Curcuminoids Inhibit Angiogenic Behaviors of Human Umbilical Vein Endothelial Cells via Endoglin/Smad1 Signaling.

BACKGROUND: Angiogenesis is primarily attributed to the excessive proliferation and migration of endothelial cells. Targeting the vascular endothelial growth factor (VEGF) is therefore significant in anti-angiogenic therapy. Although these treatments have not reached clinical expectations, the upregulation of alternative angiogenic pathways (endoglin/Smad1) may play a critical role in drug (VEGF-neutralizing agents) resistance. Enhanced endoglin expression following a VEGF-neutralizing therapy (semaxanib®) was noted in patients. Treatment with an endoglin-targeting antibody augmented VEGF expression in human umbilical vein endothelial cells (HUVECs). Therefore, approaches that inhibit both the androgen and VEGF pathways enhance the HUVECs cytotoxicity and reverse semaxanib resistance. The purpose of this study was to find natural-occurring compounds that inhibited the endoglin-targeting pathway. METHODS: Curcuminoids targeting endoglin were recognized from two thousand compounds in the Traditional Chinese Medicine Database@Taiwan (TCM Database@Taiwan) using Discovery Studio 4.5. RESULTS: Our results, obtained using cytotoxicity, migration/invasion, and flow cytometry assays, showed that curcumin (Cur) and demethoxycurcumin (DMC) reduced angiogenesis. In addition, Cur and DMC downregulated endoglin/pSmad1 phosphorylation. CONCLUSIONS: The study first showed that Cur and DMC demonstrated antiangiogenic activity via the inhibition of endoglin/Smad1 signaling. Synergistic effects of curcuminoids (i.e., curcumin and DMC) and semaxanib on HUVECs were found. This might be attributed to endoglin/pSmad1 downregulation in HUVECs. Combination treatment with curcuminoids and a semaxanib is therefore expected to reverse semaxanib resistance.

Effect of Sutellarin on Neurogenesis in Neonatal Hypoxia-Ischemia Rat Model: Potential Mechanisms of Action.

To investigate the therapeutic efficacy of Scutellarin (SCU) on neurite growth and neurological functional recovery in neonatal hypoxic-ischemic (HI) rats. Primary cortical neurons were cultured to detect the effect of SCU on cell viability of neurons under oxygen-glucose deprivation (OGD). Double immunofluorescence staining of Tuj1 and TUNEL then observed the neurite growth and cell apoptosis in vitro,and double immunofluorescence staining of NEUN and TUNEL was performed to examine the neuronal apoptosis and cell apoptosis in brain tissues after HI in vivo. Pharmacological efficacy of SCU was also evaluated in HI rats by neurobehavioral tests, triphenyl tetrazolium chloride staining, Hematoxylin and eosin staining and Nissl staining. Astrocytes and microglia expression in damaged brain tissues were detected by immunostaining of GFAP and Iba1. A quantitative real-time polymerase chain reaction and western blot were applied to investigate the genetic expression changes and the protein levels of autophagy-related proteins in the injured cortex and hippocampus after HI. We found that SCU administration preserved cell viability, promoted neurite outgrowth and suppressed apoptosis of neurons subjected to OGD both in vitroand in vivo. Meanwhile, 20 mg/kg SCU treatment improved neurological functions and decreased the expression of astrocytes and microglia in the cortex and hippocampus of HI rats. Additionally, SCU treatment depressed the elevated levels of autophagy-related proteins and the p75 neurotrophin receptor (p75NTR) in both cortex and hippocampus. This study demonstrated the potential therapeutic efficacy of SCU by enhancing neurogenesis and restoring long-term neurological dysfunctions, which might be associated with p75NTR depletion in HI rats.

The mechanism of activated platelet-rich plasma supernatant promotion of hair growth by cultured dermal papilla cells.

