ErbB2 is a ligand-less member of the ErbB receptor family that functions as a coreceptor with EGFR, ErbB3, and ErbB4. Here, we describe an approach to target ErbB2's role as a coreceptor using a monoclonal antibody, 2C4, which sterically hinders ErbB2's recruitment into ErbB ligand complexes. Inhibition of ligand-dependent ErbB2 signaling by 2C4 occurs in both low- and high-ErbB2-expressing systems. Since the ErbB3 receptor contains an inactive tyrosine kinase domain, 2C4 is very effective in blocking heregulin-mediated ErbB3-ErbB2 signaling. We demonstrate that the in vitro and in vivo growth of several breast and prostate tumor models is inhibited by 2C4 treatment.

Neuronal injury in ischemic stroke is partly mediated by cytotoxic reactive oxygen species. Although the antioxidant ascorbic acid (AA) or vitamin C does not penetrate the blood-brain barrier (BBB), its oxidized form, dehydroascorbic acid (DHA), enters the brain by means of facilitative transport. We hypothesized that i.v. DHA would improve outcome after stroke because of its ability to cross the BBB and augment brain antioxidant levels. Reversible or permanent focal cerebral ischemia was created by intraluminal middle cerebral artery occlusion in mice treated with vehicle, AA, or DHA (40, 250, or 500 mg͞kg), either before or after ischemia. Given before ischemia, DHA caused dose-dependent increases in postreperfusion cerebral blood flow, with reductions in neurological deficit and mortality. In reperfused cerebral ischemia, mean infarct volume was reduced from 53% and 59% in vehicle-and AA-treated animals, respectively, to 15% in 250 mg͞kg DHAtreated animals (P < 0.05). Similar significant reductions occurred in nonreperfused cerebral ischemia. Delayed postischemic DHA administration after 15 min or 3 h also mediated improved outcomes. DHA (250 mg͞kg or 500 mg͞kg) administered at 3 h postischemia reduced infarct volume by 6-to 9-fold, to only 5% with the highest DHA dose (P < 0.05). In contrast, AA had no effect on infarct volumes, mortality, or neurological deficits. No differences in the incidence of intracerebral hemorrhage occurred. Unlike exogenous AA, DHA confers in vivo, dose-dependent neuroprotection in reperfused and nonreperfused cerebral ischemia at clinically relevant times. As a naturally occurring interconvertible form of AA with BBB permeability, DHA represents a promising pharmacological therapy for stroke based on its effects in this model of cerebral ischemia.

Early events included a decrease in androgen receptor expression, followed by a short-term increase in expression of the p53 and p21/WAF1 proteins and a marked decrease in the Ki67 proliferative index. Mid-to-late events included progressive and sustained increases in p27 and p16 protein expression, a decrease in retinoblastoma protein expression, and an increase in the transcription factor E2F1. Changes in apoptosis (programmed cell death) were not observed at any time after androgen withdrawal. These data suggest that androgen withdrawal results in a cell stress response, in which increased p53 protein produces a cell cycle arrest, without activation of p53-mediated apoptosis. The proliferative index is further decreased through the action of the cyclin-dependent kinase inhibitors p27 and p16. Androgen-independent sublines emerged 80-400 days after androgen withdrawal, and these sublines had variable growth phenotypes but were associated with mdm2 protein overexpression and increased expression of cyclin D1. These results indicate that tumor regression in this human prostate cancer model is due to cell cycle arrest rather than to apoptosis and that the emergence of androgen independence is associated with a release from cell cycle arrest.

