Evgeniy Panzhinskiy

Isoliquiritigenin, a natural anti-oxidant, selectively inhibits the proliferation of prostate cancer cells

1. Isoliquiritigenin (ISL) is a simple chalcone‐type flavonoid derived from liquorice compounds. It has been reported to have anti‐oxidative and antitumour activities. The aim of the present study was to investigate the antitumour effect of ISL on prostate cancer cells and to explore the possible signalling mechanisms involved.

Hypoxia induces unique proliferative response in adventitial fibroblasts by activating PDGFβ receptor-JNK1 signalling

AIMS Pulmonary hypertension (PH) is a devastating condition for which no disease-modifying therapies exist. PH is recognized as proliferative disease of the pulmonary artery (PA). In the experimental newborn calf model of hypoxia-induced PH, adventitial fibroblasts in the PA wall exhibit a heightened replication index. Because elevated platelet-derived growth factor β receptor (PDGFβ-R) signalling is associated with PH, we tested the hypothesis that the activation of PDGFβ-R contributes to fibroblast proliferation and adventitial remodelling in PH. METHODS AND RESULTS Newborn calves were exposed to either ambient air (P(B) = 640 mmHg) (Neo-C) or high altitude (P(B) = 445 mm Hg) (Neo-PH) for 2 weeks. PDGFβ-R phosphorylation was markedly elevated in PA adventitia of Neo-PH calves as well as in cultured PA fibroblasts isolated from Neo-PH animals. PDGFβ-R activation with PDGF-BB stimulated higher replication in Neo-PH cells compared with that of control fibroblasts. PDGF-BB-induced proliferation was dependent on reactive oxygen species generation and extracellular signal-regulated kinase1/2 activation in both cell populations; however, only Neo-PH cell division via PDGFβ-R activation displayed a unique dependence on c-Jun N-terminal kinase1 (JNK1) stimulation as the blockade of JNK1 with SP600125, a pharmacological antagonist of the JNK pathway, and JNK1-targeted siRNA selectively blunted Neo-PH cell proliferation. CONCLUSIONS Our data strongly suggest that hypoxia-induced modified cells engage the PDGFβ-R-JNK1 axis to confer distinctively heightened proliferation and adventitial remodelling in PH.

Nox4-Generated Superoxide Drives Angiotensin II-Induced Neural Stem Cell Proliferation

Reactive oxygen species (ROS) have been reported to affect neural stem cell self-renewal and therefore may be important for normal development and may influence neurodegenerative processes when ROS activity is elevated. To determine if increasing production of superoxide, via activation of NADPH oxidase (Nox), increases neural stem cell proliferation, 100 nM angiotensin II (Ang II) - a strong stimulator of Nox - was applied to cultures of a murine neural stem cell line, C17.2. Twelve hours following a single treatment with Ang II, there was a doubling of the number of neural stem cells. This increase in neural stem cell numbers was preceded by a gradual elevation of superoxide levels (detected by dihydroethidium fluorescence) from the steady state at 0, 5, and 30 min and gradually increasing from 1 h to the maximum at 12 h, and returning to baseline at 24 h. Ang II-dependent proliferation was blocked by the antioxidant N-acetyl-L-cysteine. Confocal microscopy revealed the presence of two sources of intracellular ROS in C17.2 cells: (i) mitochondrial and (ii) extramitochondrial; the latter indicative of the involvement of one or more specific isoforms of Nox. Of the Nox family, mRNA expression for one member, Nox4, is abundant in neural stem cell cultures, and Ang II treatment resulted in elevation of the relative levels of Nox4 protein. SiRNA targeting of Nox4 mRNA reduced both the constitutive and Ang II-induced Nox4 protein levels and attenuated Ang II-driven increases in superoxide levels and stem cell proliferation. Our findings are consistent with our hypothesis that Ang II-induced proliferation of neural stem cells occurs via Nox4-generated superoxide, suggesting that an Ang II/Nox4 axis is an important regulator of neural stem cell self-renewal and as such may fine-tune normal, stress- or disease-modifying neurogenesis.

