gw-3965 and Prostatic-Neoplasms

Liver X receptor (LXR) isoforms, LXRα and LXRβ, have similar protein structures and ligands, but diverse tissue distribution. We used two synthetic, non-steroidal LXR agonists, T0901317 and GW3965, to investigate the effects of LXR agonist modulation on prostate specific antigen (PSA) via the expressions of androgen receptors (AR), LXRα, or LXRβ, in prostate carcinoma cells.. LXRα- or LXRβ-knockdown cells were transduced with specific shRNA lentiviral particles. LXRα and LXRβ expressions were assessed by immunoblotting and RT-qPCR assays. Cell proliferation was determined by (3) H-thymidine incorporation assays. The effects of LXR agonists and epigallocatechin gallate (EGCG) on PSA expression were determined by ELISA, immunoblotting, or transient gene expression assays.. Treatment with either T0901317 or GW3965 significantly attenuated cell proliferation of LNCaP cells. T0901317 treatment suppressed PSA expression while GW3965 treatment enhanced PSA expression. The increase of PSA promoter activity by GW3965 was dependent on the expression of AR. Either LXRα- or LXRβ-knockdown did not affect the activation of androgen on PSA gene expression. However, as compared with mock knockdown-LNCaP cells, the LXRα-knockdown but not the LXRβ-knockdown attenuated the effects of T0901317 and GW3965 on PSA expressions. The effect of GW3965 on PSA expression was blocked by the addition of EGCG.. Our results indicate that T0901317 and GW3965 have divergent effects on PSA expressions. The effects of LXR agonists on PSA expression are LXRα-dependent and AR-dependent. EGCG blocks the inducing effect of GW3965 on PSA expression.

Topics: Benzoates; Benzylamines; Catechin; Cell Line, Tumor; Cell Proliferation; Humans; Hydrocarbons, Fluorinated; Liver X Receptors; Male; Orphan Nuclear Receptors; Prostate-Specific Antigen; Prostatic Neoplasms; Receptors, Androgen; Sulfonamides

Down-regulation of suppressor of cytokine signaling 3 (SOCS3) inhibits prostate cancer (PCa) cell growth. Liver X receptors (LXRs) agonists have been recently introduced for PCa treatment. We postulated that LXR may inhibit the carcinogenesis of PCa via the SOCS3 pathway.. LNCaP cells were cultured and transfected with SOCS3 small-interfering RNA (SOCS3-siRNA) and control small-interfering RNA (control-siRNA). Then cells were treated with LXR activator (GW3965). The expressions of PCa related transcript factors, e.g. transcription 3 (STAT3), nuclear factor kappa B (NF-κB) and activation protein 1(AP1) were detected by western blot assay. In vitro cell proliferation, cell migration, cell invasion and apoptosis were analysed. Nude mice were used for in vivo tumorgenesis.. In cells treated with control-siRNA, GW3965 enhanced SOCS3 expression and significantly inhibited the phosphorylation of STAT3, NF-κB and AP1 expressions, accompanied by dramatically reduced cellular proliferation rate, immigration and invasion of cultured cells. In cells treated with SOCS3-siRNA, the inhibitory effects of LXR activator on the phosphorylation of STAT3 and expressions of NF-κB and AP1 were totally abolished. The cell proliferation rate, immigration and invasion were markedly elevated by SOCS3 gene mutation, even with GW3965 treatment. The in vivo tumorgenesis assay showed that GW3965 significantly reduced the tumor volumes in tumor-bearing nude mice receiving saline injection, but failed to limit the tumor volume in tumor-bearing nude mice receiving SOCS3 antibody injection.. Our results provide evidence in support of the notion that LXR agonist may regulate the carcinogenesis of PCa via the SOCS3 pathway.

Topics: Animals; Benzoates; Benzylamines; Blotting, Western; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Humans; Liver X Receptors; Male; Mice, Nude; Orphan Nuclear Receptors; Prostatic Neoplasms; RNA, Small Interfering; Signal Transduction; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Transfection

Prostate cancer is the most commonly diagnosed and the second leading cause of cancer death in men. The androgens-androgen receptor signaling plays an important role in normal prostate development, as well as in prostatic diseases, such as benign hyperplasia and prostate cancer. Accordingly, androgen ablation has been the most effective endocrine therapy for hormone-dependent prostate cancer. Here, we report a novel nuclear receptor-mediated mechanism of androgen deprivation. Genetic or pharmacological activation of the liver X receptor (LXR) in vivo lowered androgenic activity by inducing the hydroxysteroid sulfotransferase 2A1, an enzyme essential for the metabolic deactivation of androgens. Activation of LXR also inhibited the expression of steroid sulfatase in the prostate, which may have helped to prevent the local conversion of sulfonated androgens back to active metabolites. Interestingly, LXR also induced the expression of selected testicular androgen synthesizing enzymes. At the physiological level, activation of LXR in mice inhibited androgen-dependent prostate regeneration in castrated mice. Treatment with LXR agonists inhibited androgen-dependent proliferation of prostate cancer cells in a LXR- and sulfotransferase 2A1-dependent manner. In summary, we have revealed a novel function of LXR in androgen homeostasis, an endocrine role distinct to the previously known sterol sensor function of this receptor. LXR may represent a novel therapeutic target for androgen deprivation, and may aid in the treatment and prevention of hormone-dependent prostate cancer.

Topics: Androgens; Animals; Benzoates; Benzylamines; Cells, Cultured; DNA-Binding Proteins; Drug Resistance, Neoplasm; Gene Expression Regulation, Enzymologic; Humans; Hydroxycholesterols; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neoplasms, Hormone-Dependent; Orphan Nuclear Receptors; Prostate; Prostatic Neoplasms; Receptors, Cytoplasmic and Nuclear; Regeneration; Sulfotransferases; Testosterone