Time filter

Source Type

Yang T.,Sun Yat Sen University | Yang T.,University of Utah | Du Y.,Guangdong Provincial Peoples Hospital
American Journal of Hypertension

Prostaglandin E2 (PGE2) is a major prostanoid with a wide variety of biological activities. PGE2 can influence blood pressure (BP) both positively and negatively. In particular, centrally administered PGE2 induces hypertension whereas systemic administration of PGE2 produces a hypotensive effect. These physiologically opposing effects are generated by the existence of multiple EP receptors, namely EP 1-4, which are G protein-coupled receptors with distinct signaling properties. This review highlights the distinct roles of PGE 2 in BP regulation and the involvement of specific EP receptor subtypes. © 2012 American Journal of Hypertension, Ltd. Source

Jin Y.,Sun Yat Sen University | Lu Z.,Sun Yat Sen University | Ding K.,CAS Guangzhou Institute of Biomedicine and Health | Li J.,Sun Yat Sen University | And 6 more authors.
Cancer Research

NF-κB may be a potential therapeutic target for acute myelogenous leukemia (AML) because NF-κB activation is found in primitive human AML blast cells. In this report, we initially discovered that the potent antineoplastic effect of niclosamide, a Food and Drug Administration-approved antihelminthic agent, was through inhibition of the NF-κB pathway in AML cells. Niclosamide inhibited the transcription and DNA binding of NF-κB. It blocked tumor necrosis factor-induced IκBá phosphorylation, translocation of p65, and expression of NF-κB-regulated genes. Niclosamide inhibited the steps TAK1→IκB kinase (IKK) and IKK→Iκ Bá. Niclosamide also increased the levels of reactive oxygen species (ROS) inAML cells. Quenching ROS by the glutathione precursor N-acetylcysteine attenuated niclosamide-induced apoptosis. Our results together suggest that niclosamide inhibited the NF-κB pathway and increased ROS levels to induce apoptosis in AML cells. On translational study of the efficacy of niclosamide against AML, niclosamide killed progenitor/stem cells from AML patients but spared those from normal bone marrow. Niclosamide was synergistic with the frontline chemotherapeutic agents cytarabine, etoposide, and daunorubicin. It potently inhibited the growth of AML cells in vitro and in nude mice. Our results support further investigation of niclosamide in clinical trials of AML patients. ©2010 AACR. Source

Xie M.,Guangzhou University | Liu M.,Guangzhou University | He C.-S.,Guangdong Provincial Peoples Hospital

Background: Sirtuin 1 (SIRT1) acts as a key regulator of vascular endothelial homeostasis, angiogenesis, and endothelial dysfunction. However, the underlying mechanism for SIRT1-mediated lung carcinoma angiogenesis remains unknown. Herein, we report that the nicotinamide adenine dinucleotide 1 (NAD1)-dependent deacetylase SIRT1 can function as an intrinsic negative modulator of Delta-like ligand 4 (DLL4)/Notch signaling in Lewis lung carcinoma (LLC) xenograft-derived vascular endothelial cells (lung cancer-derived ECs). Principal Findings: SIRT1 negatively regulates Notch1 intracellular domain (N1IC) and Notch1 target genes HEY1 and HEY2 in response to Delta-like ligand 4 (DLL4) stimulation. Furthermore, SIRT1 deacetylated and repressed N1IC expression. Quantitative chromatin immunoprecipitation (qChIP) analysis and gene reporter assay demonstrated that SIRT1 bound to one highly conserved region, which was located at approximately -500 bp upstream of the transcriptional start site of Notch1,and repressed Notch1 transcription. Inhibition of endothelial cell growth and sprouting angiogenesis by DLL4/Notch signaling was enhanced in SIRT1-silenced lung cancer-derived EC and rescued by Notch inhibitor DAPT. In vivo, an increase in proangiogenic activity was observed in Matrigel plugs from endothelial-specific SIRT1 knock-in mice. SIRT1 also enhanced tumor neovascularization and tumor growth of LLC xenografts. Conclusions: Our results show that SIRT1 facilitates endothelial cell branching and proliferation to increase vessel density and promote lung tumor growth through down-regulation of DLL4/Notch signaling and deacetylation of N1IC. Thus, targeting SIRT1 activity or/and gene expression may represent a novel mechanism in the treatment of lung cancer. © 2012 Xie et al. Source

Chen R.,Guangdong Provincial Peoples Hospital
Nan fang yi ke da xue xue bao = Journal of Southern Medical University

To investigate the infection of Helicobacter pylori (Hp) in the liver tissue of patients with chronic liver disease and the association between Hp and chronic liver disease. Liver tissue samples were obtained by liver biopsy and surgical resection from 30 healthy subjects, 30 patients with chronic hepatitis, 30 with cirrhosis and 30 with liver cancer. All the samples were confirmed by pathological examination. The gene fragment coding for 16SrRNA were amplified by PCR with sequence analysis. The PCR product of the 16SrRNA gene was 109 bp in length. Hp 16SrRNA was detected in 18 out of 30 liver biopsy samples from patients with primary cancer (60.0%), in 14 samples from patients with liver cirrhosis (47.0%), and in none of the samples from normal subjects or patients with chronic hepatitis. Sequencing analysis of Hp 16SrRNA gene in the liver tissue showed a 98.8% homology with the gene fragment encoding Hp 16SrRNA. Hp is identified in the liver tissue of patients with chronic liver disease, suggesting the possible correlation between Hp infection and hepatocellular carcinoma. Source

Xie M.,Sun Yat Sen University | Xie M.,Guangzhou Medical College | Zhang L.,Sun Yat Sen University | He C.-S.,Guangdong Provincial Peoples Hospital | And 5 more authors.
Journal of Cellular Biochemistry

Despite an initial response to EGFR tyrosine kinase inhibitors (EGFR-TKI) in EGFR mutant lung cancer, most patients eventually become resistant and result in treatment failure. Recent studies have shown that epithelial to mesenchymal transition (EMT) is associated with drug resistance and cancer cell metastasis. Strong multiple gene signature data indicate that EMT acts as a determinant of insensitivity to EGFR-TKI. However, the exact mechanism for the acquisition of the EMT phenotype in EGFR-TKI resistant lung cancer cells remains unclear. In the present study, we showed that the expression of Notch-1 was highly upregulated in gefitinib-resistant PC9/AB2 lung cancer cells. Notch-1 receptor intracellular domain (N1IC), the activated form of the Notch-1 receptor, promoted the EMT phenotype in PC9 cells. Silencing of Notch-1 using siRNA reversed the EMT phenotype and restored sensitivity to gefitinib in PC9/AB2 cells. Moreover, Notch-1 reduction was also involved in inhibition of anoikis as well as colony-formation activity of PC9/AB2 cells. Taken together, these results provide strong molecular evidence that gefitinib-acquired resistance in lung cancer cells undergoing EMT occurs through activation of Notch-1 signaling. Thus, inhibition of Notch-1 can be a novel strategy for the reversal of the EMT phenotype thereby potentially increasing therapeutic drug sensitivity to lung cancer cells. © 2011 Wiley Periodicals, Inc. Source

Discover hidden collaborations