Human Prostate Carcinogenesis Research Articles

Oncogenic transformation of human benign prostate hyperplasia with chronic cadmium exposure

Experimentally, it has been proved that cadmium served as an effective carcinogen and able to induce tumors in rodents in a dose-specific manner. However, systemic evaluation of cadmium exposure for the transformation of prostatic hyperplasia into prostate cancer (PCa) is still unclear. In the present study, an attempt has been made to establish cadmium-induced human prostate carcinogenesis using an in vitro model of BPH cells. Wide range of cadmium concentrations, i.e., 1 nM, 10 nM, 100 nM and 1μM, were chronically exposed to the human BPH cells for transformation into PCa and monitored using cell and molecular biology approaches. After eight weeks of exposure, the cells showed subtle morphological changes and shifts of cell cycle in the G2M phase. Significant increase in expression of prostatic genes AR, PSA, ER-β, and 5αR with increased nuclear localization of AR and pluripotency markers Cmyc, Klf4 indicated the carcinogenic effect of Cd. Further, the BPH cells exposed to Cd showed a substantial increase in the secretion of MMP-2 and MMP-9, influencing migratory potential of the cells along with decreased expression of the p63 protein which further strengthen the progression towards carcinogenesis and aggressive tumor studies. Data from the present study state that Cd exhibited marked invasiveness in BPH cells. These observations established a connecting link of BPH towards PCa pathogenesis. Further, the study will also help in investigating the intricate pathways involved in cancer progression.

Dietary Tomato Varieties Similarly Inhibit Prostate Carcinogenesis in the TRAMP Model in Association with Distinct Transcriptomic and Metabolomic Profiles

Abstract Objectives Lycopene intake is associated with reduced risk of prostate cancer, especially lethal disease. Tangerine tomatoes contain highly bioavailable lycopene isomers, compared to red tomatoes, but impact of isomers on cancer preventive bioactivity are unknown. Our goals are: (1) to determine if feeding tomato containing diets with differing lycopene isomers inhibit transgenic adenocarcinoma of the mouse prostate (TRAMP) carcinogenesis, and (2) to determine key early metabolic and transcriptional pathways through which tomatoes act to prevent carcinogenesis. Methods We examine prostate carcinogenesis in the TRAMP model, comparing two tomatoes with distinct lycopene isomer profiles: all-trans-lycopene-rich red tomatoes and cis-lycopene-isomer-rich tangerine tomatoes. Weanling TRAMP and wild type (WT) mice were fed AIN-93 G control, 10% tangerine tomato + AIN-93 G (w/w), or 10% red tomato + AIN-93 G (w/w) diet until 10 or 18 wks. At 10 wks., prostate RNA-seq and plasma metabolomics were performed on TRAMP and WT samples. At 18 wks., plasma carotenoid analysis and histopathology was performed on TRAMP mice. Results At 18 wks., plasma lycopene concentrations were 2.84-fold greater in tangerine tomato-fed mice than red tomato-fed mice (p < 0.0001), yet both red and tangerine tomato diets similarly prevent carcinoma incidence compared to the control diet by 43% and 36% respectively (p < 0.001, both vs. control). Our investigation of early carcinogenesis (10 wks.) shows that both tomato diets similarly impact the plasma metabolome, and we define prostate transcriptomic profiles mediated by TRAMP genotype, such as inflammation- and immune-regulated pathways, that are inhibited by dietary tomato. We identify an inflammatory gene panel (Olr1, Il1a, Cscl9, and Ccl22) which is inhibited by tomato diets. In a human prostate cancer database, higher expression of this gene panel is associated with a more aggressive phenotype. Conclusions Together, our results implicate red and tangerine tomatoes as potentially beneficial for the inhibition of early prostate carcinogenesis through the modulation of transcriptional programs centered on inflammation and the immune response. Our findings support efforts to test novel tomato products for the inhibition of human prostate carcinogenesis. Funding Sources AICR, NIH P30, USDA NNF.

Immunoexpression of estrogen receptor-β and progesterone receptor in prostate adenocarcinoma, does it inhibit neoplastic proliferation and invasion?

The roles of estrogen and progesterone in human prostate carcinogenesis have been only recently recognized. This study was conducted to evaluate the expressions of esterone receptor-beta (ER-β), progesterone receptor (PR), and Ki-67 in benign and malignant lesions of the prostate. The study was conducted at a tertiary care hospital. It was an analytical cross-sectional study. We selected a total of 39 cases including 26 cases of benign prostatic hyperplasia and 13 cases of adenocarcinoma prostate. The proportion of cases showing expression for ER-β, PR, and Ki-67 was noted for both groups. A difference in immunoexpression between benign and malignant cases was evaluated. Association between receptor expression and Gleason grade was evaluated for malignant cases. To compare the difference in expressions of ER-β, PR, and Ki-67 Mann-Whitney U test was used. Association between ER-β, PR, and Ki-67 expression and Gleason grade was analyzed using the Chi-square test. ER-β expression was seen in all benign and malignant cases, whereas the majority of the malignant cases (61.54%) were negative for progesterone expression. Epithelial expressions of ER-β and PR were significantly higher in benign as compared with malignant lesions. Malignant cases showed a significantly higher expression of Ki-67. However, we did not find any association between the expressions of these markers with Gleason grade. The expressions of ER-β and PR were significantly higher in the epithelium in benign cases as compared with malignant cases. Ki-67 expression was significantly higher in the malignant group as compared with the benign group.

