title: Tumor cells expressing a fusion protein of MULT1 and Fas are rejected in vivo by apoptosis and NK cell activation.
abstract: Tumor cells evade immunosurveillance by elements of the innate immune system, such as natural killer (NK) cells, by downregulating or 'shedding' certain cell-surface molecules like mouse UL16-binding protein-like transcript 1 (MULT1) that can activate NK cells through NK cell receptors such as NKG2D; they also avoid Fas-mediated apoptosis by downregulating its expression. In the present study we report the design and evaluation of the antitumor activity of a novel fusion protein, MULT1E/FasTI, consisting of the extracellular domain of MULT1 and the transmembrane and intracellular domains of Fas. The fusion construct (pMULT1E/FasTI) was transfected into the mouse pulmonary carcinoma cell line TC-1; and stable cell clones expressing the fusion protein were established. In-vitro cell culture studies demonstrated that the binding of the NKG2D/Fc, a recombinant protein of mouse NK cell receptor, to MULT1E/FasTI expressed on tumor cells was able to elicit apoptosis as assayed by Annexin V-fluorescein isothiocyanate staining and caspase-3 enzyme-linked immunosorbent assay and to activate NKG2D-expressing cells, such as NK cells. In-vivo subcutaneous tumor studies demonstrated that tumor cells expressing MULT1E/FasTI grew significantly slower than cells without the protein. Pulmonary metastasis studies showed that most of the mice completely rejected tumor cells expressing MULT1E/FasTI. This approach may generate a new therapeutic agent for tumor treatment when combined with tumor cell-specific gene delivery vehicles such as oncolytic adenovirus vectors.
authors.affiliation: Department of Biological Sciences, Clemson University, Clemson, SC, USA.
authors.forename: H S R
authors.initials: HS
authors.lastname: Kotturi
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Branham-O'Connor
authors.forename: S L
authors.initials: SL
authors.lastname: Stickel
authors.forename: X
authors.initials: X
authors.lastname: Yu
authors.forename: T E
authors.initials: TE
authors.lastname: Wagner
authors.forename: Y
authors.initials: Y
authors.lastname: Wei
mesh_terms: D000818:Animals; D017209:Apoptosis; D002277:Carcinoma / Q000276:immunology / Q000628:therapy*; D002352:Carrier Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D005260:Female; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D007694:Killer Cells, Natural / Q000276:immunology*; D008175:Lung Neoplasms / Q000276:immunology / Q000628:therapy*; D008213:Lymphocyte Activation; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000627:therapeutic use; D014162:Transfection / Q000379:methods; D019014:fas Receptor / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; C491899:Fas protein, mouse; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C468260:UL16 binding protein 1, mouse; D019014:fas Receptor