Inhibition of development of abdominal aortic aneurysm by glycolysis restriction.

OBJECTIVE: The mechanisms underlying abdominal aortic aneurysm development remain unknown. We hypothesized that acceleration of glucose metabolism with the upregulation of glucose transporters is associated with abdominal aortic aneurysm development. METHODS AND RESULTS: Enhanced accumulation of the modified glucose analogue 18 fluoro-deoxyglucose by positron emission tomography imaging in the human abdominal aortic aneurysm was associated with protein expressions of glucose transporters-1 and -3, assessed by Western blot. The magnitude of glucose transporter-3 expression was correlated with zymographic matrix metalloproteinase-9 activity. Intraperitoneal administration of glycolysis inhibitor with 2-deoxyglucose significantly attenuated the dilatation of abdominal aorta induced by periaortic application of CaCl(2) in C57BL/6J male mice or reduced the aneurysmal formation in angiotensin II-infused apolipoprotein E knockout male mice. In monocytic cell line induced by phorbol 12-myristate 13-acetate or ex vivo culture obtained from human aneurysmal tissues, 2-deoxyglucose abrogated the matrix metalloproteinase-9 activity and interleukin-6 expression in these cells/tissues. Moreover, 2-deoxyglucose attenuated the survival/proliferation of monocytes and the adherence of them to vascular endothelial cells. CONCLUSIONS: This study suggests that the enhanced glycolytic activity in aortic wall contributes to the pathogenesis of aneurysm development. In addition, pharmacological intervention in glycolytic activity might be a potential therapeutic target for the disorder.

HMGA2 maintains oncogenic RAS-induced epithelial-mesenchymal transition in human pancreatic cancer cells.

Pancreatic cancer is a highly aggressive malignancy due to elevated mitotic activities and epithelial-mesenchymal transition (EMT). Oncogenic RAS and transforming growth factor-beta signaling are implicated in these malignant features. The mechanisms that underlie EMT need to be addressed since it promotes tissue invasion and metastasis. The high-mobility group A protein 2 (HMGA2) is a non-histone chromatin factor that is primarily expressed in undifferentiated tissues and tumors of mesenchymal origin. However, its role in EMT in pancreatic cancer is largely unknown. Here we report that HMGA2 is involved in EMT maintenance in human pancreatic cancer cells. Specific knockdown of HMGA2 inhibited cell proliferation, leading to an epithelial-state transition that restores cell-cell contact due to E-cadherin up-regulation. Consistently, an inverse correlation between HMGA2-positive cells and E-cadherin-positive cells was found in cancer tissues. Inhibition of the RAS/MEK pathway also induced an epithelial transition, together with HMGA2 down-regulation. Transcriptional repressors of the E-cadherin gene, such as SNAIL, decreased after HMGA2 knockdown since HMGA2 directly activated the SNAlL gene promoter. The decrease of SNAIL after RAS/MEK inhibition was suppressed by HMGA2 overexpression. Further, let-7 microRNA-mediated HMGA2 down-regulation had no effect on the prevention of the transformed phenotype in these cells. These data shed light on the importance of HMGA2 in reversibly maintaining EMT, suggesting that HMGA2 is a potential therapeutic target for the treatment of pancreatic cancer.

HMGA1 is induced by Wnt/beta-catenin pathway and maintains cell proliferation in gastric cancer.

The development of stomach cancer is closely associated with chronic inflammation, and the Wnt/beta-catenin signaling pathway is activated in most cases of this cancer. High-mobility group A (HMGA) proteins are oncogenic chromatin factors that are primarily expressed not only in undifferentiated tissues but also in various tumors. Here we report that HMGA1 is induced by the Wnt/beta-catenin pathway and maintains proliferation of gastric cancer cells. Specific knockdown of HMGA1 resulted in marked reduction of cell growth. The loss of beta-catenin or its downstream c-myc decreased HMGA1 expression, whereas Wnt3a treatment increased HMGA1 and c-myc transcripts. Furthermore, Wnt3a-induced expression of HMGA1 was inhibited by c-myc knockdown, suggesting that HMGA1 is a downstream target of the Wnt/beta-catenin pathway. Enhanced expression of HMGA1 coexisted with the nuclear accumulation of beta-catenin in about 30% of gastric cancer tissues. To visualize the expression of HMGA1 in vivo, transgenic mice expressing endogenous HMGA1 fused to enhanced green fluorescent protein were generated and then crossed with K19-Wnt1/C2mE mice, which develop gastric tumors through activation of both the Wnt and prostaglandin E2 pathways. Expression of HMGA1-enhanced green fluorescent protein was normally detected in the forestomach, along the upper border of the glandular stomach, but its expression was also up-regulated in cancerous glandular stomach. These data suggest that HMGA1 is involved in proliferation and gastric tumor formation via the Wnt/beta-catenin pathway.

Pharmacological stimulation of soluble guanylate cyclase modulates hypoxia-inducible factor-1alpha in rat heart.

