Increase in tissue inhibitor of metalloproteinase-2 (TIMP-2) levels and inhibition of MMP-2 activity in a metastatic breast cancer cell line by an anti-invasive small molecule SR13179.

Tissue inhibitor of metalloproteinase-2 (TIMP-2), the endogenous inhibitor of matrix metalloproteinase-2 (MMP-2), regulates tumor invasion by modulating the activity of MMP-2. In addition, TIMP-2 is involved in the direct regulation of cell growth and angiogenesis, independent of MMP inhibition. Therefore, the development of therapeutic agents that increase TIMP-2 levels may offer a novel and broad approach to anti-neoplastic therapy. We report that a novel small molecule synthetic flavanoid SR13179, which inhibits the invasion of a highly metastatic human breast cancer cell line MCF-10CA1a through Matrigel, significantly increases protein and mRNA levels of TIMP-2 in a time- and dose-dependent manner. SR13179 inhibits the gelatinolytic activity of MMP-2 by >50% but has no effect on MMP-2 protein expression. SR13179 also possesses potent anti-tumor activity in several tumor cell lines regardless of their hormone receptor, p53 or multi-drug resistance status. Given the multifunctional inhibitory activity of TIMP-2 on tumor growth and invasion, the observed increase in TIMP-2 expression by SR13179 may play a central role in the anti-tumor and anti-invasive activity of this novel small molecule. Modulation of TIMP-2 protein expression may be a new molecular target for anti-metastatic adjuvant therapy for breast and other cancers.

Improved lung growth and function through hypoxia-inducible factor in primate chronic lung disease of prematurity.

Bronchopulmonary dysplasia (BPD), a chronic lung disease affecting preterm neonates, is associated with significant childhood and adult health problems. Histopathologic features of BPD include impaired vascular and distal airway development. We previously showed that activation of hypoxia-inducible factors (HIFs) by inhibition of prolyl hydroxylase domain-containing proteins (PHDs) is feasible and that it stimulates vascular endothelial growth factor (VEGF)-dependent angiogenesis in vitro. We tested the hypothesis that enhancement of angiogenesis by activation of HIFs improves lung growth and function in prematurely born neonates in vivo. Preterm baboons (125 day+14 day pro re nata O2 model, corresponding to 27 human gestational weeks) were treated for 14 days with intravenous (i.v.) FG-4095, a PHD inhibitor. Notably, 77% of diminished total alveolar surface area in untreated controls was recovered by FG-4095 treatment. Functional significance of the structural changes was indicated by improved oxygenation and lung compliance in FG-4095-treated newborns. Surfactant proteins B and C and saturated phosphatidylcholine were unchanged. Incidence of spontaneous ductus arteriosus closure was increased, likely contributing to lower ratio of pulmonary to systemic blood flow in FG-4095 group. These findings indicate that HIF stimulation by PHD inhibition ameliorates pathological and physiological consequences of BPD.

Enhancement of angiogenic effectors through hypoxia-inducible factor in preterm primate lung in vivo.

Development of lung microvasculature is critical for distal airway formation. Both processes are arrested in the lungs of preterm newborns with bronchopulmonary dysplasia (BPD), a chronic form of lung disease. We hypothesized that activation of hypoxia-inducible factors (HIFs) augments lung vascular development. Pulmonary angiogenic factors were assessed by quantitative real-time PCR, Western blot, and immunohistochemistry in preterm baboons (125 days+14 days pro re nata O2 model) treated for 14 days with intravenous FG-4095, an inhibitor of prolyl hydroxylase domain-containing proteins (PHDs) that initiates HIF degradation. HIF-1alpha, but not HIF-2alpha, mRNA and protein were increased (8- and 3-fold, respectively) in FG-4095-treated baboons relative to untreated controls. Expression of PHD-1, -2, and -3 was unchanged. Of note, mRNA and/or protein for platelet-endothelial cell adhesion molecule 1 (PECAM-1) and vascular endothelial growth factor (VEGF) were increased by FG-4095. Moreover, PECAM-1-expressing capillary endothelial cells detected by immunohistochemistry were augmented in FG-4095-treated baboons to levels comparable to those in fetal age-matched controls. Alveolar septal cell expression of Ki67, a proliferative marker, and VEGF were similar in untreated controls and FG-4095-treated neonates. These results indicate that HIF stimulation by PHD inhibition enhances lung angiogenesis in the primate model of BPD.

