Neuronal nitric oxide synthase modulation of intracellular Ca2+ handling overrides fatty acid potentiation of cardiac inotropy in hypertensive rats.

Cardiac neuronal nitric oxide synthase (nNOS) is an important molecule that regulates intracellular Ca2+ homeostasis and contractility of healthy and diseased hearts. Here, we examined the effects of nNOS on fatty acid (FA) regulation of left ventricular (LV) myocyte contraction in sham and angiotensin II (Ang II)-induced hypertensive (HTN) rats. Our results showed that palmitic acid (PA, 100 µM) increased the amplitudes of sarcomere shortening and intracellular ATP in sham but not in HTN despite oxygen consumption rate (OCR) was increased by PA in both groups. Carnitine palmitoyltransferase-1 inhibitor, etomoxir (ETO), reduced OCR and ATP with PA in sham and HTN but prevented PA potentiation of sarcomere shortening only in sham. PA increased nNOS-derived NO only in HTN. Inhibition of nNOS with S-methyl-L-thiocitrulline (SMTC) prevented PA-induced OCR and restored PA potentiation of myocyte contraction in HTN. Mechanistically, PA increased intracellular Ca2+ transient ([Ca2+]i) without changing Ca2+ influx via L-type Ca2+ channel (I-LTCC) and reduced myofilament Ca2+ sensitivity in sham. nNOS inhibition increased [Ca2+]i, I-LTCC and reduced myofilament Ca2+ sensitivity prior to PA supplementation; as such, normalized PA increment of [Ca2+]i. In HTN, PA reduced I-LTCC without affecting [Ca2+]i or myofilament Ca2+ sensitivity. However, PA increased I-LTCC, [Ca2+]i and reduced myofilament Ca2+ sensitivity following nNOS inhibition. Myocardial FA oxidation (18F-fluoro-6-thia-heptadecanoic acid, 18F-FTHA) was comparable between groups, but nNOS inhibition increased it only in HTN. Collectively, PA increases myocyte contraction through stimulating [Ca2+]i and mitochondrial activity in healthy hearts. PA-dependent cardiac inotropy was limited by nNOS in HTN, predominantly due to its modulatory effect on [Ca2+]i handling.

Red ginseng and 20(S)-Rg3 control testosterone-induced prostate hyperplasia by deregulating androgen receptor signaling.

Since prostate growth is governed by the androgen signaling pathway, blockade of the pathway is regarded as an appropriate strategy for the treatment of benign prostatic hyperplasia (BPH). Panax ginseng is known to have various pharmacological activities. Of several products of its root, red ginseng, having many bioactive ginsenosides, is most popularly used in Korea, and recently has been reported to control the proliferation of cancer cells. We here tested the effect of a water extract of Korean red ginseng (WKRG) on testosterone-induced prostate hyperplasia. WKRG (daily intraperitoneal injection) prevented prostate overgrowth and epithelial thickening induced by testosterone in rats, and suppressed a rat prostate kallikrein-S3. In human prostate cells, WKRG inhibited testosterone-induced cell proliferation, arrested cell cycle by inducing p21 and p27, and induced apoptosis. Testosterone-induced expression of human kallikrein-3 mRNA and activation of androgen receptor (AR) were effectively inhibited by WKRG. Of the major ginsenosides included in WKRG, 20(S)-Rg3 was identified to repress AR activity and to attenuate prostate cell growth during testosterone stimulation. Moreover, 20(S)-Rg3 downregulated AR by facilitating the degradation of AR protein. WKRG and 20(S)-Rg3 were found to have new pharmacological activities against testosterone-induced prostate overgrowth. Given that red ginseng has been used safely in Asia for 1000 years, red ginseng and 20(S)-Rg3 could be potential therapeutic regimens for treating BPH.

Red ginseng deregulates hypoxia-induced genes by dissociating the HIF-1 dimer.

Water extract of Korean red ginseng (KRGW) contains numerous bioactive ginsenosides and is very popular as a multi-purpose medicine for health improvement. KRGW has been in the limelight because of its clinical benefit in cancer control. A growing body of evidence suggests that hypoxia-inducible factor-1 (HIF-1) plays critical roles in tumor promotion under hypoxia and that it is a compelling target for cancer therapy. In this paper we investigated the effect of KRGW on HIF-1-mediated adaptation to hypoxia. In both Hep3B cancer and HEK293 immortalized normal cell lines, KRGW attenuated the expression of hypoxia-induced genes without apparent cytotoxicity. Mechanistically, KRGW did not affect the synthesis, degradation, and translocation of HIF-1 in hypoxia. Interestingly, KRGW was found to repress the transcriptional activity of HIF-1 by interfering with the dimerization between HIF-1α and aryl hydrocarbon receptor nuclear translocator. To identify the HIF-inhibiting ingredient(s), we examined the effects of major ginsenosides on HIF-1 activity, but all ginsenosides tested failed to inactivate HIF-1. Based on these results, we propose that HIF-1 inhibition underlies the anticancer effect of ginseng. It is also proposed that KRGW could be an anticancer drug targeting hypoxic tumors.

