Protective effect of Phellinus linteus polysaccharide extracts against thioacetamide-induced liver fibrosis in rats: a proteomics analysis
Wang, H. ; Wu, G. ; Park, H.J. ; Jiang, P.P. ; Sit, W.H. ; Griensven, L.J.L.D. van; Wan, J.M.F. - \ 2012
Chinese Medicine 7 (2012). - ISSN 1749-8546
hepatocellular-carcinoma - oxidative stress - chain - injury - mice - gene - methyltransferase - differentiation - dehydrogenase - metastasis
Background: The hepatoprotective potential of Phellinus linteus polysaccharide (PLP) extracts has been described. However, the molecular mechanism of PLP for the inhibition of liver fibrosis is unclear. This study aims to investigate the molecular protein signatures involved in the hepatoprotective mechanisms of PLP via a proteomics approach using a thioacetamide (TAA)-induced liver fibrosis rat model. Methods: Male Sprague-Dawley rats were divided into three groups of six as follows: Normal group; TAA group, in which rats received TAA only; and PLP group, in which rats received PLP and TAA. Liver fibrosis was induced in the rats by repeated intraperitoneal injections of TAA at a dose of 200 mg/kg body weight twice a week for 4 weeks. PLP was given orally at a dose of 50 mg/kg body weight twice a day from the beginning of the TAA treatment until the end of the experiment. The development of liver cirrhosis was verified by histological examination. Liver proteomes were established by two-dimensional gel electrophoresis. Proteins with significantly altered expression levels were identified by matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry and the differentially expressed proteins were validated by immunohistochemical staining and reverse transcription polymerase chain reaction. Results: Histological staining showed a remarkable reduction in liver fibrosis in the rats with PLP treatment. A total of 13 differentially expressed proteins including actin, tubulin alpha-1C chain, preprohaptoglobin, hemopexin, galectin-5, glutathione S-transferase alpha-4 (GSTA4), branched chain keto acid dehydrogenase hterotetrameric E1 subunit alpha (BCKDHA), glutathione S-transferase mu (GSTmu); glyceraldehyde-3-phosphate dehydrogenase (GAPDH); thiosulfate sulfurtransferase (TFT); betaine-homocysteine S-methyltransferase 1 (BHMT1); quinoid dihydropteridine reductase (QDPR); ribonuclease UK114 were observed between the TAA and PLP groups. These proteins are involved in oxidative stress, heme and iron metabolism, cysteine metabolism, and branched-chain amino acid catabolism. Conclusion: The proteomics data indicate that P. linteus may be protective against TAA-induced liver fibrosis via regulation of oxidative stress pathways, heat shock pathways, and metabolic pathways for amino acids and nucleic acids.
Angiopoietin-like 4 Protein Elevates the Prosurvival Intracellular O-2(-):H2O2 Ratio and Confers Anoikis Resistance to Tumors
Zhu, P.C. ; Tan, M.J. ; Huang, R.L. ; Tan, C.K. ; Chong, H.C. ; Pal, M. ; Lam, C.R.I. ; Boukamp, P. ; Pan, J.Y. ; Tan, S.H. ; Kersten, A.H. ; Li, H.Y. ; Ding, J.L. ; Tan, N.S. - \ 2011
Cancer Cell 19 (2011)3. - ISSN 1535-6108 - p. 401 - 415.
prostate-cancer cells - beta-carotene - cardiovascular-disease - hydrogen-peroxide - redox regulation - nadph oxidase - superoxide - metastasis - survival - expression
Cancer is a leading cause of death worldwide. Tumor cells exploit various signaling pathways to promote their growth and metastasis. To our knowledge, the role of angiopoietin-like 4 protein (ANGPTL4) in cancer remains undefined. Here, we found that elevated ANGPTL4 expression is widespread in tumors, and its suppression impairs tumor growth associated with enhanced apoptosis. Tumor-derived ANGPTL4 interacts with integrins to stimulate NADPH oxidase-dependent production of O-2(-). A high ratio of O-2(-):H2O2 oxidizes/activates Src, triggering the PI3K/PKB alpha and ERK prosurvival pathways to confer anoikis resistance, thus promoting tumor growth. ANGPTL4 deficiency results in diminished O-2(-) production and a reduced O-2(-):H2O2 ratio, creating a cellular environment conducive to apoptosis. ANGPTL4 is an important redox player in cancer and a potential therapeutic target.
ANGPTL4 modulates vascular junction integrity by integrin signaling and disruption of intercellular VE-cadherin and claudin-5 clusters
Huang, R.L. ; Teo, Z.Q. ; Chong, H.C. ; Zhu, P.C. ; Tan, M.J. ; Tan, C.K. ; Lam, C.R.I. ; Sng, M.K. ; Leong, D.T.W. ; Tan, S.M. ; Kersten, A.H. ; Ding, J.L. ; Li, H.Y. ; Tan, N.S. - \ 2011
Blood : journal of the American Society of Hematology 118 (2011)14. - ISSN 0006-4971 - p. 3990 - 4002.