Novel Curcumin Derivative CNB-001 Mitigates Obesity-Associated Insulin Resistance

Type 2 diabetes is growing at epidemic proportions, and pharmacological interventions are being actively sought. This study examined the effect of a novel neuroprotective curcuminoid, CNB-001 [4-((1E)-2-(5-(4-hydroxy-3-methoxystyryl-)-1-phenyl-1H-pyrazoyl-3-yl)vinyl)-2-methoxy-phenol], on glucose intolerance and insulin signaling in high-fat diet (HFD)–fed mice. C57BL6 mice (5–6 weeks old) were randomly assigned to receive either a HFD (45% fat) or a low-fat diet (LFD, 10% fat) for 24 weeks, together with CNB-001 (40 mg/kg i.p. per day). Glucose tolerance test revealed that the area under the curve of postchallenge glucose concentration was elevated on HF-feeding, which was attenuated by CNB-001. CNB-001 attenuated body weight gain, serum triglycerides, and IL-6, and augmented insulin signaling [elevated phosphoprotein kinase B (p-Akt), and phosphoinsulin receptor (p-IR)β, lowered endoplasmic reticulum (ER) stress, protein–tyrosine phosphatase 1B (PTP1B)] and glucose uptake in gastrocnemius muscle of HFD-fed mice. Respiratory quotient, measured using a metabolic chamber, was elevated in HFD-fed mice, which was unaltered by CNB-001, although CNB-001 treatment resulted in higher energy expenditure. In cultured myotubes, CNB-001 reversed palmitate-induced impairment of insulin signaling and glucose uptake. Docking studies suggest a potential interaction between CNB-001 and PTP1B. Taken together, CNB-001 alleviates obesity-induced glucose intolerance and represents a potential candidate for further development as an antidiabetic agent.

Mitogen-activated protein kinase phosphatase-1 is a key regulator of hypoxia-induced vascular endothelial growth factor expression and vessel density in lung.

Although mitogen-activated protein kinase phosphatase-1 (MKP-1) is a key deactivator of MAP kinases, known effectors of lung vessel formation, whether it plays a role in the expression of proangiogenic vascular endothelial growth factor (VEGF) in hypoxic lung is unknown. We therefore hypothesized that MKP-1 is a crucial modulator of hypoxia-stimulated vessel development by regulating lung VEGF levels. Wild-type MKP-1(+/+), heterozygous MKP-1(+/-), and deficient MKP-1(-/-) mice were exposed to sea level (SL), Denver altitude (DA) (1609 m [5280 feet]), and severe high altitude (HYP) (∼5182 m [∼17,000 feet]) for 6 weeks. Hypoxia enhanced phosphorylation of p38 MAP kinase, a substrate of MKP-1, as well as α smooth muscle actin (αSMA) expression in vessels, respiratory epithelium, and interstitium of phosphatase-deficient lung. αSMA-positive vessel (<50 μm outside diameter) densities were markedly reduced, whereas vessel wall thickness was increased in hypoxic MKP-1(-/-) lung. Mouse embryonic fibroblasts (MEFs) of all three genotypes were isolated to pinpoint the mechanism involved in hypoxia-induced vascular abnormalities of MKP-1(-/-) lung. Sustained phosphorylation of p38 MAP kinase was observed in MKP-1-null MEFs in response to hypoxia exposure. Although hypoxia up-regulated VEGF levels in MKP-1(+/+) MEFs eightfold, only a 70% increase in VEGF expression was observed in MKP-1-deficient cells. Therefore, our data strongly suggest that MKP-1 might be the key regulator of vascular densities through the regulation of VEGF levels in hypoxic lung.

Spectroscopic and biological activity studies of the chromium-binding peptide EEEEGDD

While trivalent chromium has been shown at high doses to have pharmacological effects improving insulin resistance in rodent models of insulin resistance, the mechanism of action of chromium at a molecular level is not known. The chromium-binding and transport agent low-molecular-weight chromium-binding substance (LMWCr) has been proposed to be the biologically active form of chromium. LMWCr has recently been shown to be comprised of a heptapeptide of the sequence EEEEDGG. The binding of Cr3+ to this heptapeptide has been examined. Mass spectrometric and a variety of spectroscopic studies have shown that multiple chromic ions bind to the peptide in an octahedral fashion through carboxylate groups and potentially small anionic ligands such as oxide and hydroxide. A complex of Cr and the peptide when administered intravenously to mice is able to decrease area under the curve in intravenous glucose tolerance tests. It can also restore insulin-stimulated glucose uptake in myotubes rendered insulin resistant by treating them with a high-glucose media.