Efficacy of anti-death receptor 5 (DR5) antibody (TRA-8) against primary human ovarian carcinoma using a novel ex vivo tissue slice model.
OBJECTIVE
The purpose of this study was to evaluate the cytotoxicity of a death receptor 5 (DR5) targeting monoclonal antibody (TRA-8) in primary ovarian cancer specimens utilizing a tissue slice technique that allows for assessment of anti-tumor activity in a three-dimensional ex vivo model.


METHODS
Nineteen primary ovarian tumor specimens were obtained at the time of cytoreductive surgery and tumor slices were prepared with the Krumdieck tissue slicer. Tumor slices were incubated with TRA-8 for 24 h and a dose-response curve was established for each specimen using non-linear modeling, with IC50 values used as the parameter of TRA-8 sensitivity. In parallel with ATP viability assays, TRA-8 treated and untreated tumor slices were assessed by immunohistochemistry (IHC) and western blot analysis to confirm apoptosis induction.


RESULTS
Incubation with 0-1000 ng/ml TRA-8 resulted in a dose response with maximum killing observed at 1000 ng/ml compared to untreated control slices. IC50 values of 6.0 to >1000 ng/ml were calculated for individual tumor specimens. H&E, IHC, and western blot specimens demonstrated TRA-8-induced cellular death in a dose-dependent fashion via apoptosis and activation of caspases 3, 8, and 9. The apoptosis produced by varying concentrations of TRA-8 was confirmed using the TUNEL technique. Treatment with TRA-8 markedly reduced proliferation in the ovarian cancer cells as measured by expression of Ki-67/SP6.


CONCLUSIONS
This study demonstrates that targeting DR5 with TRA-8 decreases cellular proliferation, increases caspase activation, and induces apoptosis in this novel three-dimensional ex vivo model of primary ovarian cancer.
Estes
Jacob M
JM
Division of Gynecologic Oncology, The University of Alabama at Birmingham, 619 19th Street South, OHB 538, Birmingham, AL 35249, USA. jmestes21@mac.com
Oliver
Patsy G
PG
Straughn
J Michael
JM
Zhou
Tong
T
Wang
Wenquan
W
Grizzle
William E
WE
Alvarez
Ronald D
RD
Stockard
Cecil R
CR
LoBuglio
Albert F
AF
Buchsbaum
Donald J
DJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D015153:Blotting, Western; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D020128:Inhibitory Concentration 50; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000276:immunology*
D000911:Antibodies, Monoclonal; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand