title: Salvicine inactivates beta 1 integrin and inhibits adhesion of MDA-MB-435 cells to fibronectin via reactive oxygen species signaling.
abstract: Integrin-mediated adhesion to the extracellular matrix plays a fundamental role in tumor metastasis. Salvicine, a novel diterpenoid quinone compound identified as a nonintercalative topoisomerase II poison, possesses a broad range of antitumor and antimetastatic activity. Here, the mechanism underlying the antimetastatic capacity of salvicine was investigated by exploring the effect of salvicine on integrin-mediated cell adhesion. Salvicine inhibited the adhesion of human breast cancer MDA-MB-435 cells to fibronectin and collagen without affecting nonspecific adhesion to poly-l-lysine. The fibronectin-dependent formation of focal adhesions and actin stress fibers was also inhibited by salvicine, leading to a rounded cell morphology. Furthermore, salvicine down-regulated beta(1) integrin ligand affinity, clustering and signaling via dephosphorylation of focal adhesion kinase and paxillin. Conversely, salvicine induced extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) phosphorylation. The effect of salvicine on beta(1) integrin function and cell adhesion was reversed by U0126 and SB203580, inhibitors of MAPK/ERK kinase 1/2 and p38 MAPK, respectively. Salvicine also induced the production of reactive oxygen species (ROS) that was reversed by ROS scavenger N-acetyl-l-cysteine. N-acetyl-l-cysteine additionally reversed the salvicine-induced activation of ERK and p38 MAPK, thereby maintaining functional beta(1) integrin activity and restoring cell adhesion and spreading. Together, this study reveals that salvicine activates ERK and p38 MAPK by triggering the generation of ROS, which in turn inhibits beta(1) integrin ligand affinity. These findings contribute to a better understanding of the antimetastatic activity of salvicine and shed new light on the complex roles of ROS and downstream signaling molecules, particularly p38 MAPK, in the regulation of integrin function and cell adhesion.
authors.affiliation: Division of Anti-Tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, PR China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhou
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Jing-Yu
authors.initials: JY
authors.lastname: Lang
authors.forename: Jin-Jian
authors.initials: JJ
authors.lastname: Lu
authors.forename: Jian
authors.initials: J
authors.lastname: Ding
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism*; D022001:Focal Adhesions / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009285:Naphthoquinones / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D022502:Stress Fibers / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D005353:Fibronectins; D019012:Integrin beta1; D009285:Naphthoquinones; D017382:Reactive Oxygen Species; C122096:salvicine; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020742:rhoA GTP-Binding Protein