Induce Prostate Cancer Research Articles

Abstract 5251: Chemoprevention of cadmium induced prostate carcinogenesis

Abstract Cadmium is known carcinogen that causes damages to multiple organs. Cadmium acts as an agonist and activates androgen receptor (AR) in prostate epithelial cells which in turn promotes the carcinogenesis of prostate. Studies have indicated that occupational exposure of cadmium is a risk factor for prostate cancer and hence there is an immediate need to prevent cadmium induced prostate cancer in occupational workers. Various reports have shown that inhibition of AR signaling by AR inhibitors suppressed cadmium induced prostate carcinogenesis. So, the present study focuses to identify dietary agent which can effectively prevent cadmium induced prostate cancer and to dissect the mechanism of action on malignant transformed cells. We have disclosed one such compound, 6-(3, 9-dihydroxy-2-prenylcoumestan (Psoralidin) (Pso) a non-toxic, orally bioavailable compound, which effectively targets only prostate cancer cells and innocuous to healthy cells. Our results have shown cadmium transformed prostate epithelial cells (CTPE) exhibits high proliferative and high colony forming ability in soft agar assays. However, treatment of CTPE cells with Pso resulted in growth inhibition, without causing toxicity to normal prostate epithelial cells (RWPE-1). Finally, in vivo experiments showed that oral administration of Pso (20 mg/kg/BW) effectively suppresses the growth in CTPE xenografts, at physiologically achievable doses without any toxicity. The pathological findings suggest that CTPE tumors exhibits epithelial and mesenchymal transition (EMT) phenotype and infiltrating margins into the surrounding muscle and adipose tissue. However, Psoralidin treated tumors showed a decrease in tumor size with a significant central necrosis (up to 60% of the tumor size). More specifically, margins of Psoralidin treated tumors are less infiltrative and becoming more well circumscribed. We have also noticed that the mesenchymal component is not present and the only viable tumor is the epithelial one after Pso treatment. Altogether, our results confirm that consumption of natural compounds such as Psoralidin may play an important role in the chemoprevention for cadmium induced prostate carcinogenesis. Citation Format: Suman Suman, Trinath P. Das, Houda Alatassi, Murali K. Ankem, Chendil Damodaran. Chemoprevention of cadmium induced prostate carcinogenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5251.

Loss of PKCδ Induces Prostate Cancer Resistance to Paclitaxel through Activation of Wnt/β-Catenin Pathway and Mcl-1 Accumulation.

Prostate cancer is the leading cause of cancer-related death among men in developed countries. Although castration therapy is initially effective, prostate cancers progress to hormone-refractory disease and in this case taxane-based chemotherapy is widely used. Castration-resistant prostate cancer cells often develop resistance to chemotherapy agents and the search for new therapeutic strategies is necessary. In this article, we demonstrate that PKCδ silencing favors mitotic arrest after paclitaxel treatment in PC3 and LNCaP cells; however, this is associated with resistance to paclitaxel-induced apoptosis. In prostate cancer cells, PKCδ seems to exert a proapoptotic role, acting as a negative regulator of the canonical Wnt/β-catenin pathway. PKCδ silencing induces activation of Wnt/β-catenin pathway and the expression of its target genes, including Aurora kinase A, which is involved in activation of Akt and both factors play a key role in GSK3β inactivation and consequently in the stabilization of β-catenin and antiapoptotic protein Mcl-1. We also show that combined treatments with paclitaxel and Wnt/β-catenin or Akt inhibitors improve the apoptotic response to paclitaxel, even in the absence of PKCδ. Finally, we observe that high Gleason score prostate tumors lose PKCδ expression and this correlates with higher activation of β-catenin, inactivation of GSK3β, and higher levels of Aurora kinase A and Mcl-1 proteins. These findings suggest that targeting Wnt/β-catenin or Akt pathways may increase the efficacy of taxane chemotherapy in advanced human prostate cancers that have lost PKCδ expression. Mol Cancer Ther; 15(7); 1713-25. ©2016 AACR.