BACKGROUND: Platelet-rich plasma (PRP) is an innovative treatment of androgenic alopecia in the early stages of development, and its mechanism of action is not well investigated. OBJECTIVE: The objective was to investigate the promotion of hair growth by activated PRP supernatant in cultured dermal papilla cells (DPCs). METHODS AND MATERIALS: Human DPCs were isolated and grown in culture with or without activated PRP supernatant. The expression of phosphorylated growth factor receptors (GFRs) in cultured DPCs was assayed by immunofluorescence and Western blotting. Signal pathways mediated by GFRs were identified by a human phosphokinase array. RESULTS: Activated PRP supernatant enhanced the expression of phosphorylated fibroblast growth factor receptor (FGFR)-1, platelet-derived growth factor receptor (PDGFR)α, and PDGFRß in cultured DPCs. Activated PRP supernatant activated mitogen-activated protein kinase (MAPK) and protein kinase B (Akt) signaling pathways that promoted proliferation of DPCs. Downregulation of glycogen synthase kinase-3 was consistent with the involvement of Wnt signaling. Activated PRP supernatant increased the hair growth promoting ability of DPCs by activating the Wnt signaling pathway. CONCLUSION: Autologous activated PRP supernatant promoted signaling in cultured human DPCs via pathways known to be involved in hair growth. The results warrant further study of PRP for the clinical treatment of androgenic alopecia.

Effect of electroacupuncture on the expression of agrin and acetylcholine receptor subtypes in rats with tibialis anterior muscular atrophy induced by sciatic nerve injection injury.

OBJECTIVE: To investigate the effects of electroacupuncture (EA) on mRNA and protein expression of agrin, acetylcholine receptor (AChR)-ε and AChR-γ in a rat model of tibialis anterior muscle atrophy induced by sciatic nerve injection injury, and to examine the underlying mechanism of action. METHODS: Fifty-four adult Sprague-Dawley rats were divided into four groups: healthy control group (CON, n=6); sciatic nerve injury group (SNI, n=24), comprising rats euthanased at 1, 2, 4 and 6 weeks, respectively, after penicillin injection-induced SNI (n=6 each); CON+EA group (n=12), comprising healthy rats euthanased at 4 and 6 weeks (after 2 and 4 weeks, respectively, of EA at GB30 and ST36); and SNI+EA group, comprising rats euthanased at 4 and 6 weeks (after 2 and 4 weeks, respectively, of EA). The sciatic nerve functional index (SFI), tibialis anterior muscle weight, muscle fibre cross-sectional area (CSA), and changes in agrin, AChR-ε, and AChR-γ expression levels were analysed. RESULTS: Compared with the control group (CON), SNI rats showed decreased SFI. The weight of the tibialis anterior muscle and muscle fibre CSA decreased initially and recovered slightly over time. mRNA/protein expression of agrin and AChR-ε were downregulated and AChR-γ expression was detectable (vs zero expression in the CON/CON+EA groups). There were no significant differences in CON+EA versus CON groups. However, the SNI+EA group exhibited significant improvements compared with the untreated SNI group (p<0.05). CONCLUSIONS: EA may alleviate tibialis anterior muscle atrophy induced by sciatic nerve injection injury by upregulating agrin and AChR-ε and downregulating AChR-γ.

Bufalin loaded biotinylated chitosan nanoparticles: an efficient drug delivery system for targeted chemotherapy against breast carcinoma.

Bufalin is a traditional oriental medicine which is known to induce apoptosis in many tumor cells, and it is thus considered as a new anticancer therapeutic. By now, most of the studies of bufalin are in vitro, however in vivo evaluations of its therapeutic efficacy are less and are in great demand for its development toward anticancer drug. One of the problems probably hampering the development of bufalin is the lack of tumor selectivity, which may reduce the therapeutic effect as well as showing side effects. To overcome this drawback, in this study, we designed a tumor-targeted drug delivery system of bufalin based on enhanced permeability and retention (EPR) effect, by using biotinylated chitosan, resulting in bufalin encapsulating nanoparticles (Bu-BCS-NPs) with mean hydrodynamic size of 171.6 nm, as evidenced by dynamic light scattering and transmission electron microscope. Bu-BCS-NPs showed a relative slow and almost linear release of bufalin, and about 36.8% of bufalin was released in 24 h when dissolved in sodium phosphate buffer. Compared to native bufalin, Bu-BCS-NPs exhibited a stronger cytotoxicity against breast cancer MCF-7 cells (IC50 of 0.582 µg/ml vs 1.896 µg/ml of native bufalin). Similar results were also obtained in intracellular reactive oxygen species production, apoptosis induction, and decrease in mitochondria membrane potential. These results may contribute to the rapid intracellular uptake of nanoparticles, partly benefiting from the highly expressed biotin receptors in tumor cells. In vivo studies using MCF-7 tumor models in nude mice confirmed the remarkable therapeutic effect of Bu-BCS-NPs. These findings suggest the potential of Bu-BCS-NPs as an anticancer drug with tumor targeting property.

