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19-12-2011 | Endocrinology | Article

Ghrelin analog may serve as prostate cancer diagnostic tool


Free abstract

MedWire News: Gherlin analog probes may be valuable in prostate cancer diagnosis as they can differentiate between benign and malignant prostate growths, report Canadian researchers.

John Lewis (University of Western Ontario, London) and co-investigators identified that the imaging probe fluorescein-ghrelin (1-18) has specific affinity for cancerous prostate tissue, but not for normal prostate tissue or areas of benign prostate hyperplasia.

This is a particularly beneficial property as "current radiopharmaceuticals in clinical use such as 18F-FDG (fluorodeoxyglucose) are unable to accurately distinguish between malignant and benign disease," add the researchers.

They note that the hormone ghrelin is expressed in most tissues of the body, including the prostate gland; however, the receptor at which gherlin acts, growth hormone secretagogue receptor (GHSR), is minimally expressed in normal prostate tissue.

Previous research has shown that GHSR expression is greater in cancerous than normal prostate issue.

To investigate this observation, the team recruited 13 men scheduled for radical prostatectomy. Prostate tissue biopsy samples taken from these men were used to evaluate the selectivity of a gherlin-based probe (fluoresceinghrelin [1-18]) for prostate cancer, prostate intraepithelial neoplasia (PIN), benign tissue hyperplasia, and normal prostate tissue.

As reported in the journal The Prostate, the researchers found a significantly higher uptake of the ghrelin probe by GHSR-expressing cells in cancerous prostate tissue than in all other types of prostate tissue.

Indeed, Lewis and team found that the ghrelin probe signal was almost fivefold higher in prostate cancer tissue compared with benign hyperplastic and normal prostate tissue.

In addition, the ghrelin probe signal was almost twofold higher in PIN compared with benign hyperplasia and normal tissue, but, probe signal strength did not differ significantly between benign hyperplasia and normal tissue.

These results indicate that fluoresceinghrelin (1-18)-based imaging may be a clinically effective tool for the differentiation of benign, pre-cancerous, and cancerous prostate tumors, remark the researchers.

Lewis concluded: "Imaging tests such as positron emission tomography or magnetic resonance imaging are used to diagnose a number of cancers without biopsy, but biopsy is still the best option for prostate cancer.

"This work suggests that imaging using gherlin may allow us to perform a non-invasive biopsy to diagnose prostate cancer and potentially detect metastasis earlier."

By Lauretta Ihonor

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