Doxorubicin-Functionalized Silica Nanoparticles Incorporated into a Thermoreversible Hydrogel and Intraperitoneally Administered Result in High Prostate Antitumor Activity and Reduced Cardiotoxicity of Doxorubicin.

Described here is an anticancer material based on colloidal mesoporous silica nanoparticles (MSNs) functionalized with doxorubicin (DOX), and incorporated into Pluronic F127 hydrogels for prolonged release, with a potential therapeutic application for prostate cancer treatment. The MSNs have spherical morphology, size of about 60 nm, surface area of 970 cm2 g-1 and average pore width of 2.0 nm. A high colloidal stability for the MSNs in the physiological medium used for in vivo administration (NaCl 0.9% w/v) could be attained in the presence of PF127 (from 5 to 18 wt %), where depletion repulsion forces prevent MSN agglomeration. By conjugating DOX, MSN and PF127 (18 wt %) in NaCl 0.9%, the hybrid system has a gelation temperature of 21 °C, which allowed its in vivo administration in the liquid form and further in situ gelation, generating a drug depot system inside the animals after peritoneal injection. The systems were tested in rats with chemically induced prostate cancer and, after this treatment, histopathological analyses confirmed (i) a reduction in the frequency of aggressive tumors; (ii) that the antitumor effect was dependent on MSN concentration; and most importantly (iii) the reduction of DOX intrinsic cardiotoxicity, indicating that the MSNs play a cardioprotective effect.

A phase 1/2 study combining ipilimumab with abiraterone acetate plus prednisone in chemotherapy- and immunotherapy-naïve patients with progressive metastatic castration resistant prostate cancer (mCRPC).

e16507Background: We hypothesized that combining abiraterone acetate (AA), an androgen biosynthesis inhibitor shown to induce prostate cancer apoptosis for patients (pts) with mCRPC, with Ipilimuma...

Jungermannenone A and B induce ROS- and cell cycle-dependent apoptosis in prostate cancer cells in vitro.

Jungermannenone A and B (JA, JB) are new ent-kaurane diterpenoids isolated from Chinese liverwort Jungermannia fauriana, which show anti-proliferation activities in cancer cells. In this study we investigated the mechanisms underlying the anticancer action of JA and JB in PC3 human prostate cancer cells in vitro. A panel of 9 human cancer cell lines was tested. Cell proliferation was assessed with a real-time cell analyzer and MTT assay. Cell apoptosis, cell cycle distribution and ROS levels were measured using cytometry. Mitochondrial damage was examined by transmission electron microscopy. DNA damage was detected with comet assay. Apoptotic, DNA damage- and cell cycle-related proteins were analyzed using Western blotting. The expression of DNA repair genes was measured with qRT-PCR. Both JA and JB exerted potent anti-proliferative action against the 9 cancer cell lines, and PC3 cells were more sensitive with IC50 values of 1.34±0.09 and 4.93±0.20 μmol/L, respectively. JA (1.5 μmol/L) and JB (5 μmol/L) induced PC3 cell apoptosis, which was attenuated by the caspase inhibitor Z-VAD. Furthermore, both JA and JB caused mitochondrial damage and ROS accumulation in PC3 cells, whereas vitamin C blocked the ROS accumulation and attenuated the cytotoxicity of JA and JB. Moreover, both JA and JB induced DNA damage, accompanied by downregulated DNA repair proteins Ku70/Ku80 and RDA51. JA induced marked cell cycle arrest at the G0/G1 phase, which was related to c-Myc suppression, whereas JB enforced the cell cycle blockade in the G2/M phase, which associated with activation of the JNK signaling. Both JA and JB induce prostate cancer apoptosis via ROS accumulation and induction of cell cycle arrest.