Vitamin C supplementation prevents testosterone-induced hyperplasia of rat prostate by down-regulating HIF-1alpha.

Benign prostatic hyperplasia (BPH) is a disease that impairs the well-being of many aged men. To alleviate BPH symptoms or to find a cure for this disease, key molecules should be identified that control prostate cell proliferation. Recently, HIF-1alpha has attracted attention in this context, because it is highly expressed in hyperplasic prostates and prevents prostate cell death. Thus, given that vitamin C inhibits HIF-1alpha expression in several malignant tumors, we examined its therapeutic potential in BPH. HIF-1alpha was noticeably induced by testosterone in prostate cells, and this HIF-1alpha induction was abolished by vitamin C. Vascular endothelial growth factor (VEGF) promoter activity reporter assays and semi-quantitative RT-PCR revealed that vitamin C inhibited HIF-1-dependent VEGF expression. Furthermore, HIF-1alpha suppression by vitamin C was rescued by knocking down HIF-prolyl hydroxylase-2, suggesting that vitamin C destabilizes HIF-1alpha via prolyl hydroxylation. Moreover, vitamin C treatment abolished cell proliferation induced by testosterone treatment to the control level. These results suggest that vitamin C inhibits testosterone-induced HIF-1alpha expression and by so doing effectively prevents prostate hyperplasia. In male rats, testosterone treatment for 4 weeks induced prostate hyperplasia. Furthermore, HIF-1alpha and VEGF levels were significantly elevated in hyperplasic prostates. In vitamin C-treated rats, however, most prostate hyperplasia parameters and prostrate HIF-1alpha/VEGF levels were markedly reduced. Accordingly, our findings indicate that vitamin C could be further developed clinically for use as an anti-BPH agent.

Green tea polyphenol (-)-epigallocatechin gallate reduces neuronal cell damage and up-regulation of MMP-9 activity in hippocampal CA1 and CA2 areas following transient global cerebral ischemia.

Previous studies have demonstrated that (-)-epigallocatechin gallate (EGCG), a green tea polyphenol, protects against ischemia and reperfusion-induced injury in many organ systems. Here, we test the hypothesis that part of EGCG's neuroprotective effects may involve a modulation of matrix metalloproteinases (MMPs) after cerebral ischemia. C57BL/6 mice were subjected to 20 min of transient global cerebral ischemia. EGCG (50 mg/kg) or vehicle (saline) was administered i.p. immediately after ischemia. Brains were examined 3 days after ischemia. The effects of EGCG on MMP (gelatinase) activity and neuronal damage in the hippocampus were assessed. Gelatin gel zymography showed induction of active forms of MMP-9 protein after transient global cerebral ischemia. In situ zymography showed that ischemic gelatinase activity occurred primarily in pyramidal neuronal areas after brain ischemia. Mice treated with EGCG showed significantly reduced gelatinase levels. Neuronal damage was evident in CA1 and CA2 pyramidal sectors, corresponding to TUNEL-positive signals. In EGCG-treated mice, delayed neuronal damage was significantly reduced compared with vehicle-treated mice. These results demonstrate that the green tea polyphenol EGCG suppresses MMP-9 activation and reduces the development of delayed neuronal death after transient global cerebral ischemia in mouse brain.

Curcumin inhibits hypoxia-inducible factor-1 by degrading aryl hydrocarbon receptor nuclear translocator: a mechanism of tumor growth inhibition.

Hypoxia-inducible factor-1 (HIF-1), a transcription factor composed of HIF-1alpha and aryl hydrocarbon receptor nuclear translocator (ARNT), plays a key role in cell survival and angiogenesis in hypoxic tumors, and many efforts have been made to develop anticancer agents that target HIF-1alpha. However, although ARNT is also required for HIF-1 activity, ARNT has been disregarded as a therapeutic target. Curcumin is a commonly used spice and coloring agent with a variety of beneficial biological effects, which include tumor inhibition. In the present study, we tested the possibility that curcumin inhibits tumor growth by targeting HIF-1. The effects of curcumin on HIF-1 activity and expression were examined in cancer cell lines and in xenografted tumors. We found that curcumin inhibits HIF-1 activity and that this in turn down-regulates genes targeted by HIF-1. Moreover, of the two HIF-1 subunits, only ARNT was found to be destabilized by curcumin in several cancer cell types, and furthermore, ARNT expression rescued HIF-1 repression by curcumin. We also found that curcumin stimulated the proteasomal degradation of ARNT via oxidation and ubiquitination processes. In mice bearing Hep3B hepatoma, curcumin retarded tumor growth and suppressed ARNT, erythropoietin, and vascular endothelial growth factor in tumors. These results suggest that the anticancer activity of curcumin is attributable to HIF-1 inactivation by ARNT degradation.