endothelial-cell - adherens junctions - tight junctions - 4 interacts - metastasis - cancer - permeability - catenin - lung - angiopoietin-like-4
Vascular disruption induced by interactions between tumor-secreted permeability factors and adhesive proteins on endothelial cells facilitates metastasis. The role of tumor-secreted C-terminal fibrinogen-like domain of angiopoietin-like 4 (cANGPTL4) in vascular leakiness and metastasis is controversial because of the lack of understanding of how cANGPTL4 modulates vascular integrity. Here, we show that cANGPTL4 instigated the disruption of endothelial continuity by directly inter-acting with 3 novel binding partners, integrin alpha 5 beta 1, VE-cadherin, and claudin-5, in a temporally sequential manner, thus facilitating metastasis. We showed that cANGPTL4 binds and activates integrin alpha 5 beta 1-mediated Rac1/PAK signaling to weaken cell-cell contacts. cANGPTL4 subsequently associated with and declustered VE-cadherin and claudin-5, leading to endothelial disruption. Interfering with the formation of these cANGPTL4 complexes delayed vascular disruption. In vivo vascular permeability and metastatic assays performed using ANGPTL4-knockout and wild-type mice injected with either control or ANGPTL4-knockdown tumors confirmed that cANGPTL4 induced vascular leakiness and facilitated lung metastasis in mice. Thus, our findings elucidate how cANGPTL4 induces endothelial disruption. Our findings have direct implications for targeting cANGPTL4 to treat cancer and other vascular pathologies. (Blood. 2011;118(14):3990-4002)
CCBE1 Is Essential for Mammalian Lymphatic Vascular Development and Enhances the Lymphangiogenic Effect of Vascular Endothelial Growth Factor-C In Vivo
Bos, F.L. ; Caunt, M. ; Peterson-Maduro, J. ; Planas-Paz, L. ; Schulte-Merker, S. - \ 2011
Circulation Research 109 (2011). - ISSN 0009-7330 - p. 486 - 491.
metastasis - disease - system
Rationale: Collagen- and calcium-binding EGF domains 1 (CCBE1) has been associated with Hennekam syndrome, in which patients have lymphedema, lymphangiectasias, and other cardiovascular anomalies. Insight into the molecular role of CCBE1 is completely lacking, and mouse models for the disease do not exist. Objective: CCBE1 deficient mice were generated to understand the function of CCBE1 in cardiovascular development, and CCBE1 recombinant protein was used in both in vivo and in vitro settings to gain insight into the molecular function of CCBE1. Methods and Results: Phenotypic analysis of murine Ccbe1 mutant embryos showed a complete lack of definitive lymphatic structures, even though Prox1+ lymphatic endothelial cells get specified within the cardinal vein. Mutant mice die prenatally. Proximity ligation assays indicate that vascular endothelial growth factor receptor 3 activation appears unaltered in mutants. Human CCBE1 protein binds to components of the extracellular matrix in vitro, and CCBE1 protein strongly enhances vascular endothelial growth factor-C–mediated lymphangiogenesis in a corneal micropocket assay. Conclusions: Our data identify CCBE1 as a factor critically required for budding and migration of Prox-1+ lymphatic endothelial cells from the cardinal vein. CCBE1 probably exerts these effects through binding to components of the extracellular matrix. CCBE1 has little lymphangiogenic effect on its own but dramatically enhances the lymphangiogenic effect of vascular endothelial growth factor-C in vivo. Thus, our data suggest CCBE1 to be essential but not sufficient for lymphangiogenesis.
Angiopoietin-Like 4 Interacts with Integrins ß1 and ß5 to Modulate Keratinocyte Migration
Goh, Y.Y. ; Pal, M. ; Chong, H.C. ; Zhu, P. ; Tan, M.J. ; Punugu, L. ; Lam, C.R.I. ; Yau, Y.H. ; Tan, C.K. ; Huang, R.L. ; Tan, S. ; Yang Tang, M.B. ; Ling Ding, J. ; Kersten, A.H. ; Tan, N.S. - \ 2010
American Journal of Pathology 177 (2010)6. - ISSN 0002-9440 - p. 2791 - 2803.
induced adipose factor - cell-migration - alpha-6-beta-4 integrin - in-vivo - protein - kinase - expression - repair - metastasis - inhibition
Adipose tissue secretes adipocytokines for energy homeostasis, but recent evidence indicates that some adipocytokines also have a profound local impact on wound healing. Upon skin injury, keratinocytes use various signaling molecules to promote reepithelialization for efficient wound closure. In this study, we identify a novel function of adipocytokine angiopoietin-like 4 (ANGPTL4) in keratinocytes during wound healing through the control of both integrin-mediated signaling and internalization. Using two different in vivo models based on topical immuno-neutralization of ANGPTL4 as well as ablation of the ANGPTL4 gene, we show that ANGPTL4-deficient mice exhibit delayed wound reepithelialization with impaired keratinocyte migration. Human keratinocytes in which endogenous ANGPTL4 expression was suppressed by either siRNA or a neutralizing antibody show impaired migration associated with diminished integrin-mediated signaling. Importantly, we identify integrins ß1 and ß5, but not ß3, as novel binding partners of ANGPTL4. ANGPTL4-bound integrin ß1 activated the FAK-Src-PAK1 signaling pathway, which is important for cell migration. The findings presented herein reveal an unpredicted role of ANGPTL4 during wound healing and demonstrate how ANGPTL4 stimulates intracellular signaling mechanisms to coordinate cellular behavior. Our findings provide insight into a novel cell migration control mechanism and underscore the physiological importance of the modulation of integrin activity in cancer metastasis