Abstract B20: Key intermediate progenitor in luminal prostate epithelial differentiation dictates susceptibility to Myc overexpression and Pten loss in prostate cancer cell of origin

Abstract Overexpression of Myc and loss of Pten are very common oncogenic events in prostate cancer. However, why these specific oncogenic events, as opposed to others, are involved in prostate cancer develop remains unclear. While the impact of Myc and Pten on cell proliferation is well-characterized, their role in differentiation and the resulting impact on tumorigenesis is poorly understood. We recently developed an in vitro differentiation model in which basal prostate epithelial cells (PrECs) can be differentiated into secretory luminal cells. Our model offers several advantages, in that it is human-specific and readily manipulated genetically and biochemically; providing a rare opportunity to dissect the specific genetic and biochemical events associated with human PrEC differentiation and determining how it is impacted by specific oncogenic events. Using this model, we tested the hypothesis that overexpression of Myc and loss of Pten induce prostate cancer because their dysregulation impairs differentiation of an intermediate progenitor cell population that marks the tumor cell of origin. Transient induction of both Pten and Myc are required for normal PrEC differentiation. Constitutive Myc overexpression initially accelerates differentiation, but the differentiated cells ultimately die via a p53-independent mechanism. Overexpression of Myc in combination with loss of Pten (Myc+shPten), is required for tumorigenesis because it rescues cell survival and blocks terminal differentiation. We identified the chromatin binding protein, ING4, as a Myc target required for PrEC terminal differentiation. ING4 is lost in over 60% of human prostate tumors and in the Myc+shPten cells, ING4 expression is blocked. Loss of ING4 in Myc overexpressing cells is sufficient to replace loss of Pten; ING4 loss, like Pten loss, is required for tumorigenesis to block terminal differentiation and keep cells alive. We further identified Miz1, a component of the Myc repressor complex, as a direct target of ING4 required for terminal PrEC differentiation. Myc/Miz1 is required to suppress integrin α6 and β1 expression during terminal PrEC differentiation; in Myc+shPten cells, Miz1 fails to be induced and integrin α6β1 is aberrantly co-expressed with AR in an intermediate progenitor and tumorigenic cell population. Conclusions: Prostate cancer oncogenesis requires dysregulation of Myc and Pten, because they are required for the normal PrEC terminal differentiation pathway. Pten loss is required to remove the ING4/Miz1-mediated terminal differentiation program initiated by Myc overexpression, to maintain the intermediate progenitor cells in a partially differentiated, yet proliferative state, and to evade cell death. Citation Format: Penny Berger, McLane Watson, Mary Winn, Cindy K. Miranti. Key intermediate progenitor in luminal prostate epithelial differentiation dictates susceptibility to Myc overexpression and Pten loss in prostate cancer cell of origin. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr B20.

MiR‑19a‑3p targets PMEPA1 and induces prostate cancer cell proliferation, migration and invasion.

Prostate cancer (PCa) is one of the most common malignant tumors in men. Studies have observed that microRNA (miR)‑19a‑3p expression levels are downregulated in several types of cancer, and yet the biological function and its underlying mechanisms in the pathogenesis of PCa remain unclear. In the current study, the expression pattern of miR‑19a‑3p in PCa tissues and cell lines was detected by reverse transcription‑quantitative polymerase chain reaction. The proliferative, migratory and invasive capacity of PCa cells were determined using EdU and Transwell assays following transfection with miR‑19a‑3p mimics. Additionally, the current study investigated the biological impact and regulation of prostate transmembrane protein androgen induced1 (PMEPA1) in PCa cells by transfection with PMEPA1 small interfering (si)RNA. It was observed that miR‑19a‑3p was upregulated in PCa tissue samples and cell lines invitro. Functional analysis also confirmed that miR‑19a‑3p overexpression promoted the proliferation, migration and invasion of PCa cells. Furthermore, PMEPA1 was identified as a direct target of miR‑19a‑3p, and siRNA knockdown of PMEPA1 resulted in increased proliferation, migration and invasion of PCa cells, which partially accounts for the effect of miR‑19a‑3p in tumor metastasis. In conclusion, the findings of the present study suggest that the upregulation of miR‑19a‑3p expression levels contributes to tumor progression and that one of its underlying mechanisms involves inhibition of PMEPA1 expression.

