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A human GRPr‐transfected Ace‐1 canine prostate cancer model in mice
Author(s) -
Ding Haiming,
Kothandaraman Shankaran,
Gong Li,
Williams Michelle M.,
Dirksen Wessel P.,
Rosol Thomas J.,
Tweedle Michael F.
Publication year - 2016
Publication title -
the prostate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.295
H-Index - 123
eISSN - 1097-0045
pISSN - 0270-4137
DOI - 10.1002/pros.23172
Subject(s) - bombesin , transfection , prostate cancer , in vivo , cell culture , prostate , cancer research , cancer , microbiology and biotechnology , chemistry , receptor , endocrinology , medicine , biology , neuropeptide , genetics
BACKGROUND A versatile drug screening system was developed to simplify early targeted drug discovery in mice and then translate readily from mice to a dog prostate cancer model that more fully replicates the features of human prostate cancer. METHODS We stably transfected human cDNA of the GRPr bombesin (BBN) receptor subtype to canine Ace‐1 prostate cancer cells (Ace‐1 huGRPr ). Expression was examined by 125 I‐Tyr 4 ‐BBN competition, calcium stimulation assay, and fluorescent microscopy. A dual tumor nude mouse xenograft model was developed from Ace‐1 CMV (vector transfected Ace‐1) and Ace‐1 huGRPr cells. The model was used to explore the in vivo behavior of two new IRDye800‐labeled GRPr binding optical imaging agents: 800‐G‐Abz4‐t‐BBN, from a GRPr agonist peptide, and 800‐G‐Abz4‐STAT, from a GRPr antagonist peptide, by imaging the tumor mice and dissected organs. RESULTS Both agents bound Ace‐1 huGRPr and PC‐3, a known GRPr‐expressing human prostate cancer cell line, with 4–13 nM IC 50 against 125 I‐Tyr 4 ‐BBN, but did not bind Ace‐1 CMV cells (vector transfected). Binding was blocked by bombesin. Ca 2+ activation assays demonstrated that Ace‐1 huGPRr expressed biologically active GRPr. Both Ace‐1 cell lines grew in the flanks of 100% of the nude mice and formed tumors of ∼0.5 cm diameter in 1 week. In vivo imaging of the mice at 800 nm emission showed GRPr+: GRPr− tumor signal brighter by a factor of two at 24 h post IV administration of 10 nmol of the imaging agents. Blood retention (4–8% ID at 1 h) was greater by a factor >10 and cumulative urine accumulation (28–30% at 4 h) was less by a factor 2 compared to a radioactive analog of the t‐BBN containing agent, 177 LuAMBA, probably due to binding to blood albumin, which we confirmed in a mouse serum assay. CONCLUSIONS The dual tumor Ace‐1 CMV /Ace‐1 huGRPr model system provides a rapid test of specific to nonspecific binding of new GRPr avid agents in a model that will extend logically to the known Ace‐1 orthotopic canine prostate cancer model. Prostate 76:783–795, 2016 . © 2016 Wiley Periodicals, Inc.