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Urokinase-type plasminogen activator (uPA) is a serine protease that is involved in cancer progression, especially invasion and metastasis including prostate cancer. uPA activation is mediated by transactivation of uPAR and epidermal growth factor receptor (EGF-R) in prostate cancer progression. Prostate cancer (PC-3) cells have highly invasive capacity and they express uPA and uPAR gene. PC-3 cells are treated with quercetin, which inhibits invasion and migration of PC-3 cells. Quercetin downregulates uPA, uPAR and EGF, EGF-R mRNA expressions. Quercetin inhibits cell survival factor β-catenin, NF-κB and also proliferative signalling molecules such as p-EGF-R, N-Ras, Raf-1, c.Fos c.Jun and p-c.Jun protein expressions. But quercetin increased p38 mitogen-activated protein kinase protein expression. Our results suggest that quercetin inhibit migration and invasion of prostate cancer cells. It shows the value for treatment of invasive and metastasis type of prostate cancer.

Prostate cancer incidence and mortality rates have increased over the past years. The purpose of the present study was to examine the molecular mechanism underlying the chemopreventive effects of quercetin on prostate cancer in an in vivo model. Sprague-Dawley male rats were divided into four groups, Group I: vehicle control (propylene glycol), Group II: chemically induced cancer model (MNU + T); Group III: chemically induced cancer model + quercetin (200 mg per kg b.w.); Group IV: quercetin (200 mg per kg b.w.). Serum levels of quercetin were assessed by high performance liquid chromatography (HPLC). EGFR, PI3K/Akt protein levels were significantly increased in chemically induced cancer rats, which were brought back to normalcy in both DLP & VP (dorsolateral prostate & ventral prostate) by quercetin supplementation. Also, the protein expression levels of proliferating cell nuclear antigen (PCNA), N-cadherin, vimentin, and cyclin D1 exhibited a significant increase in both DLP & VP of chemically induced cancer rats. However, simultaneous quercetin supplementation significantly decreased PCNA, N-cadherin, vimentin, and cyclin D1 protein levels compared to chemically induced cancer rats. The E-cadherin expression was decreased in chemically induced cancer animals. Simultaneous quercetin supplementation prevented it. Real time PCR was used to study the mRNA expression of snail, slug and twist. Quercetin significantly decreased snail, slug, and twist mRNA levels in chemically induced cancer rats. To conclude from the present study, quercetin was effective in preventing prostate cancer progression by inhibiting the EGFR signaling pathway and by regulating cell adhesion molecules in Sprague Dawley rats.