Impacts of maternal selenium supply and nutritional plane on visceral tissues and intestinal biology in 180-day-old offspring in sheep.

Objectives were to investigate the effects of maternal Se supply and nutritional plane during gestation on offspring visceral tissues and indices of intestinal growth, vascularity, and function at 180 d of age. Rambouillet ewe lambs (n = 82, approximately 240 d of age; 52 ± 0.8 kg BW at breeding) were allocated to a 2 × 3 factorial arrangement of treatments. Treatments included dietary Se [adequate Se (ASe, 9.5 µg/kg BW) or high Se (HSe, 81.8 µg/kg BW)] initiated at breeding and nutritional plane [60% (restricted, RES), 100% (control, CON), and 140% (high, HI) of requirements] initiated at d 50 of gestation. Ewes were fed pelleted diets and housed individually indoors. At parturition, lambs were immediately removed and fed artificial colostrum for the first 20 h followed by ad libitum access to milk replacer. At 180 ± 2 d of age, lambs were euthanized and tissues were harvested. Birth weight was affected by nutritional treatments (P < 0.001), with decreased birth weight in RES and HI compared with CON. Offspring from RES and HI ewes had decreased (P = 0.07) blood volume compared with CON, and those born to HSe ewes had increased (P < 0.04) total visceral adiposity. Within offspring from CON ewes, those from HSe ewes had greater (P < 0.02) intestinal mass compared with ASe ewes. Within offspring from HSe ewes, both RES and HI had reduced (P ≤ 0.05) intestinal mass compared with CON. Jejunal capillary area density was greater (P = 0.08) in offspring from ewes fed HSe compared with ASe. In addition, area per capillary was greater (P ≤ 0.09) in CON compared with RES. Maternal nutritional plane tended (P ≤ 0.11) to alter total small intestinal vascularity, with lambs from CON being greater than RES. Expression of most mRNA for measured angiogenic factors and receptors was not altered (P ≤ 0.13) by maternal treatments; however, expression of glucagon-like peptide-2 (GLP-2) was decreased (P = 0.07) in offspring from RES compared with CON ewes. Offspring from ewes fed HI diets had increased (P = 0.08) jejunal mucosal maltase activity. In conclusion, maternal Se supply and nutritional plane during gestation resulted in measurable changes in offspring visceral tissues and intestinal biology, including perirenal fat, blood volume, intestinal mass, total jejunal crypt cell proliferation, area per capillary in jejunal villi, GLP-2 mRNA expression, and maltase activity at 180 d. Additional work is needed to determine impacts on intestinal function and nutrient uptake.

Molecular mechanisms of curcumin action: gene expression.

Curcumin derived from the tropical plant Curcuma longa has a long history of use as a dietary agent, food preservative, and in traditional Asian medicine. It has been used for centuries to treat biliary disorders, anorexia, cough, diabetic wounds, hepatic disorders, rheumatism, and sinusitis. The preventive and therapeutic properties of curcumin are associated with its antioxidant, anti-inflammatory, and anticancer properties. Extensive research over several decades has attempted to identify the molecular mechanisms of curcumin action. Curcumin modulates numerous molecular targets by altering their gene expression, signaling pathways, or through direct interaction. Curcumin regulates the expression of inflammatory cytokines (e.g., TNF, IL-1), growth factors (e.g., VEGF, EGF, FGF), growth factor receptors (e.g., EGFR, HER-2, AR), enzymes (e.g., COX-2, LOX, MMP9, MAPK, mTOR, Akt), adhesion molecules (e.g., ELAM-1, ICAM-1, VCAM-1), apoptosis related proteins (e.g., Bcl-2, caspases, DR, Fas), and cell cycle proteins (e.g., cyclin D1). Curcumin modulates the activity of several transcription factors (e.g., NF-κB, AP-1, STAT) and their signaling pathways. Based on its ability to affect multiple targets, curcumin has the potential for the prevention and treatment of various diseases including cancers, arthritis, allergies, atherosclerosis, aging, neurodegenerative disease, hepatic disorders, obesity, diabetes, psoriasis, and autoimmune diseases. This review summarizes the molecular mechanisms of modulation of gene expression by curcumin.