Increase of human prostate cancer cell (DU145) apoptosis by telmisartan through PPAR-delta pathway

The effect of telmisartan on prostate cancer DU145 cell survival and the underlying mechanism of apoptosis involving peroxisome proliferator-activated receptor (PPAR) pathway were investigated. Cultured DU145 cells were treated pharmacologically with telmisartan and GSK0660 (a PPAR-delta antagonist); or by RNA interference with siRNA of PPAR-delta. The treatment effects on cell survival were evaluated with cell viability assay, life and dead cell staining and flow cytometry. Western blot analysis for PPAR-delta protein expression was also performed. The results showed that telmisartan (0–80µm) dose-dependently reduced DU145 cell survival. Flow cytometry demonstrated cancer cell cycle arrest with increase of sub-G1 phase. GSK0660 partially but significantly restored the telmisartan-treated cell viability. Similarly, siRNA of PPAR-delta significantly reversed the telmisartan-induced apoptosis. Western blot showed that telmisartan significantly increased DU145 cell PPAR-delta protein expression. Co-incubation with siRNA of PPAR-delta inhibited the telmisartan effect of PPAR-delta up-regulation. In conclusion, telmisartan induces prostate cancer DU145 cells apoptosis through the up-regulation of PPAR-delta protein expression. Pharmacological inhibition or genetic silencing of PPAR-delta activity can both reverse the telmisartan-induced apoptotic effect. Thus the PPAR-delta pathway might be a potential target for the treatment of prostate cancer.

The pepper's natural ingredient capsaicin induces autophagy blockage in prostate cancer cells.

Capsaicin, the pungent ingredient of red hot chili peepers, has been shown to have anti-cancer activities in several cancer cells, including prostate cancer. Several molecular mechanisms have been proposed on its chemopreventive action, including ceramide accumulation, endoplasmic reticulum stress induction and NFκB inhibition. However, the precise mechanisms by which capsaicin exerts its anti-proliferative effect in prostate cancer cells remain questionable. Herein, we have tested the involvement of autophagy on the capsaicin mechanism of action on prostate cancer LNCaP and PC-3 cells.The results showed that capsaicin induced prostate cancer cell death in a time- and concentration-dependent manner, increased the levels of microtubule-associated protein light chain 3-II (LC3-II, a marker of autophagy) and the accumulation of the cargo protein p62 suggesting an autophagy blockage. Moreover, confocal microscopy revealed that capsaicin treatment increased lysosomes which co-localized with LC3 positive vesicles in a similar extent to that produced by the lysosomal protease inhibitors E64 and pepstatin pointing to an autophagolysosomes breakdown inhibition. Furthermore, we found that capsaicin triggered ROS generation in cells, while the levels of ROS decreased with N-acetyl-cysteine (NAC), a ROS scavenger. Co-treatment of cells with NAC and capsaicin abrogated the effects of capsaicin on autophagy and cell death. Normal prostate PNT2 and RWPE-1 cells were more resistant to capsaicin-induced cytotoxicity and did not accumulate p62 protein.Taken together, these results suggest that ROS-mediated capsaicin-induced autophagy blockage contributes to antiproliferation in prostate cancer cells, which provides new insights into the anticancer molecular mechanism of capsaicin.

Serum androgens and prostate cancer risk: results from the placebo arm of the Prostate Cancer Prevention Trial.

Compelling and long-standing data suggest that androgens play an important role in the development of both normal prostate epithelium and prostate cancer. Although testosterone administration can induce prostate cancer (PCA) in laboratory animals, serum-based epidemiologic studies examining androgens in humans have not consistently supported a role for androgens in prostate carcinogenesis. We examined whether pre-diagnostic serum androgens were associated with PCA risk in the placebo arm of the Prostate Cancer Prevention Trial. In this nested case-control study, cases (n = 1,032) were primarily local-stage, biopsy-detected cancers, and controls (n = 1,025) were biopsy-confirmed to be PCA-free. Pre-diagnostic serum androgens (total testosterone, 3α-androstanediol glucuronide, free testosterone), estrogen-to-testosterone ratio, and sex hormone-binding globulin (SHBG) concentrations were measured in pooled (baseline and year 3) blood samples. We found no significant associations between serum androgens, estrogen-to-testosterone ratios, or SHBG and risk of total, low (Gleason <7) or high-grade (Gleason 7-10) PCA. Much remains to be learned about the role of androgens in prostate carcinogenesis. Further research is needed to evaluate the role of androgens, timing of exposure, genetic modulators of androgen metabolism, or environmental exposures that may affect androgen influence on prostate carcinogenesis.

