Quantification and characterization of the bystander effect in prostate cancer cells following adenovirus-mediated FasL expression.
Inducing Fas-mediated apoptosis in prostate cancer (PCa) is a promising new therapeutic approach with the potential to overcome delivery issues currently problematic in cancer gene therapy. We have previously demonstrated that a Fas Ligand (FasL) expressing adenovirus (AdGFPFasL(TET)) was able to induce Fas-mediated apoptosis in a panel of PCa cell lines regardless of their Fas-sensitivity as determined by the agonistic Fas antibody CH-11. We now report that AdGFPFasL(TET)-infected cells produce apoptotic bodies and cellular debris that continues to elicit FasL-mediated bystander killing in uninfected neighboring cells. Using light microscopy, we demonstrate that AdGFPFasL(TET)-infected cells release apoptotic bodies and cellular debris into the local environment and that this material will induce bystander killing in Jurkat, PPC-1, and PC-3 target cells, but not in DU145 and K-562 cells. The bystander killing mechanism is mediated through Fas/FasL interaction because it is significantly inhibited if target cells are pretreated with the pan spectrum caspase inhibitor Z-VAD-FMK or the Fas neutralizing antibody ZB-4. Coincubation of PPC-1 target cells with apoptotic bodies and cellular debris (effector material) induce nearly complete target cell killing at a ratio of 1:1 target to effector. Collectively, these data indicate that AdGFPFasL(TET)-infected PCa cells release apoptotic and cellular debris capable of inducing bystander killing in PCa and supports the development of FasL as a gene therapy agent.
Hyer
Marc L
ML
Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC 29425, USA.
Sudarshan
Sunil
S
Schwartz
David A
DA
Hannun
Yusuf
Y
Dong
Jian-yun
JY
Norris
James S
JS
D000256:Adenoviridae / Q000235:genetics*; D017209:Apoptosis; D024201:Bystander Effect; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D053222:Fas Ligand Protein; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D019169:Jurkat Cells; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011471:Prostatic Neoplasms / Q000473:pathology / Q000628:therapy*
D061945:Caspase Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins