carnosol and Prostatic-Neoplasms

To investigate the effect of carnosol on the Hedgehog (HH) signaling pathway in human hormone-dependent prostate cancer cell line LNCaP and hormone-independent prostate cancer cell line DU145. The expression levels of glioma-associated oncogene homolog 1 (Gli1) and Sonic hedgehog (Shh) in human prostate cancer tissues were detected by immunohistochemistry. After treated with carnosol (0.25-16 μmol/L), the cell survival of LNCaP and DU145 cells were detected by MTT assay. The expression levels of Gli1 and Shh mRNA and protein in the two cells were detected by qRT-PCR and western blot, respectively. The apoptosis was determined by the caspase-3 activity assay. Results showed that Shh and Gli1 were upregulated in cancer tissues. The inhibitory effect of carnosol on cell survival was enhanced with concentration, suggesting both LNCaP and DU145 cells were sensitive to carnosol. The inhibitory effects of carnosol on Gli1 and Shh mRNAs in the hormone-dependent LNCaP prostate cancer cell was stronger than that in the hormone-independent DU145 prostate cancer cells. Carnosol downregulated the expression of Gli1 in nucleus, and Shh in cells. Greater carnosol concentration resulted in lower levels of Gli1 and Shh. Carnosol increased caspase-3 activity in a dose-dependent manner, suggesting that carnosol promotes cell apoptosis. Thus, carnosol can inhibit the proliferation and induce the apoptosis of prostate cancer cells in vitro, and its mechanism might be associated with the inhibiting of HH signaling pathway. Although the inhibitory effect of carnosol on hormone-dependent LNCaP prostate cancer cells is stronger than hormone-independent DU145 prostate cancer cells, carnosol might be a potential drug for hormone-independent prostate cancer.

Topics: Abietanes; Aged; Aged, 80 and over; Antineoplastic Agents, Phytogenic; Case-Control Studies; Caspase 3; Cell Line, Tumor; Cell Survival; Gene Expression Regulation, Neoplastic; Hedgehog Proteins; Humans; Lamiaceae; Male; Middle Aged; Neoplasm Grading; Prostatic Hyperplasia; Prostatic Neoplasms; Signal Transduction; Transurethral Resection of Prostate; Zinc Finger Protein GLI1

Emerging data are suggesting that estrogens, in addition to androgens, may also be contributing to the development of prostate cancer (PCa). In view of this notion, agents that target estrogens, in addition to androgens, may be a novel approach for PCa chemoprevention and treatment. Thus, the identification and development of nontoxic dietary agents capable of disrupting androgen receptor (AR) in addition to estrogen receptor (ER) could be extremely useful in the management of PCa. Through molecular modeling, we found that carnosol, a dietary diterpene, fits within the ligand-binding domain of both AR and ER-alpha. Using a time-resolved fluorescence resonance energy transfer assay, we found that carnosol interacts with both AR and ER-alpha and additional experiments confirmed that it functions as a receptor antagonist with no agonist effects. LNCaP, 22Rv1, and MCF7 cells treated with carnosol (20-40 mumol/L) showed decreased protein expression of AR and ER-alpha. Oral administration of carnosol at 30 mg/kg 5 days weekly for 28 days to 22Rv1 PCa xenografted mice suppressed tumor growth by 36% (P = 0.028) and was associated with a decrease in serum prostate-specific antigen by 26% (P = 0.0042). These properties make carnosol unique to any known antiandrogen or antiestrogen investigated thus far for the simultaneous disruption of AR and ER-alpha. We suggest that carnosol may be developed or chemically modified through more rigorous structure-activity relationship studies for a new class of investigational agents-a dual AR/ER modulator.

Topics: Abietanes; Androgen Antagonists; Animals; Antineoplastic Agents, Phytogenic; Carcinoma; Cell Line, Tumor; Diet; Diterpenes; Estrogen Antagonists; Estrogen Receptor alpha; Humans; Male; Mice; Prostatic Neoplasms; Receptors, Androgen; Xenograft Model Antitumor Assays

This study examines the anti-cancer effect of carnosol in human prostate cancer PC3 cells and its role in modulating multiple signaling pathways associated with carcinogenesis.. PC3 cells were treated with carnosol and were evaluated using a flow cytometry, a protein array and Western blot analysis to identify signaling pathways targeted by carnosol.. Using an MTT assay we found that carnosol (10-70 microM) decreases cell viability in a time and dose-dependent manner. Further analysis using flow cytometry as well as biochemical analysis identified G2-phase cell cycle arrest. To establish a more precise mechanism, we performed a protein array that evaluated 638 proteins involved in cell signaling pathways. The protein array identified 5'-AMP-activated protein kinase (AMPK), a serine/threonine protein kinase involved in the regulation of cellular energy balance as a potential target. Further downstream effects consistent with cancer inhibition included the modulation of the mTOR/HSP70S6k/4E-BP1 pathway. Additionally, we found that carnosol targeted the PI3K/Akt pathway in a dose dependent manner.. These results suggest that carnosol targets multiple signaling pathways that include the AMPK pathway. The ability of carnosol to inhibit prostate cancer in vitro suggests carnosol may be a novel agent for the management of PCa.

Topics: Abietanes; AMP-Activated Protein Kinases; Anticarcinogenic Agents; Apoptosis Regulatory Proteins; Blotting, Western; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Flow Cytometry; G2 Phase; Humans; Male; Multienzyme Complexes; Phosphatidylinositol 3-Kinases; Prostatic Neoplasms; Protein Array Analysis; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; Time Factors