Activation of hypoxia-inducible factors in hyperoxia through prolyl 4-hydroxylase blockade in cells and explants of primate lung.

Preterm neonates with respiratory distress syndrome (RDS) often develop a chronic form of lung disease called bronchopulmonary dysplasia (BPD), characterized by decreased alveolar and vascular development. Ventilator treatment with supraphysiological O2 concentrations (hyperoxia) contribute to the development of BPD. Hyperoxia down-regulates and hypoxia up-regulates many angiogenic factors in the developing lung. We investigated whether angiogenic responses could be augmented through enhancement of hypoxia-inducible factors 1alpha and 2alpha (HIF-1alpha and -2alpha, respectively) via blockade of prolyl hydroxylase domain-containing proteins (HIF-PHDs) in human microvascular endothelial cells from developing and adult lung, in epithelial A549 cells, and in fetal baboon explants in relative or absolute hyperoxia. PHD inhibitor (FG-4095) and positive control dimethyloxaloylglycine (DMOG), selective and nonselective HIF-PHD inhibitors, respectively, enhanced HIF-1alpha and -2alpha, vascular endothelial growth factor (VEGF), and platelet-endothelial cell adhesion molecule 1 expression in vitro in 95% and 21% O2. Furthermore, VEGF receptor fms-like tyrosine kinase 1 (Flt-1) was elevated, whereas kinase insert domain-containing receptor/fetal liver kinase 1 (KDR) was diminished in endothelial, but not epithelial, cells. Intracellular Flt-1 and KDR locations were unchanged by PHD blockade. Like VEGF, FG-4095 and DMOG increased angiogenesis in vitro, both in 95% and 21% O2, an effect that could be blocked through either Flt-1 or KDR. Notably, FG-4095 was effective in stimulating HIFs and VEGF also in fetal baboon lung explants. FG-4095 or DMOG treatment appeared to stimulate the feedback loop promoting HIF degradation in that PHD-2 and/or -3, but not PHD-1, were enhanced. Through actions characterized above, FG-4095 could have desirable effects in enhancing lung growth in BPD.

Novel D-ring analog of epigallocatechin-3-gallate inhibits tumor growth and VEGF expression in breast carcinoma cells.

The cancer chemopreventive activity of green tea and its major polyphenolic constituent, epigallocatechin-3-gallate (EGCG) have been attributed to its antioxidant, antiproliferative and antiangiogenic effects. Several new molecular targets for EGCG's anticarcinogenic activity have been proposed in the recent literature. However, the understanding of the molecular mechanisms of EGCG's activity in vivo have been confounded by its low oral bioavailability and low plasma levels. Studies of EGCG would be greatly aided by the availability of synthetic analogs of EGCG designed to understand the contributions of the A, B, and D-rings and the phenolic hydroxyl groups of EGCG to its molecular mechanisms of action. We recently reported the de novo synthesis of a D-ring analog of EGCG, with the objective of using such analogs to understand the molecular mechanisms of EGCG action. We report here the first studies with a synthetic D-ring analog of EGCG. We examined the ability of the synthetic D-ring analog to inhibit tumor cell proliferation in breast carcinoma cells. We also investigated the effect of the analog on stress-induced VEGF production in breast carcinoma cells using Northern analysis and quantitative RT-PCR. We report here that the synthetic D-ring analog inhibits breast cancer cell growth in vitro with potencies equivalent to those of EGCG. Our results also show that, like EGCG, the synthetic analog inhibits hypoxia- and serum starvation-induced production of VEGF mRNA in breast cancer cells. Such synthetic analogs are valuable for understanding the structure-function relationship of EGCG and identifying relevant mechanisms of the chemopreventive action of EGCG.