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A human GRPr-transfected Ace-1 canine prostate cancer model in mice.

ABSTRACT: 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.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.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.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.

SUBMITTER: Ding H

PROVIDER: S-EPMC5867903 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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A human GRPr-transfected Ace-1 canine prostate cancer model in mice.

Ding Haiming H Kothandaraman Shankaran S Gong Li L Williams Michelle M MM Dirksen Wessel P WP Rosol Thomas J TJ Tweedle Michael F MF

The Prostate 20160304 9

<h4>Background</h4>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.<h4>Methods</h4>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 fluorescen ...[more]

PMID: 26940014

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Project description:Ace-1 canine prostate cancer cells grow orthotopically in cyclosporine immunosuppressed laboratory beagles. We previously transfected (human Gastrin-Releasing Peptide Receptor, huGRPr) into Ace-1 cells and demonstrated receptor-targeted NIRF imaging with IR800-G-Abz4-t-BBN, an agonist to huGRPr. Herein, we used the new cell line to develop the first canine prostate cancer model expressing a human growth factor receptor. Dogs were immunosuppressed with cyclosporine, azathioprine, prednisolone, and methylprednisolone. Their prostate glands were implanted with Ace-1huGRPr cells. The implantation wounds were sealed with a cyanoacrylic adhesive to prevent extraprostatic tumor growth. Intraprostatic tumors grew in 4-5 week. A lobar prostatic artery was then catheterized via the carotid artery and 25-100 nmol IR800-Abz4-t-BBN was infused in 2 mL followed by euthanasia in dogs 1-2, and recovery for 24 h before euthanasia in dogs 3-6. Excised tissues were imaged optically imaged, and histopathology performed. Dog1 grew no tumors with cyclosporine alone. Using the four drug protocol, Dogs 2-6 grew abundant 1-2 mm intracapsular and 1-2 cm intraglandular tumors. Tumors grew >5 cm when the prostate cancer cells became extracapsular. Dogs 4-6 with sealed prostatic capsule implantation sites had growth of intracapsular and intraglandular tumors and LN metastases at 5 weeks. High tumor to background BPH signal in the NIRF images of sectioned prostate glands resulted from the 100 nmol dose (∼8 nmol/kg) in dogs 2-4 and 50 nmol dose in dog 5, but not from the 25 nmol dose in Dog 6. Imaging of mouse Ace-1huGRPr tumors required an intravenous dose of 500 nmol/kg body wt. A lymph node that drained the prostate gland was detectable in Dog 4. Histologic findings confirmed the imaging data. Ace-1huGRPr cells created viable, huGRPr-expressing tumors when implanted orthotopically into immune-suppressed dogs. Local delivery of an imaging agent through the prostatic artery allowed a very low imaging dose, suggesting that therapeutic agents could be used safely for treatment of early localized intraglandular prostate cancer as adjuvant therapy for active surveillance or focal ablation therapies, or for treating multifocal intraglandular disease where focal ablation therapies are not indicated or ineffective.

Project description:Background:Canine prostate cancer represents a unique model for human prostate cancer. In vitro systems offer various possibilities but Xenograft in vivo imaging allows studying complex tasks as tumor progression and drug intervention longitudinal. Herein, we established three canine prostate carcinoma cell lines stably expressing fluorescent proteins allowing deep tissue in vivo imaging. Methods:Three canine prostate carcinoma (cPC) cell lines were stably transfected with fluorescent proteins in red, far-red and near infra-red spectrum, followed by G418 selection. Fluorescent protein expression was demonstrated by microscopy, flow cytometry and a NightOWL LB 983 in vivo imaging system. Cellular and molecular characteristics of the generated cell lines were compared to the parental cell line CT1258. Cell proliferation, metabolic activity and sphere formation capacity were analyzed. Stem cell marker expression was examined by qPCR and genomic copy number variation by genomic DNA whole genome sequencing. Results:Three stably fluorescent protein transfected cPC cell lines were established and characterized. Compared to the parental cell line, no significant difference in cell proliferation and metabolic activity were detected. Genomic copy number variation analyses and stem cell marker gene expression revealed in general no significant changes. However, the generated cell line CT1258-mKate2C showed uniquely no distal CFA16 deletion and an elevated metabolic activity. The introduced fluorescencent proteins allowed highly sensitive detection in an in vivo imaging system starting at cell numbers of 0.156?×?106. Furthermore, we demonstrated a similar sphere formation capacity in the fluorescent cell lines. Interestingly, the clone selected CT1258-mKate2C, showed increased sphere formation ability. Discussion:Starting from a well characterized cPC cell line three novel fluorescent cell lines were established showing high cellular and molecular similarity to the parental cell line. The introduction of the fluorescent proteins did not alter the established cell lines significantly. The red fluorescence allows deep tissue imaging, which conventional GFP labeling is not able to realize. Conclusion:As no significant differences were detected between the established cell lines and the very well characterized parental CT1258 the new fluorescent cell lines allow deep tissue in vivo imaging for perspective in vivo evaluation of novel therapeutic regimens.

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Dataset Information

A human GRPr-transfected Ace-1 canine prostate cancer model in mice.

Publications

A human GRPr-transfected Ace-1 canine prostate cancer model in mice.

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