A Novel Tomato-Soy Juice Induces a Dose-Response Increase in Urinary and Plasma Phytochemical Biomarkers in Men with Prostate Cancer

Tomato and soy intake is associated with reduced prostate cancer risk or severity in epidemiologic and experimental studies. On the basis of the principle that multiple bioactives in tomato and soy may act on diverse anticancer pathways, we developed and characterized a tomato-soy juice for clinical trials. In this phase 2 dose-escalating study, we examined plasma, prostate, and urine biomarkers of carotenoid and isoflavone exposure. Men scheduled for prostatectomy were recruited to consume 0, 1, or 2 cans of tomato-soy juice/d before surgery (mean±SD duration: 24±4.6 d). The juice provided 20.6 mg lycopene and 66 mg isoflavone aglycone equivalents/177-mL can. Plasma carotenoids and urinary isoflavone metabolites were quantified by HPLC-photometric diode array and prostate carotenoids and isoflavones by HPLC-tandem mass spectrometry. We documented significant dose-response increases (P<0.05) in plasma concentrations of tomato carotenoids. Plasma concentrations were 1.86-, 1.69-, 1.73-, and 1.69-fold higher for lycopene, β-carotene, phytoene, and phytofluene, respectively, for the 1-can/d group and 2.34-, 3.43-, 2.54-, and 2.29-fold higher, respectively, for the 2-cans/d group compared with 0 cans/d. Urinary isoflavones daidzein, genistein, and glycitein increased in a dose-dependent manner. Prostate carotenoid and isoflavone concentrations were not dose-dependent in this short intervention; yet, correlations between plasma carotenoid and urinary isoflavones with respective prostate concentrations were documented (R2=0.78 for lycopene, P<0.001; R2=0.59 for dihydrodaidzein, P<0.001). Secondary clustering analyses showed urinary isoflavone metabolite phenotypes. To our knowledge, this is the first demonstration of the phytoene and phytofluene in prostate tissue after a dietary intervention. Secondary analysis showed that the 2-cans/d group experienced a nonsignificant decrease in prostate-specific antigen slope compared with 0 cans/d (P=0.078). These findings provide the foundation for evaluating a well-characterized tomato-soy juice in human clinical trials to define the impact on human prostate carcinogenesis. This trial is registered at clinicaltrials.gov as NCT01009736.

Abstract 1328: Cadmium-induced endoplasmic reticulum stress causes defective autophagy in human prostate carcinogenesis

Abstract Introduction: Exposure to cadmium (Cd) is associated with a spectrum of human pathogenesis including the prostate cancer (CaP). A clear dose-response relation between Cd-exposure and CaP have been reported in men exposed to Cd. However, the molecular mechanism underlying the malignant cell transformation following Cd exposure is yet to be determined. One of the possible mechanisms is that Cd causes endoplasmic reticulum (ER) stress, which further induces defective autophagy that plays a cytoprotective role in response to the misfolded and unfolded proteins that are formed during cellular transformation. Hence, the goal of this study is to investigate the underlying mechanism of how Cd causes malignant cell transformation (from normal to cancer cells) and on the development of tumorigenesis by the Cd-transformed cells. Methods: Normal prostate epithelial cells (RWPE-1) and Cd (10µM)-transforming prostate epithelial cells and cadmium-transformed prostate epithelial cells (CTPE) were utilized. Overexpression and/or silence ER-sensors, EGFR, and p62 were performed in above mention cell lines and subjected to cell viability, apoptosis, autophagy functional studies and Western blot analyses. For statistical analysis, data were analyzed using Student's ‘t' test with a p-value less than 0.05 considered significant. Results: Our preliminary results suggest that during cellular transformation, Cd exposure induced ER-stress, which triggered the phosphorylation of stress transducers including protein kinase R-like ER Kinase (PERK) and e1F2-α (eukaryotic translation initiation factor 2A-alpha). Phosphorylation resulted in the activation of ATF4 (Activating Transcription Factor 4) and autophagy induction thus enhancing protection of Cd-damaged cells. Further, inhibition of stress inducers (ATF4) or p62 by siRNA blocked the Cd-induced defective autophagy resulted in growth inhibition in transforming cells. Interestingly, in Cd-transformed cells, blocking EGFR activation by siRNA or pharmacological inhibitors significantly inhibited the growth, but not in the transforming cells suggesting that EGFR activation plays a critical role only after cellular transformation. Further, xenograft tumor tissues generated by Cd-transformed cells expressed high levels of ATF-4, EGFR, p62 and LC3B in correlation with in vitro findings. Moreover, increased expression of the proteins (ATF-4, EGFR, p62, and LC3B) in human CaP specimens correlates with Gleason sum in comparison with benign prostatic hyperplasia and “normal” adjacent tissues. Conclusions: The results suggest that ER stress responsible for the defective autophagy in Cd-induced transformation. This study highlights the better understanding of the complex interrelationship among prostate cancer phenotypes and the molecular, cellular, biochemical, and pathological changes associated with Cd and prostate cancer. Citation Format: Venkatesh Kolluru, Ashish Tyagi, Balaji Chandrasekaran, Murali K. Ankem, Chendil Damodaran. Cadmium-induced endoplasmic reticulum stress causes defective autophagy in human prostate carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1328.

