title: Enhanced antitumorigenic effects in glioblastoma on double targeting of pleiotrophin and its receptor ALK.
abstract: In adults, glioblastomas are the most lethal and most frequent malignant brain tumors, and the poor prognosis despite aggressive treatment indicates the need to establish novel targets for molecular intervention. The secreted growth factor pleiotrophin (PTN, HB-GAM, HBNF, OSF-1) shows mitogenic, chemotactic, and transforming activity. Whereas PTN expression is tightly regulated during embryogenesis and is very limited in normal adult tissues, a marked PTN up-regulation is seen in tumors including glioblastomas. Likewise, the PTN receptor anaplastic lymphoma kinase (ALK) has been shown previously to be upregulated and functionally relevant in glioblastoma. In this study, we explore the antitumorigenic effects of the simultaneous ribozyme-mediated knockdown of both receptor and ligand. Various glioblastoma cell lines are analyzed for PTN and ALK expression. Beyond the individual efficacies of several specific ribozymes against PTN or ALK, respectively, antiproliferative and proapoptotic effects of a single gene targeting approach are strongly enhanced on double knockdown of both genes in vitro. More importantly, this results in the abolishment of tumor growth in an in vivo subcutaneous tumor xenograft model. Finally, the analysis of various downstream signaling pathways by antibody arrays reveals a distinct pattern of changes in the activation of signal transduction molecules on PTN/ALK double knockdown. Beyond the already known ones, it identifies additional pathways relevant for PTN/ALK signaling. We conclude that double targeting of PTN and ALK leads to enhanced antitumorigenic effects over single knockdown approaches, which offers novel therapeutic options owing to increased efficacy also after prolonged knockdown.
authors.affiliation: Department of Pharmacology and Toxicology, Philipps-University School of Medicine, Marburg, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Grzelinski
authors.forename: Florian
authors.initials: F
authors.lastname: Steinberg
authors.forename: Tobias
authors.initials: T
authors.lastname: Martens
authors.forename: Frank
authors.initials: F
authors.lastname: Czubayko
authors.forename: Katrin
authors.initials: K
authors.lastname: Lamszus
authors.forename: Achim
authors.initials: A
authors.lastname: Aigner
mesh_terms: D000077548:Anaplastic Lymphoma Kinase; D000818:Animals; D016588:Anticarcinogenic Agents / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016207:Cytokines / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D055785:Gene Knockdown Techniques; D015316:Genetic Therapy; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000628:therapy*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D000078792:Midkine; D011505:Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D016337:RNA, Catalytic / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5 / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D016588:Anticarcinogenic Agents; D002352:Carrier Proteins; D016207:Cytokines; D016337:RNA, Catalytic; D012333:RNA, Messenger; C066845:pleiotrophin; D000078792:Midkine; C000626173:ALK protein, human; C000626174:Alk protein, mouse; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5