title: CD40·FasL and CTLA-4·FasL fusion proteins induce apoptosis in malignant cell lines by dual signaling.
abstract: Evolution of apoptosis resistance in both lymphoma and leukemia cells is well documented, and induction of apoptosis in malignant cells is a major goal of cancer therapy. Up-regulation of anti-apoptotic signals is one of the mechanisms whereby resistance to apoptosis emerges. We have previously described the fusion proteins CD40·FasL and CTLA-4·FasL, which are formed from two functional membrane proteins and induce apoptosis of activated T cells. The present study explores the potential use of CD40·FasL and CTLA-4·FasL for the killing of malignant cells of lymphatic origin. Using malignant B and T cell lines that differ in surface expression of costimulatory molecules, we found that CTLA-4·FasL induces effective apoptosis of cells expressing CD95 and activates caspases 3, 8, and 9. Only B7-expressing B cells responded to CTLA-4·FasL with rapid abrogation of cFLIP expression. CD40·FasL effectively killed only the T cells that express high levels of CD40L in addition to CD95. In these cells, CD40·FasL significantly diminished cFLIP expression. Importantly, each of the fusion proteins is more potent than its respective components parts, alone or in combination. Thus, the proteins with their two functional ends deliver a pro-apoptotic signal and, in parallel, inhibit an anti-apoptotic signal, thus optimizing the wanted, death-inducing effect. Therefore, these proteins emerge as promising agents to be used for targeted and specific tumor cell killing.
authors.affiliation: Nephrology and Hypertension Services, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel.
authors.forename: Ariel
authors.initials: A
authors.lastname: Orbach
authors.forename: Jacob
authors.initials: J
authors.lastname: Rachmilewitz
authors.forename: Noam
authors.initials: N
authors.lastname: Shani
authors.forename: Yonatan
authors.initials: Y
authors.lastname: Isenberg
authors.forename: Miriam
authors.initials: M
authors.lastname: Parnas
authors.forename: Jui-Han
authors.initials: JH
authors.lastname: Huang
authors.forename: Mark L
authors.initials: ML
authors.lastname: Tykocinski
authors.forename: Michal
authors.initials: M
authors.lastname: Dranitzki-Elhalel
mesh_terms: D015703:Antigens, CD / Q000235:genetics / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D019013:CD40 Antigens / Q000235:genetics / Q000494:pharmacology*; D060908:CTLA-4 Antigen; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D053222:Fas Ligand Protein / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells; D058990:Molecular Targeted Therapy; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D015703:Antigens, CD; D019013:CD40 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D053222:Fas Ligand Protein; D011993:Recombinant Fusion Proteins