Abstract 5061: TET inhibits prostate cancer tumor growth, progression and metastasis in TRAMP mice

Abstract Introduction: Prostate cancer (PCa) is the 2nd most common malignancy in USA. Novel agents for treatment of advanced PCa are warranted. Transgenic adenocarcinoma of the mouse prostate (TRAMP) is an autochthonous mouse model exhibits both histological and morphological features that mimic human prostate carcinogenesis. Herein, for the first time, we evaluated the in vivo effects of TET, a derivative of Tetrandrine in TRAMP model. Methods: Beginning 12 weeks of age, male TRAMP mice were administrated with TET (30 mgm/kg body weight, orally, alternative days) in PBS or PBS alone (Control) till 30 weeks of age. Body weight (B) of animals was recorded weekly. At various time points animals were euthanized, genitourinary tract (G) were weighed. Prostate tissue was subjected to immunohistochemical analyses for SV40-TAg, epithelial-mesenchymal transition (EMT), proliferation, neuroendocrine differentiation (NED) and apoptosis. Multiple organs were examined for drug toxicity and lungs were analyzed for metastasis. Results: TRAMP mice exhibit to high-grade prostatic intraepithelial neoplasia (PIN) by 12 weeks and progresses to poorly differentiated adeno-carcinoma by 30 weeks with distant metastasis to lungs. TET feeding did not show any considerable difference body weight loss profiles during the entire treatment regimen. At the time of necropsy, there was no evidence of edema, abnormal organ size or appearance in non-target organs. TET gavage group showed (p&amp;lt;0.005) lower G/B ratio compared to the PBS treated group. These findings clearly indicate that TET dosing is non-toxic and restricts the abnormal growth of the prostate in TRAMP mice. TET repress the EMT as well as NED transition and inhibits cell proliferation (p&amp;lt;0.005) by Ki-67 staining. Oral administration of TET inhibits PCa growth and progression by increases (p&amp;lt;0.005) apoptosis in tumor tissues. Further, TET inhibited metastasis as there was significant (p&amp;lt;0.005) decrease in metastasis to lungs in TET treated animals. Conclusion: Human achievable dose of TET treatment to TRAMP mice bearing prostate tumor, exhibited no-observed-adverse-effect-level in toxicology evaluations and also significantly inhibited tumor growth, progression, local invasion and distant metastasis involving suppression of tumor, and thus could have potential against human PCa. Citation Format: Hari K. Koul, Prakash Srinivasan Timiri Shanmugam, Praveen K. Jaiswal, Sweaty Koul. TET inhibits prostate cancer tumor growth, progression and metastasis in TRAMP mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5061. doi:10.1158/1538-7445.AM2017-5061

MP28-02 PHYSIOLOGICAL EVIDENCE OF DNA DAMAGE BY CARCINOGENS KNOWN TO BE PRESENT IN CHARRED AND PROCESSED MEATS (PHIP DNA ADDUCTS), IN A SMALL COHORT OF PROSTATE CANCER PATIENTS.

You have accessJournal of UrologyProstate Cancer: Markers I1 Apr 2017MP28-02 PHYSIOLOGICAL EVIDENCE OF DNA DAMAGE BY CARCINOGENS KNOWN TO BE PRESENT IN CHARRED AND PROCESSED MEATS (PHIP DNA ADDUCTS), IN A SMALL COHORT OF PROSTATE CANCER PATIENTS. Christopher Weight, Shun Xiao, Jingshu Guo, Byeong Hwa Yun, Badrinath Konety, Peter Villalta, Resha Tejpaul, Suprita Krishna, Paari Murugan, and Robert Turesky Christopher WeightChristopher Weight More articles by this author , Shun XiaoShun Xiao More articles by this author , Jingshu GuoJingshu Guo More articles by this author , Byeong Hwa YunByeong Hwa Yun More articles by this author , Badrinath KonetyBadrinath Konety More articles by this author , Peter VillaltaPeter Villalta More articles by this author , Resha TejpaulResha Tejpaul More articles by this author , Suprita KrishnaSuprita Krishna More articles by this author , Paari MuruganPaari Murugan More articles by this author , and Robert TureskyRobert Turesky More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.815AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Epidemiologic studies have reported an association between frequent consumption of well-done cooked meats and prostate cancer (PC) risk. Charred red meat and cooked processed meats are known to contain heterocyclic aromatic amine (HAA) carcinogens, such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) the most mass abundant HAA, and are linked to PC development in a rodent model. However, unambiguous physiochemical markers of DNA damage from these meat-derived carcinogens have not been identified in human samples to support the paradigm of HAA induced human prostate carcinogenesis. METHODS Thirty-five men with biopsy proven intermediate to high-risk PC underwent radical prostatectomy at University of Minnesota from Dec 2015-Aug 2016. After prostatectomy, both tumor bearing tissue and non-tumor bearing adjacent fresh tissue was analyzed for DNA adducts using a highly sensitive nano-LC-Orbitrap mass spectrometry method. We also analyzed formalin fixed paraffin embedded (FFPE) tissues from each patient. RESULTS Median age of the men with PC was 65 (range 45-78). Pathology demonstrated the following Gleason Scores (GS) and pathologic staging: GS= 6 in 1 patient (2.8%), GS=7 in 28 patients (80%) and GS=8-10 in 6 patients (17%) and 16 men (46%) were stage 2 and 19 men were stage 3 (54%). The PhIP DNA adduct was identified in 11 out of 35 patients, at levels ranging from 2 to 120 adducts per 109 nucleotides. PhIP DNA adducts also were recovered quantitatively from FFPE tissues. CONCLUSIONS Our data provide support to the epidemiological observations implicating PhIP as a DNA damaging agent that may contribute to the etiology of PC in humans. FFPE tissues can be used as a tissue source in DNA-adduct biomarker research using our mass spectrometry method. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e338 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Christopher Weight More articles by this author Shun Xiao More articles by this author Jingshu Guo More articles by this author Byeong Hwa Yun More articles by this author Badrinath Konety More articles by this author Peter Villalta More articles by this author Resha Tejpaul More articles by this author Suprita Krishna More articles by this author Paari Murugan More articles by this author Robert Turesky More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Physiological evidence of DNA damage by carcinogens known to be present in charred and processed meats (PhIP DNA adducts) in a small cohort of patients with prostate cancer.