9needed; these are often laborious and not practical for high-throughput screening. In order to develop a rapid automated mutation detection method, we have evaluated denaturing high-performance liquid chromatography for detection of TP53 mutations in tumor tissue. The specificity and sensitivity of the method were compared to those of denaturing gradient gel electrophoresis through testing on standard-quality DNA preparations as well as on DNA extracted from formalin-fixed, paraffin-embedded tissue sections. Amler, Lukas[8]Functional dissection of transcriptional profiles in androgen-dependent andindependent prostate cancer Using microarray analysis, we have measured changes in gene expression that occurred during the evolution of a primary prostate cancer xenograft, CWR22, from normalcy to relapsed, androgen-independent growth following androgen deprivation therapy. Rather than relying on simple pairwise comparison of the data between successive biological states (for example, normal versus tumor), we clustered the expression data on the basis of behavior in multiple biological states, representative of the entire process of prostate cancer progression. By examining the data in the context of different proliferative conditions, before and after hormonal manipulation in the xenograft model, we could identify groups of genes associated with proliferation, metabolism, hormone responsiveness and malignant transformation, as well as a small number of genes directly associated with androgen-independent growth. Our results imply that the evolution to androgen independence is due, in part, to reactivation of the androgen-response pathway in the absence of androgens, but that this reactivation is probably incomplete. Amler, Lukas [9]Dysregulated expression of androgenresponsive and nonresponsive genes in the androgen-independent prostate cancer xenograft model, CWR22-R Treatment of metastatic prostate cancer with androgen ablation often elicits dramatic tumor regressions, but the response is rarely complete, making clinical recurrence inevitable with time. To gain insight into therapy-related progression, we used microarray analysis to monitor changes in gene expression that occurred following androgen starvation of an androgen-dependent prostate tumor xenograft, CWR22, and the emergence of an androgen-independent tumor, CWR22-R. Androgen deprivation arrested the growth of CWR22 cells, as evidenced by decreased expression of genes encoding cell cycle components and basal cell metabolism, respiration and transcription, as well as the induced expression of putative negative regulatory genes that may act to sustain cells in a nonproliferative state. Evolution of androgen-independent growth and proliferation, represented by CWR22-R, was associated with a re-entry into the active cell cycle and the upregulation of several genes that were expressed at low levels or absent in the androgen-dependent tumor. Restoration of androgen to mice bearing androgenindependent CWR22-R tumors induced, augmented or repressed the expression ...

Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

These results identify CVS-3983 as a potent inhibitor of AI prostate cancer cell invasion in vitro and established xenograft tumor growth in vivo.

The Ron receptor tyrosine kinase plays a regulatory role in the inflammatory response to acute lung injury induced by intranasal administration of bacterial lipopolysaccharide (LPS). Previously, we have showen that mice with a targeted deletion of the tyrosine kinase (TK) signaling domain of the Ron receptor exhibited more severe lung injury in response to intranasal LPS administration as evidenced by increased leakage of albumin in the lungs and a greater thickening of the alveolar septae compared to wild-type mice. In addition, lung injury in the Ron TK deficient (TK−/−) mice was associated with increased activation of the transcription factor, nuclear factor kappaB (NF-κB) and significantly increased intrapulmonary expression of tumor necrosis factor alpha (TNFα). TNFα, a multifunctional pro-inflammatory cytokine, is a central mediator in several disease states including rheumatoid arthritis and sepsis. Based on the observation that TNFα production is increased in the Ron TK−/− mice and that macrophages are a major source of this cytokine, we hypothesized that the alterations observed in Ron TK−/− mice may be due, in part, to Ron signaling specifically in alveolar macrophages. To test this hypothesis, wild-type and Ron TK−/− primary alveolar macrophages and the murine alveolar macrophage cell line, MH-S, were used to examine the effects of Ron activation on LPS-induced TNFα production and NK-κB activity. Here, we report that Ron is expressed on alveolar macrophages and MH-S cells. Activation of Ron by its ligand, hepatocyte growth factor-like protein (HGFL), decreases TNFα production in alveolar macrophages following LPS challenge. Decreased TNFα is associated with HGFL-induced decreases in NF-κB activation and increases in the NF-κB inhibitory protein, IκB. We also provide the first evidence for Ron as a negative regulator of Adam17, the metalloprotease involved in TNFα processing. . These results indicate that Ron plays a critical role in regulation of alveolar macrophage signaling, and validates this receptor as a target in TNFα-mediated pulmonary pathologies.

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