Versatile and efficient targeting using a single nanoparticulate platform: application to cancer and Alzheimer's disease.

A versatile and efficient functionalization strategy for polymeric nanoparticles (NPs) has been reported and successfully applied to PEGylated, biodegradable poly(alkyl cyanoacrylate) (PACA) nanocarriers. The relevance of this platform was demonstrated in both the fields of cancer and Alzheimer's disease (AD). Prepared by copper-catalyzed azide-alkyne cycloaddition (CuAAC) and subsequent self-assembly in aqueous solution of amphiphilic copolymers, the resulting functionalized polymeric NPs exhibited requisite characteristics for drug delivery purposes: (i) a biodegradable core made of poly(alkyl cyanoacrylate), (ii) a hydrophilic poly(ethylene glycol) (PEG) outer shell leading to colloidal stabilization, (iii) fluorescent properties provided by the covalent linkage of a rhodamine B-based dye to the polymer backbone, and (iv) surface functionalization with biologically active ligands that enabled specific targeting. The construction method is very versatile and was illustrated by the coupling of a small library of ligands (e.g., biotin, curcumin derivatives, and antibody), resulting in high affinity toward (i) murine lung carcinoma (M109) and human breast cancer (MCF7) cell lines, even in a coculture environment with healthy cells and (ii) the ß-amyloid peptide 1-42 (Aß(1-42)), believed to be the most representative and toxic species in AD, both under its monomeric and fibrillar forms. In the case of AD, the ligand-functionalized NPs exhibited higher affinity toward Aß(1-42) species comparatively to other kinds of colloidal systems and led to significant aggregation inhibition and toxicity rescue of Aß(1-42) at low molar ratios.

Evolving molecular mechanism-based strategies for control of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a major cause of cancer mortality worldwide. Unresectable or metastatic HCC has a poor prognosis, and systemic cytotoxic chemotherapy has failed to show a substantial benefit for patients with HCC. However, there has been increasing interest in developing novel molecularly targeted agents in HCC due to the accumulation of knowledge of cell signaling and molecular carcinogenesis. Furthermore, some of these agents have proven to be efficacious in other traditionally challenging carcinomas, such as renal cell carcinoma. Recently, a phase III, randomized, placebo-controlled trial demonstrated that sorafenib, an oral multikinase inhibitor of the vascular endothelial growth factor receptor and Ras kinase, improves overall survival (OS) in patients with advanced HCC. This seminal study described the first agent to improve OS in HCC and began a new era of molecule-targeted cancer therapies. Currently, many novel molecularly targeted agents are under evaluation in clinical trials. In this review, we comprehensively summarize the molecular pathogenesis, targets, and signal transduction pathways involved in HCC. We also detail the current status of molecularly targeted agents that are under clinical development in advanced HCC, including the mechanisms of action of these agents.

Epigallocatechin-3-gallate inhibits paracrine and autocrine hepatocyte growth factor/scatter factor-induced tumor cell migration and invasion.

Aberrant activation of hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, Met, is involved in the development and progression of many human cancers. In the cell-based screening assay, (-)epigallocatechin-3-gallate (EGCG) inhibited HGF/SF-Met signaling as indicated by its inhibitory activity on HGF/SF-induced cell scattering and uPA activation (IC50=15.8 microgram/ml). Further analysis revealed that EGCG at low doses specifically inhibited HGF/SF-induced tyrosine phosphorylation of Met but not epidermal growth factor (EGF)-induced phosphorylation of EGF receptor (EGFR). On the other hand, high-dose EGCG decreased both Met and EGFR proteins. We also found that EGCG did not act on the intracellular portion of Met receptor tyrosine kinase, i.e., it inhibited InlB-dependent activation of Met but not NGF-induced activation of Trk-Met hybrid receptor. This inhibition decreased HGF-induced migration and invasion by parental or HGF/SF-transfected B16F10 melanoma cells in vitro in either a paracrine or autocrine manner. Furthermore, EGCG inhibited the invasion/metastasis of HGF/SF-transfected B16F10 melanoma cells in mice. Our data suggest the possible use of EGCG in human cancers associated with dysregulated paracrine or autocrine HGF/SF-Met signaling.