e580 Background: Epidemiologic studies have reported an association between frequent consumption of well-done cooked meats and prostate cancer (PC) risk. Charred red meat and cooked processed meats are known to contain heterocyclic aromatic amine (HAA) carcinogens, such as 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP) the most mass abundant HAA, and are linked to PC development in a rodent model. However, unambiguous physiochemical markers of DNA damage from these meat-derived carcinogens have not been identified in human samples to support the paradigm of HAA induced human prostate carcinogenesis. Methods: Thirty-five men with biopsy proven intermediate to high-risk PC underwent radical prostatectomy at University of Minnesota from Dec 2015-Aug 2016. After prostatectomy, both tumor bearing tissue and non-tumor bearing adjacent fresh tissue was analyzed for DNA adducts using a highly sensitive nano-LC-Orbitrap mass spectrometry method. We also analyzed formalin fixed paraffin embedded (FFPE) tissues from each patient. Results: Median age of the men with PC was 65 (range 45-78). Pathology demonstrated the following Gleason Scores (GS) and pathologic staging: GS = 6 in 1 patient (2.8%), GS = 7 in 28 patients (80%) and GS = 8-10 in 6 patients (17%) and 16 men (46%) were stage 2 and 19 men were stage 3 (54%). The PhIP DNA adduct was identified in 11 out of 35 patients, at levels ranging from 2 to 120 adducts per 109 nucleotides. PhIP DNA adducts also were recovered quantitatively from FFPE tissues. Conclusions: Our data provide support to the epidemiological observations implicating PhIP as a DNA damaging agent that may contribute to the etiology of PC in humans. FFPE tissues can be used as a tissue source in DNA-adduct biomarker research using our mass spectrometry method

β-Carotene 9',10' Oxygenase Modulates the Anticancer Activity of Dietary Tomato or Lycopene on Prostate Carcinogenesis in the TRAMP Model.

The hypothesis that dietary tomato consumption or the intake of the carotenoid lycopene inhibits prostate cancer arose from epidemiologic studies and is supported by preclinical rodent experiments and in vitro mechanistic studies. We hypothesize that variation in activity of carotenoid cleavage enzymes, such as β-carotene 9',10'-oxygenase (BCO2), may alter the impact of dietary tomato and lycopene on prostate carcinogenesis and therefore examined this relationship in the TRAMP model. Starting at 3 weeks of age, TRAMP:Bco2+/+ and TRAMP:Bco2-/- mice were fed either AIN-93G control, or semipurified diets containing 10% tomato powder or 0.25% lycopene beadlets until 18 weeks of age. Both tomato- and lycopene-fed TRAMP:Bco2-/- mice had significantly greater serum concentrations of total, 5-cis, other cis, and all-trans lycopene than TRAMP:Bco2+/+ mice. Tomato- and lycopene-fed mice had a lower incidence of prostate cancer compared with the control-fed mice. Although Bco2 genotype alone did not significantly change prostate cancer outcome in the control AIN-93G-fed mice, the abilities of lycopene and tomato feeding to inhibit prostate carcinogenesis were significantly attenuated by the loss of Bco2 (Pinteraction = 0.0004 and 0.0383, respectively). Overall, dietary tomato and lycopene inhibited the progression of prostate cancer in TRAMP in a Bco2 genotype-specific manner, potentially implicating the anticancer activity of lycopene cleavage products. This study suggests that genetic variables impacting carotenoid metabolism and accumulation can impact anticancer activity and that future efforts devoted to understanding the interface between tomato carotenoid intake, host genetics, and metabolism will be necessary to clearly elucidate their interactive roles in human prostate carcinogenesis. Cancer Prev Res; 10(2); 161-9. ©2016 AACR.

