Evidence that EZH2 Deregulation is an Actionable Therapeutic Target for Prevention of Prostate Cancer.

Chemoprevention trials for prostate cancer by androgen receptor or androgen synthesis inhibition have proven ineffective. Recently, it has been demonstrated that the histone methlytransferase, EZH2 is deregulated in mouse and human high-grade prostatic intraepithelial neoplasia (HG-PIN). Using preclinical mouse and human models of prostate cancer, we demonstrate that genetic and chemical disruption of EZH2 expression and catalytic activity reversed the HG-PIN phenotype. Furthermore, inhibition of EZH2 function was associated with loss of cellular proliferation and induction of Tp53-dependent senescence. Together, these data provide provocative evidence for EZH2 as an actionable therapeutic target toward prevention of prostate cancer.

Grape Powder Supplementation Attenuates Prostate Neoplasia Associated with Pten Haploinsufficiency in Mice Fed High-Fat Diet.

SCOPE: Previous studies have identified potent anticancer activities of polyphenols in preventing prostate cancer. The aim of the current study is to evaluate the chemopreventive potential of grape powder (GP) supplemented diets in genetically predisposed and obesity-provoked prostate cancer. METHODS AND RESULTS: Prostate-specific Pten heterozygous (Pten+/f ) transgenic mice are fed low- and high-fat diet (LFD and HFD, respectively) supplemented with 10% GP for 33 weeks, ad libitum. Prostate tissues are characterized using immunohistochemistry and western blots, and sera are analyzed by ELISA and qRT-PCR. Pten+/f mice fed LFD and HFD supplemented with 10% GP show favorable histopathology, significant reduction of the proliferative rate of prostate epithelial cells (Ki67), and rescue of PTEN expression. The most potent protective effect of GP supplementation is detected against HFD-induced increase in inflammation (IL-1ß; TGF-ß1), activation of cell survival pathways (Akt, AR), and angiogenesis (CD31) in Pten+/f mice. Moreover, GP supplementation reduces circulating levels of oncogenic microRNAs (miR-34a; miR-22) in Pten+/f mice. There are no significant changes in body weight and food intake in GP supplemented diet groups. CONCLUSIONS: GP diet supplementation can be a beneficial chemopreventive strategy for obesity-related inflammation and prostate cancer progression. Monitoring serum miRNAs can facilitate the non-invasive evaluation of chemoprevention efficacy.

Precursor Lesions of Urologic Malignancies.

CONTEXT: - Precursor lesions of urologic malignancies are established histopathologic entities, which are important not only to recognize for clinical purposes, but also to further investigate at the molecular level in order to gain a better understanding of the pathogenesis of these malignancies. OBJECTIVE: - To provide a brief overview of precursor lesions to the most common malignancies that develop within the genitourinary tract with a focus on their clinical implications, histologic features, and molecular characteristics. DATA SOURCES: - Literature review from PubMed, urologic pathology textbooks, and the 4th edition of the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. All photomicrographs were taken from cases seen at Weill Cornell Medicine or from the authors' personal slide collections. CONCLUSIONS: - The clinical importance and histologic criteria are well established for the known precursor lesions of the most common malignancies throughout the genitourinary tract, but further investigation is warranted at the molecular level to better understand the pathogenesis of these lesions. Such investigation may lead to better risk stratification of patients and potentially novel treatments.

Ornithine Decarboxylase Is Sufficient for Prostate Tumorigenesis via Androgen Receptor Signaling.

Increased polyamine synthesis is known to play an important role in prostate cancer. We aimed to explore its functional significance in prostate tumor initiation and its link to androgen receptor (AR) signaling. For this purpose, we generated a new cell line derived from normal epithelial prostate cells (RWPE-1) with overexpression of ornithine decarboxylase (ODC) and used it for in vitro and in vivo experiments. We then comprehensively analyzed the expression of the main metabolic enzymes of the polyamine pathway and spermine abundance in 120 well-characterized cases of human prostate cancer and high-grade prostate intraepithelial neoplasia (HGPIN). Herein, we show that the ODC-overexpressing prostate cells underwent malignant transformation, revealing that ODC is sufficient for de novo tumor initiation in 94% of injected mice. This oncogenic capacity was acquired through alteration of critical signaling networks, including AR, EIF2, and mTOR/MAPK. RNA silencing experiments revealed the link between AR signaling and polyamine metabolism. Human prostate cancers consistently demonstrated up-regulation of the main polyamine enzymes analyzed (ODC, polyamine oxidase, and spermine synthase) and reduction of spermine. This phenotype was also dominant in HGPIN, rendering it a new biomarker of malignant transformation. In summary, we report that ODC plays a key role in prostate tumorigenesis and that the polyamine pathway is altered as early as HGPIN.

Stromal epigenetic dysregulation is sufficient to initiate mouse prostate cancer via paracrine Wnt signaling.

