JY0691, a newly synthesized obovatol derivative, inhibits cell cycle progression of rat aortic smooth muscle cells through up-regulation of p21cip1

Metformin inhibits pulmonary artery smooth muscle cell proliferation by upregulating p21 via NONRATT015587.2

Pulmonary artery hypertension (PAH) is a complex and progressive disease characterized by pulmonary vascular remodeling. Our previous study confirmed that NONRATT015587.2 could promote the proliferation of PASMCs and pulmonary vascular remodeling. However, the exact mechanism by which NONRATT015587.2 promotes PASMC proliferation is unclear. Bioinformatics analysis revealed that p21 is located at the downstream target of NONRATT015587.2. NONRATT015587.2 expression and localization were analyzed by PCR and fluorescence in situ hybridization. Proliferation was detected by Cell Counting Kit-8, flow cytometry and western blotting. In the current study, a monocrotaline (MCT)-induced PAH rat model and cultured pulmonary artery smooth muscle cells (PASMCs) were used in vitro to elucidate the exact mechanism of NONRATT015587.2 in pulmonary vascular remodeling, alongside the effect following metformin (MET) treatment on vascular remodeling and smooth muscle cell proliferation. The results demonstrated that NONRATT015587.2 expression was upregulated in the MCT group and reduced in the MET + MCT group. In addition, NONRATT015587.2 could promote the proliferation of PASMCs. The expression levels of p21 were reduced in the MCT group, but increased in the MCT + MET group. Additionally, the expression of NONRATT015587.2 was upregulated in platelet-derived growth factor-BB (PDGF-BB)-induced PASMCs, whereas that of p21 was downregulated. Following MET treatment, the expression of NONRATT015587.2 was downregulated and that of p21 was upregulated, which inhibited the proliferation of PASMCs. After overexpression of NONRATT015587.2 in vitro, the proliferation effect of PASMCs was consistent with exogenous PDGF-BB treatment, and MET reversed this effect. NONRATT015587.2 silencing inhibited the proliferation of PASMCs. In addition, p21 silencing reversed the inhibitory effect of NONRATT015587.2 silencing on the proliferation of PASMCs. However, the proliferation of PASMCs was inhibited following MET treatment when NONRATT015587.2 and p21 were silenced at the same time. Thus, NONRATT015587.2 promoted the proliferation of PASMCs by targeting p21, and MET inhibited the proliferation of PASMCs by upregulating p21 mediated via NONRATT015587.2.

Potassium bisperoxo (1,10-phenanthroline) oxovanadate suppresses proliferation of hippocampal neuronal cell lines by increasing DNA methyltransferases

Bisperoxo (1,10-phenanthroline) oxovanadate (BpV) can reportedly block the cell cycle. The present study examined whether BpV alters gene expression by affecting DNA methyltransferases (DNMTs), which would impact the cell cycle. Immortalized mouse hippocampal neuronal precursor cells (HT22) were treated with 0.3 or 3 μM BpV. Proliferation, morphology, and viability of HT22 cells were detected with an IncuCyte real-time video imaging system or inverted microscope and 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium, respectively. mRNA and protein expression of DNMTs and p21 in HT22 cells was detected by real-time polymerase chain reaction and immunoblotting, respectively. In addition, DNMT activity was measured with an enzyme-linked immunosorbent assay. Effects of BpV on the cell cycle were analyzed using flow cytometry. Results demonstrated that treatment with 0.3 μM BpV did not affect cell proliferation, morphology, or viability; however, treatment with 3 μM BpV decreased cell viability, increased expression of both DNMT3B mRNA and protein, and inhibited the proliferation of HT22 cells; and 3 μM BpV also blocked the cell cycle and increased expression of the regulatory factor p21 by increasing DNMT expression in mouse hippocampal neurons.

Cinnamon and its Components Suppress Vascular Smooth Muscle Cell Proliferation by Up-Regulating Cyclin-Dependent Kinase Inhibitors