Abstract 4327: Dietary tomato reduces castration-resistant prostate cancer progression in TRAMP mice

Abstract Epidemiological data support the hypothesis that consumption of diets rich in tomato products are associated with a reduced risk of prostate cancer. Castration-resistant prostate cancer (CRPC) represents the late and lethal phase of human prostate carcinogenesis, and is defined as cancer progression after surgical castration or pharmacologic reduction of serum testosterone through androgen deprivation therapy. Mechanisms involved in the transition to CRPC include cancer cells’ acquired capacity for androgen synthesis or activation of ligand-independent signaling. We have previously shown that dietary tomato can inhibit prostatic androgen signaling and expression of androgen biosynthetic genes, as well as reduce primary cancer incidence in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Therefore, we examined whether dietary tomato might be an effective inhibitor of CRPC progression in mice. We hypothesized that lifelong dietary intake of tomato, as well as dietary tomato intervention following castration, would reduce tumor burden and growth rate in a mouse model of CRPC. TRAMP mice were fed an AIN-93G diet (CON) for one week and then randomized to the CON diet (n = 28) or a similar diet with 10% w/w lyophilized tomato paste (TP; n = 27) from 4 wks of age until euthanization. A third group, modeling dietary intervention, consumed CON from 4 to 12 wks of age, and the 10% w/w lyophilized tomato paste diet from wk 12 until euthanization (TP-I; n = 25). All animals were castrated at 12 wks of age. Beginning at 10 wks of age, mice were monitored longitudinally with ultrasound for tumor detection, tumor volume estimation, and calculation of tumor growth rate. Serial 2D image slices were used to generate a 3D volume estimate. Mice were euthanized after 5 consecutive tumor scans, or if no tumor had been detected by 30 weeks of age. Tumor growth area under the curve (AUC) was reduced approximately 46% by tomato intervention (TP-I) and 27% by lifelong tomato consumption (TP). At euthanization, TP-I reduced tumor weight by approximately 26%. Additionally, incidence of gross metastases to distant organs (lung, liver, kidney) was strongly inhibited by TP-I, compared to CON (0% and 26%, respectively). TP diet reduced incidence of distant organ gross metastasis to &amp;lt;10%. The consumption of tomato products following castration inhibits CRPC progression in the TRAMP model. Our findings support the development of human studies of dietary tomato interventions in combination with anti-androgen therapy for men with advanced prostate cancer. Citation Format: Joshua W. Smith, Joe L. Rowles, Rita J. Miller, Steven K. Clinton, William D. O’Brien, John W. Erdman. Dietary tomato reduces castration-resistant prostate cancer progression in TRAMP mice. [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 4327.

Dietary Tomato Reduces Castration‐Resistant Prostate Cancer Burden in the TRAMP Model

Epidemiological evidence continues to support the hypothesis that consumption of diets rich in tomato products are associated with a reduced risk of prostate cancer, a relationship supported by studies in rodent models. Castration‐resistant prostate cancer (CRPC) represents the late and lethal phase of human prostate carcinogenesis, and is defined as cancer progression after surgical castration or pharmacologic reduction of serum testosterone through androgen deprivation therapy (ADT). One mechanism involved in the transition to CRPC is cancer cells’ acquired capacity for androgen synthesis. We have previously shown that dietary tomato can reduce prostatic expression of androgen biosynthetic genes. Therefore, we questioned whether dietary tomato might be effective in preventing or controlling the progression of CRPC. We hypothesized that lifelong dietary intake of tomato, as well as dietary tomato intervention following castration, would reduce tumor burden and growth rate in a mouse model of CRPC. TRAMP mice (3 weeks of age, n=79) were acclimated to a powdered, AIN‐93G diet (CON) for one week and then randomized to consume CON (n=28) or 10% w/w lyophilized tomato paste (TP; n=27) from 4 weeks of age until euthanization. A third group, modeling adjuvant dietary intervention, consumed CON from 4 weeks of age until 12 weeks of age, and then 10% w/w lyophilized tomato paste from week 12 until euthanization (TP‐I; n=25). All animals were castrated at 12 weeks of age. Beginning at 10 weeks of age, mice were monitored longitudinally with biweekly ultrasound scans for tumor detection. For each ultrasound scan, serial 2D image slices were used to generate a 3D volume measurement. Upon tumor detection, mice were switched from biweekly to weekly scans and imaged 4 additional times for volumetric tumor measurement and determination of tumor growth rate. Two criteria were implemented for euthanasia: after 5 tumor scans (detection + 4 weekly), or if no tumor had been detected by 30 weeks of age. Longitudinal tumor area under the curve (AUC), as measured by ultrasound, was reduced nearly 50% by tomato intervention (TP‐I) and approximately 25% by lifelong tomato consumption (TP). At euthanization, TP‐I, but not TP, reduced tumor weight approximately 30%. Both measures of tumor burden (tumor growth AUC and tumor weight at euthanization) were reduced by the adjuvant TP‐I, while only tumor growth AUC was decreased by lifelong TP. Observational studies have shown that the lycopene content of the tomato diets in the present study, in human equivalent dose, is both achievable and protective against prostate cancer. Previously, we have shown that lifelong tomato consumption reduces cancer incidence in TRAMP models of primary prostate cancer; current results suggest that pathways regulating primary and castration‐resistant prostatic carcinogenesis in the TRAMP model may be differentially impacted by lifelong tomato feeding. Future work should address efficacy of adjuvant dietary tomato with pharmacologic ADT to assess the potential for this approach to translate into clinical benefits for men with CRPC.Support or Funding InformationThis work is supported by the USDA NIFA Hatch project ILLU‐971‐334 and NIH R37 EB002641.