Curcumin inhibits cancer-associated fibroblast-driven prostate cancer invasion through MAOA/mTOR/HIF-1α signaling.

Cancer-associated fibroblasts (CAFs) are key determinants in the malignant progression of cancer, supporting tumorigenesis and metastasis. CAFs also mediate epithelial to mesenchymal transition (EMT) in tumor cells and their achievement of stem cell traits. Curcumin has recently been found to possess anticancer activities via its effect on a variety of biological pathways involved in cancer progression. In this study, we found that CAFs could induce prostate cancer cell EMT and invasion through a monoamine oxidase A (MAOA)/mammalian target of rapamycin (mTOR)/hypoxia-inducible factor-1α (HIF-1α) signaling pathway, which exploits reactive oxygen species (ROS) to drive a migratory and aggressive phenotype of prostate carcinoma cells. Moreover, CAFs was able to increase CXC chemokine receptor 4 (CXCR4) and interleukin-6 (IL-6) receptor expression in prostate cancer cells. However, curcumin abrogated CAF-induced invasion and EMT, and inhibited ROS production and CXCR4 and IL-6 receptor expression in prostate cancer cells through inhibiting MAOA/mTOR/HIF-1α signaling, thereby supporting the therapeutic effect of curcumin in prostate cancer.

Abstract 388: EGR1 is a mediator of TWEAK-Fn14 pathway induced prostate cancer bone metastasis

Abstract Patients with advanced or castration-resistant prostate cancer have a high probability of developing bone metastasis. However, the molecular mechanisms driving bone metastasis in prostate cancer remain poorly understood. We have previously demonstrated that Fn14 expression is increased significantly in metastatic lesions from prostate cancer patients. Fn14 is a member of the TNF receptor family, and our in vivo study using DU145/RasB1 cells indicated that the TWEAK-Fn14 pathway promotes prostate cancer bone metastasis via the canonical NFκB pathway. However, the downstream targets of the TWEAK-Fn14 pathway have yet to be characterized in prostate cancer cells. To elucidate the precise mechanism underlying Fn14-promoted metastasis, we analyzed the gene expression profile of highly metastatic DU145/RasB1 and low metastatic DU145/RasB1 Fn14depleted (Fn14KD) cells. Fn14 depletion significantly altered expression of 147 genes, including ECM components, cell adhesives, and cytoskeletal regulators. In addition, DU145/RasB1 and DU145/RasB1 Fn14KD cells responded differently to TWEAK treatment. We found increased expression of early growth response 1, (EGR1), in the TWEAK-treated DU145/RasB1 cells relative to DU145/RasB1 Fn14KD cells. To determine if EGR1 plays a role in prostate cancer metastasis, we depleted EGR1 expression with two shRNAs in highly metastatic DU145/RasB1 cells. Our results show that both EGR1 shRNAs significantly inhibited bone metastasis in vivo. We also found that EGR1 expression was decreased when the NFκB pathways were inhibited by an IκB super repressor in DU145/RasB1 cells. Interestingly, both Fn14 depletion and EGR1 depletion increased TFPI2 expression and inhibited adhesion to fibrin. Fibrin has been shown to facilitate metastatic spread by assisting platelet adhesion to circulating tumor cells. These results suggest one scenario whereby activation of Fn14 signaling may promote prostate cancer bone metastasis through enhancing tumor-platelet interaction via an EGR1-dependent mechanism. Citation Format: Amir H. Ameri, JuanJuan Ivy Yin, Keith Jansen, Simeng Wang, Jessica Snyder, Paul Hynes, Kathleen Kelly. EGR1 is a mediator of TWEAK-Fn14 pathway induced prostate cancer bone metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 388. doi:10.1158/1538-7445.AM2015-388

Tumor-induced pressure in the bone microenvironment causes osteocytes to promote the growth of prostate cancer bone metastases.

