understood in terms of cell proliferation kinetics (1). It results from an imbalance between cell killing and tissue regeneration. The latter may occur by recruitment of quiescent “stem” cells into the cell cycle; shortening of the cycle time of proliferating cells; or repopulation of the tissue with cells from outside of the irradiated field. The timing and severity of the acute effects depend upon : (1) transit time for maturing cells within the tissue compartment; (2) dose fraction size; and (3) protraction (the total time in which the radiation is delivered).

An Empirical Biomarker-based Calculator for Autosomal Recessive Polycystic Kidney Disease The Nieto-Narayan Formula

Autosomal polycystic kidney disease (ARPKD) is associated with progressive enlargement of the kidneys fuelled by the formation and expansion of fluid-filled cysts. The disease is congenital and children that do not succumb to it during the neonatal period will, by age 10 years, more often than not, require nephrectomy+renal replacement therapy for management of both pain and renal insufficiency. Since increasing cystic index (CI; percent of kidney occupied by cysts) drives both renal expansion and organ dysfunction, management of these patients, including decisions such as elective nephrectomy and prioritization on the transplant waitlist, could clearly benefit from serial determination of CI. So also, clinical trials in ARPKD evaluating the efficacy of novel drug candidates could benefit from serial determination of CI. Although ultrasound is currently the imaging modality of choice for diagnosis of ARPKD, its utilization for assessing disease progression is highly limited. Magnetic resonance imaging or computed tomography, although more reliable for determination of CI, are expensive, time-consuming and somewhat impractical in the pediatric population. Using a well-established mammalian model of ARPKD, we undertook a big data-like analysis of minimally- or non-invasive serum and urine biomarkers of renal injury/dysfunction to derive a family of equations for estimating CI. We then applied a signal averaging protocol to distill these equations to a single empirical formula for calculation of CI. Such a formula will eventually find use in identifying and monitoring patients at high risk for progressing to end-stage renal disease and aid in the conduct of clinical trials.