The cancer-promoting gene fatty acid-binding protein 5 (FABP5) is epigenetically regulated during human prostate carcinogenesis.

FABPs (fatty-acid-binding proteins) are a family of low-molecular-mass intracellular lipid-binding proteins consisting of ten isoforms. FABPs are involved in binding and storing hydrophobic ligands such as long-chain fatty acids, as well as transporting these ligands to the appropriate compartments in the cell. FABP5 is overexpressed in multiple types of tumours. Furthermore, up-regulation of FABP5 is strongly associated with poor survival in triple-negative breast cancer. However, the mechanisms underlying the specific up-regulation of the FABP5 gene in these cancers remain poorly characterized. In the present study, we determined that FABP5 has a typical CpG island around its promoter region. The DNA methylation status of the CpG island in the FABP5 promoter of benign prostate cells (PNT2), prostate cancer cells (PC-3, DU-145, 22Rv1 and LNCaP) and human normal or tumour tissue was assessed by bisulfite sequencing analysis, and then confirmed by COBRA (combined bisulfite restriction analysis) and qAMP (quantitative analysis of DNA methylation using real-time PCR). These results demonstrated that overexpression of FABP5 in prostate cancer cells can be attributed to hypomethylation of the CpG island in its promoter region, along with up-regulation of the direct trans-acting factors Sp1 (specificity protein 1) and c-Myc. Together, these mechanisms result in the transcriptional activation of FABP5 expression during human prostate carcinogenesis. Importantly, silencing of Sp1, c-Myc or FABP5 expression led to a significant decrease in cell proliferation, indicating that up-regulation of FABP5 expression by Sp1 and c-Myc is critical for the proliferation of prostate cancer cells.

Methylation of Integrin α4 and E-Cadherin Genes in Human Prostate Cancer.

Prostate cancer is the second most common malignancy in men worldwide. Abnormal epigenetic alterations such as DNA methylation and histone modification play an important role in tumor initiation, progression and regulation of cancer-related genes such as integrin α4 and E-cadherin. Expression of these genes was determined by semi-quantitative reverse transcriptase-PCR in prostate cancer cell lines, DU145 and PC3, before and after treatment with 5-aza-2-deoxycytidine and trichostatin A. Laser capture microdissection microscopy was used to obtain exclusively affected epithelial cells from prostate gland biopsies of 30 patients with prostate cancer and 40 with benign prostate hyperplasia. DNA bisulfite modifications followed by methylation-specific PCR were used to evaluate the promoter methylation status of E-cadherin and α4 integrin genes in extracted DNA from patients and aforementioned cell lines. The integrin α4 promoter in DU145 was fully methylated, whereas in PC3 cells, partial methylation was detected. E-cadherin was expressed in both cell lines; trichostatin A and 5-aza-2-deoxycytidine treatment had no effect on E-cadherin expression, however the combined treatment of both drugs or 5-aza-2-deoxycytidine alone increased integrin α4 expression. Integrin α4 and E-cadherin were hypermethylated in 66.6 % and 6.6 % of prostate cancer cases, respectively; no hypermethylation was observed in patients with benign prostate hyperplasia. These results together suggest that aberrant DNA methylation is one of the mechanisms involved in integrin α4 expression and may play an important role in human prostate carcinogenesis. In addition, the higher rate of integrin α4 gene methylation in prostate cancer patients elects it as a potential molecular tumor marker.

MLF1 interacting protein: a potential gene therapy target for human prostate cancer?

Here, we investigated the role of one gene that has been previously associated with human prostate carcinoma cells-myelodysplasia/myeloid leukemia factor 1 interacting protein (MLF1IP)-in order to better ascertain its role in human prostate carcinogenesis. The prostate cancer cell line PC-3 was lentivirally transfected to silence endogenous MLF1IP gene expression, which was confirmed by real-time quantitative PCR (RT-qPCR). Cellomics ArrayScan VTI imaging and MTT assays were conducted to assess cell proliferation. Cell cycle phase arrest and apoptosis were assayed by flow cytometry. Colony formation was assessed by fluorescence microscopy. MLF1IP gene expression was also analyzed by RT-qPCR in sixteen prostate cancer tissue samples and six healthy control prostate tissue samples from human patients. Cell proliferation was significantly inhibited in MLF1IP-silenced cells relative to control cells. G1 phase, S and G2/M phase cell counts were not significantly changed in MLF1IP-silenced cells relative to control cells. Apoptosis was significantly increased in MLF1IP-silenced cells, while MLF1IP-silenced cells displayed a significantly reduced number of cell colonies, compared to control cells. The 16 human prostate cancer tissue samples revealed no clear upregulation or downregulation in MLF1IP gene expression. MLF1IP significantly promotes prostate cancer cell proliferation and colony formation and significantly inhibits apoptosis without affecting cell cycle phase arrest. Further study is required to conclusively determine whether MLF1IP is upregulated in human prostate cancer tumors and to determine the precise cellular mechanism(s) for MLF1IP in prostate carcinogenesis.