Cross-talk between tumor cells and their microenvironment is critical for malignant progression. Cross-talk mediators, including soluble factors and direct cell contact, have been identified, but roles for the interaction of physical forces between tumor cells and the bone microenvironment have not been described. Here, we report preclinical evidence that tumor-generated pressure acts to modify the bone microenvironment to promote the growth of prostate cancer bone metastases. Tumors growing in mouse tibiae increased intraosseous pressure. Application of pressure to osteocytes, the main mechanotransducing cells in bone, induced prostate cancer growth and invasion. Mechanistic investigations revealed that this process was mediated in part by upregulation of CCL5 and matrix metalloproteinases in osteocytes. Our results defined the critical contribution of physical forces to tumor cell growth in the tumor microenvironment, and they identified osteocytes as a critical mediator in the bone metastatic niche.

Increased susceptibility of estrogen-induced bladder outlet obstruction in a novel mouse model

Disorders of the prostate and lower urinary tract are common in elderly men. We investigated the role of metallothionein-1 (MT1) in prostate carcinogenesis by generating a prostate-specific, MT1-expressing mouse. Unexpectedly, genomic analyses revealed that a 12.1-kb genomic region harboring several conserved noncoding elements was unintentionally deleted, upstream of the transgene integration site in the mouse, which we named it 12.1ΔMT1. Male 12.1ΔMT1 mice chronically treated with testosterone (T) plus 17β-estradiol (E2) to induce prostate cancer exhibited no evidence of precancerous or cancerous lesions. Instead, most of them exhibited a bladder outlet obstruction (BOO) phenotype not observed in treated wild-type (WT) mice. Thus, we hypothesized that 12.1ΔMT1 is a novel model for studying the hormonal requirement for BOO induction. Adult male 12.1ΔMT1 and WT mice were treated with T, E2, bisphenol A (BPA), T+E2, or T+BPA for up to 6 months. Histologic and immunohistochemical analysis of the prostate, bladder, and urethra were performed. No significant prostate pathologies were observed in WT or 12.1ΔMT1 mice treated with any of the hormone regimens. As expected, prostatic regression occurred in all E2-treated animals (WT and 12.1ΔMT1). Of great interest, despite a small prostate, 100% of E2-treated 12.1ΔMT1 mice, but only 40% of E2-treated WT mice, developed severe BOO (P<0.01). In contrast, T+E2 treatment was less effective than E2 treatment in inducing severe BOO in 12.1ΔMT1 mice (68%, P<0.05) and was completely ineffective in WT animals. Similarly, T, BPA, and T+BPA treatments did not induce BOO in either WT or 12.1ΔMT1 mice. The BOO pathology includes a thinner detrusor wall, narrowing of bladder neck and urethral lumen, and basal cell hyperplasia in the bladder body and urethra. These findings indicate that 12.1ΔMT1 mice exhibit enhanced susceptibility to E2-induced BOO that is independent of prostate enlargement but that is attenuated by the conjoint treatment with T.

In vivo nanotoxicology of hybrid systems based on copolymer/silica/anticancer drug

One of the major problems in cancer therapies is the high occurrence of side effects intrinsic of anticancer drugs. Doxorrubicin is a conventional anticancer molecule used to treat a wide range of cancer, such as breast, ovarian and prostate. However, its use is associated with a number of side effects like multidrug resistance and cardiotoxicity. The association with nanomaterials has been considered in the past decade to overcome the high toxicity of these drugs. In this context, mesoporous silica nanoparticles are great candidates to be used as carriers once they are very biocompatible. Taking into account the combination of nanoparticles and doxorrubicin, we treated rats with chemically induced prostate cancer with systems based on mesoporous silica nanoparticles and a thermoreversible block copolymer (Pluronic F-127) containing doxorrubicin. Preliminary results show a possible improvement in tumor conditions proportional to the concentration of the nanoparticles, opening a perspective to use mesoporous silica nanoparticles as carrier for doxorrubicin in prostate cancer treatment.

