Tumor cells expressing a fusion protein of MULT1 and Fas are rejected in vivo by apoptosis and NK cell activation.
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.
Kotturi
H S R
HS
Department of Biological Sciences, Clemson University, Clemson, SC, USA.
Li
J
J
Branham-O'Connor
M
M
Stickel
S L
SL
Yu
X
X
Wagner
T E
TE
Wei
Y
Y
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*
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