An adjacent arginine, and the phosphorylated tyrosine in the c-Met receptor target sequence, dictates the orientation of c-Cbl binding.

Previously, we have demonstrated that the tyrosine phosphorylated hepatocyte growth factor receptor (Met) binds to the c-Cbl phosphotyrosine-recognition, tyrosine kinase binding (TKB) domain in a reverse orientation compared to other c-Cbl binding partners. A Met peptide with the DpYR motif changed to RpYD (MetRD) retains a similar TKB binding affinity as the native Met peptide. However, the TKB: MetRD complex crystal structure reveals a complete reversal of the binding orientation. Collated data indicates that both binding and orientation is dictated by the phosphorylated tyrosine and an adjacent arginine forming intra-peptide hydrogen bonds and aligning unidirectionally with complementary charges in the phosphotyrosine binding pocket of c-Cbl.

The effect of secoisolariciresinol diglucoside and flaxseed oil, alone and in combination, on MCF-7 tumor growth and signaling pathways.

Flaxseed (FS), an oilseed containing high amounts of the phytoestrogen lignan, secoisolariciresinol diglucoside (SDG), and n-3 fatty acid, alpha-linolenic acid-rich oil (FO), has been shown to inhibit the growth of established human breast tumors (MCF-7) in ovariectomized (OVX) athymic mice. However, the major FS component responsible for this effect and the mechanism(s) of its action are unclear. Hence, this study determined, in a 2 x 2 factorial design, the effect of SDG and FO, alone or in combination, on the growth of established human estrogen receptor positive (ER+) breast tumors and the potential mechanism(s) of its action. OVX mice with established ER+ human breast tumors (MCF-7) were treated for 8 wk with basal diet (BD, control) or BD supplemented with SDG (1 g/kg), FO (38.5 g/kg), or SDG + FO. All treatments reduced the tumor growth, but SDG had the greatest effect primarily through reducing tumor cell proliferation rather than increasing apoptosis. SDG had a main effect in the reduction of PS2, BCL2, and IGF-1R mRNA expression, whereas FO had a main effect only in PAKT reduction. SDG alone also lowered the ERalpha, ERbeta, EGFR, BCL2 mRNA, and PMAPK protein, indicating that its effect involves the modulation of the ER- and growth factor receptor-mediated signaling pathways.

Identification of c-Src as a potential therapeutic target for gastric cancer and of MET activation as a cause of resistance to c-Src inhibition.

Therapeutic strategies that target c-Src hold promise for a wide variety of cancers. We have now investigated both the effects of dasatinib, which inhibits the activity of c-Src and several other kinases, on cell growth as well as the mechanism of dasatinib resistance in human gastric cancer cell lines. Immunoblot analysis revealed the activation of c-Src at various levels in most gastric cancer cell lines examined. Dasatinib inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) and induced G(1) arrest, as revealed by flow cytometry, in a subset of responsive cell lines. In other responsive cell lines, dasatinib inhibited both ERK and AKT phosphorylation and induced apoptosis, as revealed by an increase in caspase-3 activity and cleavage of poly(ADP-ribose) polymerase. Depletion of c-Src by RNA interference also induced G(1) arrest or apoptosis in dasatinib-responsive cell lines, indicating that the antiproliferative effect of dasatinib is attributable to c-Src inhibition. Gastric cancer cell lines positive for the activation of MET were resistant to dasatinib. Dasatinib had no effect on ERK or AKT signaling, whereas the MET inhibitor PHA-665752 induced apoptosis in these cells. The subsets of gastric cancer cells defined by a response to c-Src or MET inhibitors were distinct and nonoverlapping. Our results suggest that c-Src is a promising target for the treatment of gastric cancer and that analysis of MET amplification might optimize patient selection for treatment with c-Src inhibitors.