Role of Runx2 phosphorylation in prostate cancer and association with metastatic disease.

The osteogenic transcription factor, Runx2, is abnormally expressed in prostate cancer (PCa) and associated with metastatic disease. During bone development, Runx2 is activated by signals known to be hyperactive in PCa including the RAS/MAP kinase pathway, which phosphorylates Runx2 on multiple serine residues including S301 and S319 (equivalent to S294 and S312 in human Runx2). This study examines the role of these phosphorylation sites in PCa. Runx2 was preferentially expressed in more invasive prostate cancer cell lines (PC3 > C4-2B > LNCaP). Furthermore, analysis using a P-S319-Runx2-specific antibody revealed that the ratio of P-S319-Runx2/total Runx2 as well as P-ERK/total ERK was highest in PC3 followed by C4-2B and LNCaP cells. These results were confirmed by immunofluorescence confocal microscopy, which showed a higher percentage of PC3 cells staining positive for P-S319-Runx2 relative to C4-2B and LNCaP cells. Phosphorylated Runx2 had an exclusively nuclear localization. When expressed in prostate cell lines, wild type Runx2 increased metastasis-associated gene expression, in vitro migratory and invasive activity as well as in vivo growth of tumor cell xenografts. In contrast, S301A/S319A phosphorylation site mutations greatly attenuated these Runx2 responses. Analysis of tissue microarrays from 129 patients revealed strong nuclear staining with the P-S319-Runx2 antibody in primary prostate cancers and metastases. P-S319-Runx2 staining was positively correlated with Gleason score and occurrence of lymph node metastases while little or no Runx2 phosphorylation was seen in normal prostate, benign prostate hyperplasia or prostatitis indicating that Runx2 S319 phosphorylation is closely associated with prostate cancer induction and progression towards an aggressive phenotype. These studies establish the importance of Runx2 phosphorylation in prostate tumor growth and highlight its value as a potential diagnostic marker and therapeutic target.

The natural compound Guttiferone F sensitizes prostate cancer to starvation induced apoptosis via calcium and JNK elevation.

BackgroundIn a cytotoxicity screen in serum-free medium, Guttiferone F showed strong growth inhibitory effect against prostate cancer cells.MethodsProstate cancer cells LNCaP and PC3 were treated with Guttiferone F in serum depleted medium. Sub-G1 phase distributions were estimated with flow cytometry. Mitochondrial disruption was observed under confocal microscope using Mitotracker Red staining. Gene and protein expression changes were detected by real-time PCR and Western blotting. Ca2+ elevation was examined by Fluo-4 staining under fluorescence microscope. PC3 xenografts in mice were examined by immunohistochemical analysis.ResultsGuttiferone F had strong growth inhibitory effect against prostate cancer cell lines under serum starvation. It induced a significant increase in sub-G1 fraction and DNA fragmentation. In serum-free medium, Guttiferone F triggered mitochondria dependent apoptosis by regulating Bcl-2 family proteins. In addition, Guttiferone F attenuated the androgen receptor expression and phosphorylation of ERK1/2, while activating the phosphorylation of JNK and Ca2+ flux. Combination of caloric restriction with Guttiferone F in vivo could increase the antitumor effect without causing toxicity.ConclusionsGuttiferone F induced prostate cancer cell apoptosis under serum starvation via Ca2+ elevation and JNK activation. Combined with caloric restriction, Guttiferone F exerted significant growth inhibition of PC3 cells xenograft in vivo. Guttiferone F is therefore a potential anti-cancer compound.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1292-z) contains supplementary material, which is available to authorized users.