Cinnamomum cassia bark has been used in traditional herbal medicine to treat a variety of cardiovascular diseases. However, the antiproliferative effect of cinnamon extract on vascular smooth muscle cells (VSMCs) and the corresponding restenosis has not been explored. Hence, after examining the effect of cinnamon extract on VSMC proliferation, we investigated the possible involvement of signal transduction pathways associated with early signal and cell cycle analysis, including regulatory proteins. Besides, to identify the active components, we investigated the components of cinnamon extract on VSMC proliferation. Cinnamon extract inhibited platelet-derived growth factor (PDGF)-BB-induced VSMC proliferation and suppressed the PDGF-stimulated early signal transduction. In addition, cinnamon extract arrested the cell cycle and inhibited positive regulatory proteins. Correspondingly, the protein levels of p21 and p27 not only were increased in the presence of cinnamon extract, also the expression of proliferating cell nuclear antigen (PCNA) was inhibited by cinnamon extract. Besides, among the components of cinnamon extract, cinnamic acid (CA), eugenol (EG) and cinnamyl alcohol significantly inhibited the VSMC proliferation. Overall, the present study demonstrates that cinnamon extract inhibited the PDGF-BB-induced proliferation of VSMCs through a G0/G1 arrest, which down-regulated the expression of cell cycle positive regulatory proteins by up-regulating p21 and p27 expression.

Skp2-mediated degradation of p27 regulates cell cycle progression in compressed human bladder smooth muscle cells

Bladder outlet obstruction (BOO) results in smooth muscle cell hyperplasia, decreased bladder wall compliance, and lower and upper urinary tract pathology. Mechanical stimulus on detrusor tissue is critical to BOO disease progression. Our previous studies confirm that mechanical stimulus triggers human bladder smooth muscle cell (HBSMC) proliferation. To better understand the signal transduction mechanisms for this process we detected cell cycle machinery of HBSMC (Bose ® Biodynamic, Minnetonka, MN, USA). HBSMCs cultured in scaffolds were subjected to four different pressures (0 cmH2O, 100 cmH2O, 200 cmH2O, and 300 cmH2O) for 24 hours, which were controlled by a BOSE BioDynamic bioreactor. Then we used flow cytometry to examine cell cycle distribution, polymerase chain reaction, and immunoblotting to quantify Skp2, p27, and p21 expression in each group. Additionally, Skp2 was silenced in HBSMCs using small interfering RNA to validate the role of Skp2 in mediating pressure-induced cell cycle progression. Compared with the 0 cmH2O control, HBSMCs in the 200 cmH2O and 300 cmH2O groups exhibited high-level expression of Skp2 gene and low-level expression of p27 protein. However, p21, another downstream signal of Skp2, showed no significant change between groups. In addition, Skp2 silencing abolished increases in cell proliferation induced by pressure. To the best of our knowledge, this is the first report on the functional importance of Skp2 in cyclic hydrodynamic pressure stimulated HBSMC proliferation. The signal transduction mechanism for this process involves p27 as well as p21 signaling pathway.

JJK694, a synthesized obovatol derivative, inhibits platelet activation by suppressing cyclooxygenase and lipoxygenase activities

Obovatol has various biological activities, including anti-proliferative, neurotrophic, anti-fibrillogenic, anti-platelet, anti-fungal and anti-inflammatory activities. In this study, we investigated the effects of JJK694, a synthesized obovatol derivative, on rabbit platelet activation and its molecular mechanisms. JJK694 significantly inhibited washed rabbit platelet aggregation and serotonin secretion induced by collagen and arachidonic acid, but had little effect on thrombin- or U46619-induced aggregation. These results suggest that JJK694 selectively inhibits collagen- and arachidonic acid-mediated signaling. JJK694 also showed a concentration-dependent decrease in cytosolic Ca(2+) mobilization, but it had no effect on arachidonic acid liberation. On the other hand, it significantly inhibited the formation of arachidonic acid metabolites, including thromboxane A(2) (TXA(2)), prostaglandin D(2), and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), by suppression of cyclooxygenase (COX)-1 and lipoxygenase (LOX) activities. These results indicate that JJK694 hasanti-platelet activities through inhibition of arachidonic acid metabolite production by suppression of COX-1 and LOX activities.

Therapeutic applications of compounds in the Magnolia family

The bark and/or seed cones of the Magnolia tree have been used in traditional herbal medicines in Korea, China and Japan. Bioactive ingredients such as magnolol, honokiol, 4-O-methylhonokiol and obovatol have received great attention, judging by the large number of investigators who have studied their pharmacological effects for the treatment of various diseases. Recently, many investigators reported the anti-cancer, anti-stress, anti-anxiety, anti-depressant, anti-oxidant, anti-inflammatory and hepatoprotective effects as well as toxicities and pharmacokinetics data, however, the mechanisms underlying these pharmacological activities are not clear. The aim of this study was to review a variety of experimental and clinical reports and, describe the effectiveness, toxicities and pharmacokinetics, and possible mechanisms of Magnolia and/or its constituents.