Generation of Prostate Tumor–Initiating Cells Is Associated with Elevation of Reactive Oxygen Species and IL-6/STAT3 Signaling

How prostate cancer is initiated remains a topic of debate. In an effort to establish a human model of prostate carcinogenesis, we adapted premalignant human prostate EPT2-D5 cells to protein-free medium to generate numerous tight prostate spheres (D5HS) in monolayer culture. In contrast to EPT2-D5 cells, the newly generated D5HS efficiently formed large subcutaneous tumors and subsequent metastases in vivo, showing the tumorigenicity of D5HS spheres. A striking production of interleukin (IL)-6 mRNA and protein was found in D5HS cells. The essential roles of IL-6 and the downstream STAT3 signaling in D5HS tumor sphere formation were confirmed by neutralizing antibody, chemical inhibitors, and fluorescent pathway reporter. In addition, elevated reactive oxygen species (ROS) produced upon protein depletion was required for the activation of IL-6/STAT3 in D5HS. Importantly, a positive feedback loop was found between ROS and IL-6 during tumor sphere formation. The association of ROS/IL-6/STAT3 to the carcinogenesis of human prostate cells was further examined in xenograft tumors and verified by limiting dilution implantations. Collectively, we have for the first time established human prostate tumor-initiating cells based on physiologic adaption. The intrinsic association of ROS and IL-6/STAT3 signaling in human prostate carcinogenesis shed new light on this relationship and define therapeutic targets in this setting.

Formation of Human Prostate Epithelium Using Tissue Recombination of Rodent Urogenital Sinus Mesenchyme and Human Stem Cells

Progress in prostate cancer research is severely limited by the availability of human-derived and hormone-naïve model systems, which limit our ability to understand genetic and molecular events underlying prostate disease initiation. Toward developing better model systems for studying human prostate carcinogenesis, we and others have taken advantage of the unique pro-prostatic inductive potential of embryonic rodent prostate stroma, termed urogenital sinus mesenchyme (UGSM). When recombined with certain pluripotent cell populations such as embryonic stem cells, UGSM induces the formation of normal human prostate epithelia in a testosterone-dependent manner. Such a human model system can be used to investigate and experimentally test the ability of candidate prostate cancer susceptibility genes at an accelerated pace compared to typical rodent transgenic studies. Since Human embryonic stem cells (hESCs) can be genetically modified in culture using inducible gene expression or siRNA knock-down vectors prior to tissue recombination, such a model facilitates testing the functional consequences of genes, or combinations of genes, which are thought to promote or prevent carcinogenesis. The technique of isolating pure populations of UGSM cells, however, is challenging and learning often requires someone with previous expertise to personally teach. Moreover, inoculation of cell mixtures under the renal capsule of an immunocompromised host can be technically challenging. Here we outline and illustrate proper isolation of UGSM from rodent embryos and renal capsule implantation of tissue mixtures to form human prostate epithelium. Such an approach, at its current stage, requires in vivo xenografting of embryonic stem cells; future applications could potentially include in vitro gland formation or the use of induced pluripotent stem cell populations (iPSCs).

Abstract 1268: The role of the adaptive immune system in initiation and progression in two independent spontaneous mouse models for prostate cancer.

Abstract Increasing evidence from epidemiological and pathology studies indicates a role of the immune system in initiation and progression of multiple cancers, including prostate cancer. However, reports on the specific role of the immune system are contradictive since both suppression and acceleration of disease progression have been described. Overexpression of MYC and loss of PTEN are frequent genetic lesions in prostate cancer. It has been shown that these lesions induce chemokine expression, attraction of immune cells and subsequent angiogenesis and disease progression in cancer models. In this study we address the role of the adaptive immune system in prostate cancer progression in two independent spontaneous prostate cancer mouse models; the FVB/HiMYC mouse model in which prostate cancer formation is driven by transgenic expression of human MYC under control of the ARR2/probasin promoter, and the PB-Cre;PTENF/F mouse model in which prostate cancer formation is initiated by loss of PTEN expression. Both mouse models develop Prostatic Intraepithelial Neoplasia (PIN) from the age of 4 weeks on. FVB/HiMYC mice develop invasive carcinoma from the age of 24 weeks and PB-Cre;PTENF/F mice from the age of 12 weeks on. To address the functional significance of lymphocytes in prostate cancer development, FVB/HiMYC and PB-Cre;PTENF/F were crossed to lymphocyte deficient RAG-1−/− mice. Preliminary data suggest that both mouse models crossed to RAG-1−/− have a longer latency of invasive carcinoma development and less extensive lesions than RAG-1+/− mice, suggesting an important role of the adaptive immune system in prostate cancer initiation and/or progression. Marked inflammation and increased nuclear BrdU incorporation was found in concert with prostate cancer development using immunohistochemistry. Flow cytometry confirmed an increase in CD45 positive cells in the prostate, which was not observed in blood. Studies to identify the lymphocyte population with a key role in prostate cancer development and to dissect the exact mechanism of growth promotion are currently ongoing. In addition, we will verify whether the identified immune cells and soluble mediators in the in vivo models are also found in human prostate cancer samples. In conclusion: Our study provides insight into the role of the adaptive immune system in prostate cancer development. These data might serve as a basis to develop intervention strategies that intersect with the supportive role of the immune system in human prostate carcinogenesis. Citation Format: Monique H.M Melis, Johan van Burgsteden, Hester J.T. van Zeeburg, John Zevenhoven, Ji-Ying Song, Karin E. de Visser, Andre M. Bergman. The role of the adaptive immune system in initiation and progression in two independent spontaneous mouse models for prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1268. doi:10.1158/1538-7445.AM2013-1268

