A simplified protocol for profiling heparin-contaminated circulating miRNAs: by microfluidic array.

Peripheral blood is a valuable, non-invasive source of biomarkers which include circulating miRNAs. Using microfluidic array-based techniques, miRNAs can be successfully measured in small amounts of blood plasma (< 0.5 mL) using cDNA pre-amplification. However, the use of heparin-based anticoagulants for blood collection hinders the detection of circulating miRNAs due to its inhibitory effect on PCR components. Although pre-treatment with heparinase have been shown to overcome heparin contamination in blood, its effect has not been described in array-based analyses or more sensitive applications with smaller sample volumes (i.e. 200 µL plasma) requiring pre-amplification. We show that the treatment of miRNA extracted from heparinised plasma with an optimised concentration of Bacteroides heparinase I prior to cDNA pre-amplification dramatically improves the number of detectable miRNA from 2 to 67 targets on the TaqMan® Array Human MicroRNA Cards. Furthermore, the titrated amount of heparinase (3 U) gave the best miRNA detection compared to those used in previous studies (6-24 U). This study provides novel data which demonstrates that heparinase treatment is compatible with protocols that involve pre-amplification of cDNA and microfluidic array-based techniques. This an improved methodology that permits miRNA-based biomarker analysis from small volume of heparinised plasma.

Regulator of G-protein signaling 5 controls blood pressure homeostasis and vessel wall remodeling.

RATIONALE: Regulator of G-protein signaling 5 (RGS5) modulates G-protein-coupled receptor signaling and is prominently expressed in arterial smooth muscle cells. Our group first reported that RGS5 is important in vascular remodeling during tumor angiogenesis. We hypothesized that RGS5 may play an important role in vessel wall remodeling and blood pressure regulation. OBJECTIVE: To demonstrate that RGS5 has a unique and nonredundant role in the pathogenesis of hypertension and to identify crucial RGS5-regulated signaling pathways. METHODS AND RESULTS: We observed that arterial RGS5 expression is downregulated with chronically elevated blood pressure after angiotensin II infusion. Using a knockout mouse model, radiotelemetry, and pharmacological inhibition, we subsequently showed that loss of RGS5 results in profound hypertension. RGS5 signaling is linked to the renin-angiotensin system and directly controls vascular resistance, vessel contractility, and remodeling. RGS5 deficiency aggravates pathophysiological features of hypertension, such as medial hypertrophy and fibrosis. Moreover, we demonstrate that protein kinase C, mitogen-activated protein kinase/extracellular signal-regulated kinase, and Rho kinase signaling pathways are major effectors of RGS5-mediated hypertension. CONCLUSIONS: Loss of RGS5 results in hypertension. Loss of RGS5 signaling also correlates with hyper-responsiveness to vasoconstrictors and vascular stiffening. This establishes a significant, distinct, and causal role of RGS5 in vascular homeostasis. RGS5 modulates signaling through the angiotensin II receptor 1 and major Gαq-coupled downstream pathways, including Rho kinase. So far, activation of RhoA/Rho kinase has not been associated with RGS molecules. Thus, RGS5 is a crucial regulator of blood pressure homeostasis with significant clinical implications for vascular pathologies, such as hypertension.

Expression profile and function of Wnt signaling mechanisms in malignant mesothelioma cells.

Malignant mesothelioma (MM) is an uncommon and particularly aggressive cancer associated with asbestos exposure, which currently presents an intractable clinical challenge. Wnt signaling has been reported to play a role in the neoplastic properties of mesothelioma cells but has not been investigated in detail in this cancer. We surveyed expression of Wnts, their receptors, and other key molecules in this pathway in well established in vitro mesothelioma models in comparison with primary mesothelial cultures. We also tested the biological response of MM cell lines to exogenous Wnt and secreted regulators, as well as targeting ß-catenin. We detected frequent expression of Wnt3 and Wnt5a, as well as Fzd 2, 4 and 6. The mRNA of Wnt4, Fzd3, sFRP4, APC and axin2 were downregulated in MM relative to mesothelial cells while LEF1 was overexpressed in MM. Functionally, we observed that Wnt3a stimulated MM proliferation while sFRP4 was inhibitory. Furthermore, directly targeting ß-catenin expression could sensitise MM cells to cytotoxic drugs. These results provide evidence for altered expression of a number of Wnt/Fzd signaling molecules in MM. Modulation of Wnt signaling in MM may prove a means of targeting proliferation and drug resistance in this cancer.

Synthesis and antimalarial evaluation of novel isocryptolepine derivatives.

A series of mono- and di-substituted analogues of isocryptolepine have been synthesized and evaluated for in vitro antimalarial activity against chloroquine sensitive (3D7) and resistant (W2mef) Plasmodium falciparum and for cytotoxicity (3T3 cells). Di-halogenated compounds were the most potent derivatives and 8-bromo-2-chloroisocryptolepine displayed the highest selectivity index (106; the ratio of cytotoxicity (IC(50)=9005 nM) to antimalarial activity (IC(50)=85 nM)). Our evaluation of novel isocryptolepine compounds has demonstrated that di-halogenated derivatives are promising antimalarial lead compounds.