Prolifertive effect of 17beta‐trenbolone on human prostate cancer cell line

Trenbolone acetate (TBA) is synthetic anabolic steroid which have used in speed muscle development in cattle. Some of TBA are converted into 17beta-trenbolone (17TB, 17b-hydroxy-estra-4,9,11-trien-3-one), which exerts androgenic activity by binding with androgen receptor like testosterone and dihydrotestosterone (DHT). It has been reported that cross-talk between androgen and cell cycle regulator modulates prostate cancer cell progression. Since 17TB exhibits androgenic activity like DHT, it is important for knowing role of 17TB on prostate cancer cell progression. In this study, we found that 17TB induced prostate cancer cell proliferation with concentration dependent manner (EC50=0.03nM). Furthermore, cell growth by 17TB was completely inhibited in presence of 17TB and 10μM bicalutamide, which acts as an androgen receptor antagonist. To investigate the molecular mechanism of 17TB on prostate cancer cells, western blot analysis was performed. Indeed, 17TB increased cell cycle regulatory proteins cyclin A, cyclin B, cyclin D and it similar with DHT treatment. These data suggest that 17TB promotes 22Rv1 androgen-dependent prostate cancer cell proliferation via regulation of cell cycle.

Protease nexin 1: a novel inducer of prostate tumor cell apoptosis

Protease nexin 1 (PN1), a member of serine protease inhibitors (SERPINs) family, is known for its ability to bind and inhibit a wide range of proteases. Recently, we have found that PN1 is able to induce prostate cancer cell undergoing apoptosis through a distinct mechanism of engaging uPA-uPAR complexes and the regulation of two independent downstream signaling cascades, leading to the repression of X-linked inhibitor of apoptosis protein (XIAP). In this process, PN1 expression reduces the expression of NF-κB signalling component p65 and thereby lessens xiap transcription. Alternately, PN1 activity can prevent the stability of XIAP by reducing XIAP phosphorylation at serine 87 via a blockade of AKT signaling. A combination of exogenous PN1 and TRAIL leads to a substantial growth lag in prostate cancer xenografts, indicating the potential of PN1 as a promising target for improving prostate cancer therapy. Furthermore, human prostate tissue arrays show inverse levels of PN1 and XIAP in tumor and normal prostate. Hence, the PN1-uPA regulatory axis may serve as an inducer of tumor cell apoptosis by modulating survival pathways, and therefore delay the tumor growth of prostate cancer.

MP37-12 INSULIN-LIKE GROWTH FACTOR-I INDUCES CLU EXPRESSION THROUGH TWIST1 TO PROMOTE PROSTATE CANCER GROWTH

Clusterin (CLU) is cytoprotective molecular chaperone that is highly expressed in castrate-resistant pros- tate cancer (CRPC). CRPC is also characterized by increased insulin-like growth factor (IGF)-I responsive- ness which induces prostate cancer survival and CLU expression. However, how IGF-I induces CLU expression and whether CLU is required for IGF-mediated growth signaling remain unknown. Here we show that IGF-I induced CLU via STAT3-Twist1 signaling pathway. In response to IGF-I, STAT3 was phos- phorylated, translocated to the nucleus and bound to the Twist1 promoter to activate Twist1 transcrip- tion. In turn, Twist1 bound to E-boxes on the CLU promoter and activated CLU transcription. Inversely, we demonstrated that knocking down Twist1 abrogated IGF-I induced CLU expression, indicating that Twist1 mediated IGF-I-induced CLU expression. When PTEN knockout mice were crossed with lit/lit mice, the resultant IGF-I deficiency suppressed Twist1 as well as CLU gene expression in mouse prostate glands. Moreover, both Twist1 and CLU knockdown suppressed prostate cancer growth accelerated by IGF-I, sug- gesting the relevance of this signaling not only in an in vitro, but also in an in vivo. Collectively, this study indicates that IGF-I induces CLU expression through sequential activation of STAT3 and Twist1, and sug- gests that this signaling cascade plays a critical role in prostate cancer pathogenesis.