Dietary flaxseed lignan or oil combined with tamoxifen treatment affects MCF-7 tumor growth through estrogen receptor- and growth factor-signaling pathways.

This study aimed to elucidate which component of flaxseed, i.e. secoisolariciresinol diglucoside (SDG) lignan or flaxseed oil (FO), makes tamoxifen (TAM) more effective in reducing growth of established estrogen receptor positive breast tumors (MCF-7) at low circulating estrogen levels, and potential mechanisms of action. In a 2 x 2 factorial design, ovariectomized athymic mice with established tumors were treated for 8 wk with TAM together with basal diet (control), or basal diet supplemented with SDG (1 g/kg diet), FO (38.5 g/kg diet), or combined SDG and FO. SDG and FO were at levels in 10% flaxseed diet. Palpable tumors were monitored and after animal sacrifice, analyzed for cell proliferation, apoptosis, ER-mediated (ER-alpha, ER-beta, trefoil factor 1, cyclin D1, progesterone receptor, AIBI), growth factor-mediated (epidermal growth factor receptor, human epidermal growth factor receptor-2, insulin-like growth factor receptor-1, phosphorylated mitogen activated protein kinase, PAKT, BCL2) signaling pathways and angiogenesis (vascular endothelial growth factor). All treatments reduced the growth of TAM-treated tumors by reducing cell proliferation, expression of genes, and proteins involved in the ER- and growth factor-mediated signaling pathways with FO having the greatest effect in increasing apoptosis compared with TAM treatment alone. SDG and FO reduced the growth of TAM-treated tumors but FO was more effective. The mechanisms involve both the ER- and growth factor-signaling pathways.

Plant phenolics in the prevention and treatment of cancer.

Epidemiological studies indicate that populations consuming high levels of plant derived foods have low incidence rates of various cancers. Recent findings implicate a variety of phytochemicals, including phenolics, in these anticancer properties. Both monophenolic and polyphenolic compounds from a large variety of plant foods, spices and beverages have been shown to inhibit or attenuate the initiation, progression and spread of cancers in cells in vitro and in animals in vivo. The cellular mechanisms that phenolics modulate to elicit these anticancer effects are multi-faceted and include regulation of growth factor-receptor interactions and cell signaling cascades, including kinases and transcription factors, that determine the expression of genes involved in cell cycle arrest, cell survival and apoptosis or programmed cell death. A major focus has been the inhibitory effects of phenolics on the stress-activated NF-KB and AP-1 signal cascades in cancer cells which are regarded as major therapeutic targets. Phenolics can enhance the body's immune system to recognize and destroy cancer cells as well as inhibiting the development of new blood vessels (angiogenesis) that is necessary for tumour growth. They also attenuate adhesiveness and invasiveness of cancer cells thereby reducing their metastatic potential. Augmentation of the efficacy ofstandard chemo- and radiotherapeutic treatment regimes and the prevention of resistance to these agents is another important effect of plant phenolics that warrants further research. Plant phenolics appear to have both preventative and treatment potential in combating cancer and warrant further, in-depth research. It is interesting that these effects of plant phenolics on cancer inhibition resemble effects reported for specific fatty acids (omega-3 PUFA, conjugated linoleic acids). Although phenolic effects in cells in vitro and in animal models are generally positive, observations from the less numerous human interventions are less clear. This is surprising given the positive epidemiological data and may relate to mixed diets and synergistic interactions between compounds or the bioavailability of individual compounds. Much of the work in vitro with phenolic compounds has utilized concentrations higher than the amount that can be obtained from the diet suggesting a role of fortified, functional foods in cancer suppression.

New drugs for the treatment of hepatocellular carcinoma.

