Strong time dependence of the 76-gene prognostic signature for node-negative breast cancer patients in the TRANSBIG multicenter independent validation series.

PURPOSE: Recently, a 76-gene prognostic signature able to predict distant metastases in lymph node-negative (N(-)) breast cancer patients was reported. The aims of this study conducted by TRANSBIG were to independently validate these results and to compare the outcome with clinical risk assessment. EXPERIMENTAL DESIGN: Gene expression profiling of frozen samples from 198 N(-) systemically untreated patients was done at the Bordet Institute, blinded to clinical data and independent of Veridex. Genomic risk was defined by Veridex, blinded to clinical data. Survival analyses, done by an independent statistician, were done with the genomic risk and adjusted for the clinical risk, defined by Adjuvant! Online. RESULTS: The actual 5- and 10-year time to distant metastasis were 98% (88-100%) and 94% (83-98%), respectively, for the good profile group and 76% (68-82%) and 73% (65-79%), respectively, for the poor profile group. The actual 5- and 10-year overall survival were 98% (88-100%) and 87% (73-94%), respectively, for the good profile group and 84% (77-89%) and 72% (63-78%), respectively, for the poor profile group. We observed a strong time dependence of this signature, leading to an adjusted hazard ratio of 13.58 (1.85-99.63) and 8.20 (1.10-60.90) at 5 years and 5.11 (1.57-16.67) and 2.55 (1.07-6.10) at 10 years for time to distant metastasis and overall survival, respectively. CONCLUSION: This independent validation confirmed the performance of the 76-gene signature and adds to the growing evidence that gene expression signatures are of clinical relevance, especially for identifying patients at high risk of early distant metastases.     

The Growth Factor Midkine Antagonizes VEGF Signaling In Vitro and In Vivo

Midkine (MDK) is a heparin-binding growth factor involved in growth, survival, migration, and differentiation of various target cells and dysregulation of MDK signaling is implicated in a variety of inflammatory diseases and cancers. Although MDK has been reported to act on endothelial cells and to have proangiogenic effects, the exact role of MDK in angiogenesis is poorly defined. Here, we report that MDK is actually a modulator of angiogenesis and that it can abrogate the vascular endothelial growth factor A (VEGF-A)-induced proliferation of human microvascular endothelial cells in vitro through the downregulation of proangiogenic cytokines and through the upregulation of the antiangiogenic factor, tissue inhibitor of metalloproteinase 2. Phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR-2) and of downstream signaling molecules, such as phosphatidylinositol-3-kinase and mitogen-activated protein kinases, is also impaired. Moreover, MDK downregulates VEGF-A-induced neovascularization and vascular permeability in vivo. We propose a model in which MDK is a new modulator of the VEGF-A-VEGFR-2 axis.     

Elevation of arterial potassium during acute systemic hypoxia is abolished by alkalosis

BACKGROUND: Small elevations in plasma potassium evoke vasodilation in the peripheral circulation. Systemic hypoxia elevates arterial potassium and also modifies arterial pH. AIMS: We examined the interaction between pH and potassium in blood during systemic hypoxia and the effect of pH on the uptake/release of potassium in the peripheral tissues. METHODS: Anesthetized dogs were ventilated with air plus oxygen for normoxia or air plus nitrogen for hypoxia. Some animals received intravenous sodium bicarbonate to elevate pH by 0.1 units. Arterial plasma potassium concentration was measured in normoxia and hypoxia. A rat gracilis muscle was perfused with normoxic Krebs buffer and the potassium content of the venous outflow was compared during perfusion at pH 7.4, 6.8, or 7.8. RESULTS: In dogs with an arterial pH of 7.40-7.45, systemic hypoxia elevated the arterial potassium by 1 mmol/L. An arterial pH of 7.55 did not alter the basal potassium concentration, but it abolished the hypoxia-induced increase. In rat muscle, reduction of the perfusate pH from 7.4 to 6.8 reduced arterial perfusion pressure from 8.73 to 7.32 kPa and venous potassium from 6.6 to 5.2 mM. Elevation of perfusate pH to 7.8 decreased the arterial perfusion pressure from 8.44 to 6.95 kPa but did not affect venous potassium. CONCLUSIONS: The hypoxia-induced elevation of arterial potassium is abolished by increasing the pH to 7.55. This is not due to enhanced potassium uptake into peripheral tissues at high pH. Red blood cells are suggested as the most likely source of the potassium released in hypoxia.     

ILK as a potential marker gene to ascertain specific adenocarcinoma cell mRNA isolation from frozen prostate biopsy tissue sections

A major technical challenge related to gene expression profiling of tissue samples is the difficulty of procuring selected cell populations from tissues that by nature are heterogeneous, such as prostate tissue. In this study we have examined the expression of integrin-linked kinase (ILK) mRNA in prostate adenocarcinoma cells versus normal prostate epithelial cells in order to determine whether ILK could be used as a reference marker gene for prostate adenocarcinoma cell mRNA isolation. Using laser microdissection (LMD) technology and real-time PCR, together with immunohistochemistry, we have analyzed ILK mRNA expression in epithelial cells isolated from frozen prostate biopsy specimens as well as 4 prostate cell lines (RWPE-1, LNCaP, PC-3 and DU 145) and correlated ILK mRNA expression with ILK protein expression. We demonstrate that quantitative upregulation of ILK mRNA expression in prostate epithelial cells derived from prostate tissue correlated with ILK protein expression and with the histopathology diagnosis of prostate adenocarcinoma. We further show that the level of ILK overexpression was directly influenced by the method used to isolate prostate adenocarcinoma cells (bulk tissue versus LMD dissected cells). These data provide evidence that ILK mRNA is quantitatively upregulated in prostate adenocarcinoma cells versus normal epithelial cells and is therefore a useful internal reference gene marker to evaluate the quality of prostate adenocarcinoma cell derived mRNA used for large scale prostate cancer cDNA gene profiling.