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Updated: Mar 24, 2026
A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
A human GRPr-transfected Ace-1 canine prostate cancer model in mice
Haiming Ding1, Shankaran Kothandaraman1, Li Gong1
1Department of Radiology, The Wright Center for Innovation in Biomolecular Imaging, The Wexner Medical Center, The Ohio State University, Columbus, Ohio.
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 IC50 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.
Insights
A novel dual tumor mouse model allows for rapid screening of gastrin-releasing peptide receptor (GRPr) binding agents. This system translates to canine models for improved prostate cancer drug discovery.
Area of Science:
- Oncology
- Pharmacology
- Biotechnology
Background:
- Development of a versatile drug screening system for early-stage targeted drug discovery.
- Translational potential from mouse models to a dog prostate cancer model that better replicates human disease.
Purpose of the Study:
- To establish and validate a dual tumor mouse xenograft model for evaluating gastrin-releasing peptide receptor (GRPr) targeted agents.
- To assess the in vivo performance of novel IRDye800-labeled GRPr binding optical imaging agents.
Main Methods:
- Stable transfection of canine prostate cancer cells (Ace-1) with human GRPr cDNA.
- Development of a dual tumor model using Ace-1(huGRPr) and control Ace-1(CMV) cells in nude mice.
- In vivo imaging and biodistribution studies of IRDye800-labeled GRPr agonist and antagonist agents.
Main Results:
- Both imaging agents demonstrated specific binding to GRPr-expressing cells (Ace-1(huGRPr)) with high affinity (4-13 nM IC50).
- In vivo imaging revealed a two-fold brighter signal in GRPr-positive tumors compared to GRPr-negative tumors 24 hours post-injection.
- The optical agents exhibited favorable pharmacokinetic profiles with lower blood retention and urine accumulation compared to a radioactive analog.
Conclusions:
- The dual tumor Ace-1(CMV)/Ace-1(huGRPr) model system enables rapid assessment of GRPr-avid agent specificity.
- This model is readily extendable to the orthotopic canine prostate cancer model for further preclinical evaluation.
- The developed system facilitates efficient drug discovery and development for prostate cancer.