Mechanical load and ischemia induce a series of adaptive physiological responses by activating the expression of O(2)-regulated genes, such as hypoxia inducible factor-1alpha (HIF-1alpha). The aim of this study was to explore the interaction between HIF-1alpha and soluble guanylate cyclase (sGC) and its second messenger cGMP in cultured cardiomyocytes exposed to hypoxia and in pressure-overloaded heart. In cultured cardiomyocytes of neonatal rats, either sGC stimulator BAY 41-2272 or cGMP analog 8-bromo-cGMP decreased the hypoxia (1% O(2)/5% CO(2))-induced HIF-1alpha expression, whereas the inhibition of protein kinase G by KT-5823 reversed the effect of BAY 41-2272 on the expression under hypoxic conditions. In pressure-overloaded heart induced by suprarenal aortic constriction (AC) in 7-wk-old male Wistar rats, the administration of BAY 41-2272 (2 mg.kg(-1).day(-1)) for 14 days significantly suppressed the protein expression of HIF-1alpha (P < 0.05), vascular endothelial growth factor (P < 0.01), and the number of capillary vessels (P < 0.01) induced by pressure overload. This study suggests that the pharmacological sGC-cGMP stimulation modulates the HIF-1alpha expression in response to hypoxia or mechanical load in the heart.

Platypus Pou5f1 reveals the first steps in the evolution of trophectoderm differentiation and pluripotency in mammals.

Uterine nourishment of embryos by the placenta is a key feature of mammals. Although a variety of placenta types exist, they are all derived from the trophectoderm (TE) cell layer of the developing embryo. Egg-laying mammals (platypus and echidnas) are distinguished by a very short intrauterine embryo development, in which a simple placenta forms from TE-like cells. The Pou5f1 gene encodes a class V POU family transcription factor Oct3/4. In mice, Oct3/4 together with the highly conserved caudal-related homeobox transcription factor Cdx2, determines TE fate in pre-implantation development. In contrast to Cdx2, Pou5f1 has only been identified in eutherian mammals and marsupials, whereas, in other vertebrates, pou2 is considered to be the Pou5f1 ortholog. Here, we show that platypus and opossum genomes contain a Pou5f1 and pou2 homolog, pou2-related, indicating that these two genes are paralogues and arose by gene duplication in early mammalian evolution. In a complementation assay, we found that platypus or human Pou5f1, but not opossum or zebrafish pou2, restores self-renewal in Pou5f1-null mouse ES cells, showing that platypus possess a fully functional Pou5f1 gene. Interestingly, we discovered that parts of one of the conserved regions (CR4) is missing from the platypus Pou5f1 promoter, suggesting that the autoregulation and reciprocal inhibition between Pou5f1 and Cdx2 evolved after the divergence of monotremes and may be linked to the development of more elaborate placental types in marsupial and eutherian mammals.

Pressure-independent effects of pharmacological stimulation of soluble guanylate cyclase on fibrosis in pressure-overloaded rat heart.

Cardiac fibrosis is a hallmark of cardiovascular remodeling associated with hypertension. The purpose of this study was to explore the effect and mechanism of soluble guanylate cyclase (sGC) stimulator BAY 41-2272, leading to intracellular cyclic guanosine monophosphate (cGMP) elevation, on the remodeling process induced by pressure overload. Seven-week-old male Wistar rats with hypertension induced by suprarenal aortic constriction (AC) were treated orally with 2 mg kg(-1) day(-1) of BAY 41-2272 for 14 days. BAY 41-2272 had no effects on blood pressure, but decreased AC-induced collagen accumulation in the left ventricle (LV), inhibiting the number of myofibroblasts and gene expressions of transforming growth factor-beta1 and type 1 collagen. In addition, the antifibrotic action of BAY 41-2272 was accompanied by reducing AC-induced angiotensin-converting enzyme (ACE) mRNA and its enzymatic activity, and angiotensin II concentration in LV. In cultured cardiac fibroblasts, BAY 41-2272 inhibited ACE synthesis and myofibroblast transformation, accompanied by elevating the intracellular cGMP concentration. These results suggest that sGC stimulator BAY 41-2272 might be effective to reduce fibrosis in hypertensive heart disease by attenuating angiotensin II generation through myofibroblast transformation.

Inhibition of DNA binding of Sox2 by the SUMO conjugation.

Sox2 is a member of the high mobility group (HMG) domain DNA-binding proteins for transcriptional control and chromatin architecture. The HMG domain of Sox2 binds the DNA to facilitate transactivation by the cooperative transcription factors such as Oct3/4. We report that mouse Sox2 is modified by SUMO at lysine 247. Substitution of the target lysine to arginine lost the sumoylation but little affected transcriptional potential or nuclear localization of Sox2. By contrast with the unmodified form, Sox2 fused to SUMO-1 did not augment transcription via the Fgf4 enhancer in the presence of Oct3/4. Further, SUMO-1-conjugated Sox2 at the lysine 247 or at the carboxyl terminus reduced the binding to the Fgf4 enhancer. These indicate that Sox2 sumoylation negatively regulates its transcriptional role through impairing the DNA binding.