Human α2β1HI CD133+VE Epithelial Prostate Stem Cells Express Low Levels of Active Androgen Receptor

Stem cells are thought to be the cell of origin in malignant transformation in many tissues, but their role in human prostate carcinogenesis continues to be debated. One of the conflicts with this model is that cancer stem cells have been described to lack androgen receptor (AR) expression, which is of established importance in prostate cancer initiation and progression. We re-examined the expression patterns of AR within adult prostate epithelial differentiation using an optimised sensitive and specific approach examining transcript, protein and AR regulated gene expression. Highly enriched populations were isolated consisting of stem (α2β1 HI CD133+VE), transiently amplifying (α2β1 HI CD133–VE) and terminally differentiated (α2β1 LOW CD133–VE) cells. AR transcript and protein expression was confirmed in α2β1 HI CD133+VE and CD133–VE progenitor cells. Flow cytometry confirmed that median (±SD) fraction of cells expressing AR were 77% (±6%) in α2β1 HI CD133+VE stem cells and 68% (±12%) in α2β1 HI CD133–VE transiently amplifying cells. However, 3-fold lower levels of total AR protein expression (peak and median immunofluorescence) were present in α2β1 HI CD133+VE stem cells compared with differentiated cells. This finding was confirmed with dual immunostaining of prostate sections for AR and CD133, which again demonstrated low levels of AR within basal CD133+VE cells. Activity of the AR was confirmed in prostate progenitor cells by the expression of low levels of the AR regulated genes PSA, KLK2 and TMPRSS2. The confirmation of AR expression in prostate progenitor cells allows integration of the cancer stem cell theory with the established models of prostate cancer initiation based on a functional AR. Further study of specific AR functions in prostate stem and differentiated cells may highlight novel mechanisms of prostate homeostasis and insights into tumourigenesis.

Dietary Carcinogen 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine–Induced Prostate Carcinogenesis in CYP1A-Humanized Mice

To develop a relevant mouse model for prostate cancer prevention research, we administered a dietary carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), to CYP1A-humanized mice. In comparison with mouse Cyp1a2, human CYP1A2 preferentially activates PhIP to a proximate carcinogen. Following a single oral dose of PhIP (200 mg/kg body weight), we observed inflammation, atrophy of acini, low-grade prostatic intraepithelial neoplasia (PIN; after 20 weeks), and high-grade PIN (HgPIN; after 30 to 50 weeks) in dorsolateral, ventral, and coagulating anterior prostate glands of these mice. These lesions were androgen receptor positive and featured the loss of expression of the basal cell marker p63 and the tumor suppressor PTEN. Similar to human prostate carcinogenesis, glutathione S-transferase P1 (GSTP1) expression was lost or partially lost in HgPIN. E-Cadherin expression was also lost in HgPIN. The expression of DNA methyltransferase 1 was elevated, possibly to enhance promoter hypermethylation for the silencing of GSTP1 and E-cadherin. Prostate carcinogenesis was promoted by a high-fat stress diet, resulting in HgPIN that developed earlier and in advanced lesions displayed features consistent with carcinoma in situ. This dietary carcinogen-induced prostate cancer model, recapitulating important features of early human prostate carcinogenesis, constitutes a new experimental system for prostate cancer research.

SPRY2 loss enhances ErbB trafficking and PI3K/AKT signalling to drive human and mouse prostate carcinogenesis

Loss of SPRY2 and activation of receptor tyrosine kinases are common events in prostate cancer (PC). However, the molecular basis of their interaction and clinical impact remains to be fully examined. SPRY2 loss may functionally synergize with aberrant cellular signalling to drive PC and to promote treatment-resistant disease. Here, we report evidence for a positive feedback regulation of the ErbB-PI3K/AKT cascade by SPRY2 loss in in vitro as well as pre-clinical in vivo models and clinical PC. Reduction in SPRY2 expression resulted in hyper-activation of PI3K/AKT signalling to drive proliferation and invasion by enhanced internalization of EGFR/HER2 and their sustained signalling at the early endosome in a PTEN-dependent manner. This involved p38 MAPK activation by PI3K to facilitate clathrin-mediated ErbB receptor endocytosis. Finally, in vitro and in vivo inhibition of PI3K suppressed proliferation and invasion, supporting PI3K/AKT as a target for therapy particularly in patients with PTEN-haploinsufficient-, low SPRY2- and ErbB-expressing tumours. In conclusion, SPRY2 is an important tumour suppressor in PC since its loss drives the PI3K/AKT pathway via functional interaction with the ErbB system.