Treatment of hepatocellular carcinoma has dramatically changed in the last years. The better knowledge of the molecular mechanisms responsible of tumor initiation and progression has allowed the development of molecular targeted therapies that specifically block the disrupted pathways. Among all these new agents, Sorafenib is the only one that has shown efficacy in terms of survival in advanced stage in two randomized, double-blind, controlled trials. The positive result of these two trials are the proof of the efficacy of molecular targeted therapies in hepatocellular carcinoma and opens the door to multipathway blockade and the use of these targeted therapies in the adjuvant setting. Other agents have shown promising results in phase 1-2 trials but further studies are needed to demonstrate their efficacy. In the next years, efforts should be directed to identifying genomic and proteomic profiling that will help us to assess the prognosis and to define what treatment benefits whom, ultimately giving way to personalized medicine.

New ways to target old receptors.

Numerous important drugs target cytokines and growth factors or their receptors. Our understanding of the molecular mechanisms governing receptor activation and signaling has lagged in key areas, however, limiting drug discovery efforts to relatively few basic strategies. Recently, substantial progress has been made on several aspects of this problem. These include improved methods for establishing the mechanism of receptor activation, a clearer understanding of the biochemical basis for differential signaling by ligands that act through a common receptor, new methods for measuring the affinities of steps in receptor activation on live cells, and progress toward a systems level understanding of receptor signaling. These advances are providing a new understanding of the function of these receptors that presents opportunities for the development of improved drugs.

New agents in development for breast cancer.

PURPOSE OF REVIEW: This review summarizes the continuing value of some therapeutic drugs and new agents under development for the treatment of breast cancer. RECENT FINDINGS: Overexpression and activation of various growth factor receptors occurs frequently in human breast cancer. Therapeutic approaches mainly involve the epidermal growth factor receptor family, insulin-like growth factor receptor and vascular endothelial growth factor receptor. Therapeutic agents targeting these receptors include the monoclonal antibodies trastuzumab and pertuzumab, and the small-molecule inhibitors gefitinib and erlotinib. Other small-molecule and dual inhibitors are in development, some of which have been demonstrated to have higher efficacy in the treatment of breast cancer. The selective estrogen receptor modulators and aromatase inhibitors continue to be valuable in the endocrine therapy of breast cancer. These drugs have been shown to have higher efficacy than conventional therapy agents, and to have extensive potential, especially in the treatment of postmenopausal women with advanced breast cancer. SUMMARY: Approved agents including epidermal growth factor receptor-targeted inhibitor, selective estrogen receptor modulators and aromatase inhibitors continue to be valuable in treating breast cancer. To overcome the acquired resistance caused by these agents and to enhance the therapy effect, the development of new and specific dual inhibitors targeting various growth factor receptors will be important in the future.

Tea catechins inhibit angiogenesis in vitro, measured by human endothelial cell growth, migration and tube formation, through inhibition of VEGF receptor binding.

We have investigated whether tea catechins (EC, ECg, EGC, EGCg) have any inhibitory effects on angiogenesis and which step they affect during the process. The effects of catechins were tested on in vitro models of angiogenesis, namely, growth, migration and tube formation of human umbilical vein endothelial cells. All four catechins inhibited angiogenesis in vitro in the three different bioassays with concentrations ranging from 1.56 to 100 microM. Among the four catechins tested, epigallocatechin gallate (EGCg) was the most effective in inhibiting angiogenesis in all three assays. When these four catechins were tested on VEGF binding assay, only EGCg inhibited the binding of VEGF, a major angiogenesis inducing factor, to endothelial cells in a concentration dependent manner. These results indicate that while all four tea catechins inhibit the process of angiogenesis, EGCg alone can reduce the binding of VEGF to its receptors and thus affects the downstream signaling.

Dissection of angiogenic signaling in zebrafish using a chemical genetic approach.

Striking homology between signaling molecules in zebrafish and humans suggests that compounds known to inhibit human kinases may enable a chemical genetic approach to dissect signaling pathways in the zebrafish embryo. We tested this hypothesis using a vascular endothelial growth factor receptor inhibitor, PTK787/ZK222584. Zebrafish embryos treated with this compound lacked all major blood vessels. Overexpression of AKT/PKB, a putative effector of vascular endothelial growth factor signaling, allowed blood vessels to form in the presence of drug. Endothelial cell apoptosis induced by the drug is prevented by increasing AKT/PKB activity, thus establishing the physiological relevance of AKT/PKB in the angiogenic process. This approach allowed us to examine the effects of blood flow and the role of endothelial signals in organogenesis.