Carcinomas most often result from the stepwise acquisition of genetic alterations within the epithelial compartment. The surrounding stroma can also play an important role in cancer initiation and progression. Given the rare frequencies of genetic events identified in cancer-associated stroma, it is likely that epigenetic changes in the tumor microenvironment could contribute to its tumor-promoting activity. We use Hmga2 (High-mobility group AT-hook 2) an epigenetic regulator, to modify prostate stromal cells, and demonstrate that perturbation of the microenvironment by stromal-specific overexpression of this chromatin remodeling protein alone is sufficient to induce dramatic hyperplasia and multifocal prostatic intraepithelial neoplasia lesions from adjacent naïve epithelial cells. Importantly, we find that this effect is predominantly mediated by increased Wnt/ß-catenin signaling. Enhancement of Hmga2-induced paracrine signaling by overexpression of androgen receptor in the stroma drives frank murine prostate adenocarcinoma in the adjacent epithelial tissues. Our findings provide compelling evidence for the critical contribution of epigenetic changes in stromal cells to multifocal tumorigenesis.

High-fat diet obesity associated with insulin resistance increases cell proliferation, estrogen receptor, and PI3K proteins in rat ventral prostate.

In this study, we evaluated the effects of obesity and insulin resistance induced by a high-fat diet on prostate morphophysiology, focusing on cell proliferation, expression of androgen (AR) and estrogen receptors (ER) and proteins of the insulin signaling pathway. Adult male Wistar rats were fed a high-fat diet (20% fat) for 15 weeks, whereas control animals received a balanced diet (4% fat). Both groups were then divided and treated for 2 weeks with 1 mg/kg body weight/day of the aromatase inhibitor letrozole or vehicle only. The ventral prostate was analyzed with immunohistochemical, histopathological, stereological, and Western blotting methods. Obese rats showed insulin resistance, hyperinsulinemia, and reduced plasma testosterone levels. The incidence of prostatic intraepithelial neoplasia (PIN) was 2.7 times higher in obese rats and affected 0.4% of the gland compared with 0.1% PIN areas found in control rats. Obesity doubled cell proliferation in both prostate epithelium and stroma. AR content decreased in the prostate of obese rats and estrogen receptor beta (ERß) increased in this group. Protein levels of insulin receptor substrate 1 and protein kinase B diminished in the obese group, whereas phosphatidylinositol 3-kinase (PI3K) increased significantly. Most structural changes observed in the prostate of obese rats normalized after letrozole treatment, except for increased stromal cell proliferation and ERß expression, which might be associated with insulin resistance. This experimental model of obesity and insulin resistance induced by a high-fat diet increases cell proliferation in rat prostate. Such alterations are associated with decreased levels of AR and increased ERß and PI3K proteins. This change can facilitate the establishment of proliferative lesions in rat prostate.

A joint effect of new Western diet and retinoid X receptor α prostate-specific knockout with development of high-grade prostatic intraepithelial neoplasia in mice--a preliminary study.

BACKGROUND: The "New Western-style Diet" (NWD) characterized by high in fat and low in fiber, vitamin D, calcium, and methyl donors--are considered as a risk factor for prostate cancer. Previous studies have shown that premalignant lesions of human prostate have decreased expression of the Retinoid X Receptor alpha (RXRα). This study was to determine the effect of diet in RXRα knockout mice in developing high-grade prostate intraepithelial neoplasia (mPIN). METHODS: Male mice (n = 54) with or without the RXRα prostate null mutation were fed either NWD or AIN-76A control diet for 10 months; prostates were harvested at 11 months of age and examined for prostate mPIN. RESULTS: mPIN was seen in 79% of RXRα prostate null mice fed NWD (n = 19), 30.8% RXRα prostate null mice fed AIN-76A (n = 13), 42.9% RXRα wild-type mice fed NWD (n = 14), and 12.5% RXRα wild-type mice fed AIN-76A (n = 8). Unconditional Logistic analysis showed a significant joint effect of NWD and RXRα status in developing mPIN 26.3 (95% CI: 2.5-280), but interaction was not significant owing to the small sample size 1.6 (0.09-27.7, P = 0.7441). CONCLUSION: This study provides preliminary data to support a joint RXRα-diet effect in prostate carcinogenesis.

The effect Akt2 deletion on tumor development in Pten(+/-) mice.

The serine/threonine kinase Akt is frequently activated in human cancers and is considered an attractive therapeutic target. However, the relative contributions of the different Akt isoforms to tumorigenesis, and the effect of their deficiencies on cancer development are not well understood. We had previously shown that Akt1 deficiency is sufficient to markedly reduce the incidence of tumors in Pten(+/-) mice. Particularly, Akt1 deficiency inhibits endometrial carcinoma and prostate neoplasia in Pten(+/-) mice. Here, we analyzed the effect of Akt2 deficiency on the incidence of tumors in Pten(+/-) mice. Relative to Akt1, Akt2 deficiency had little-to-no effect on the incidence of prostate neoplasia, endometrial carcinoma, intestinal polyps and adrenal lesions in Pten(+/-) mice. However, Akt2 deficiency significantly decreased the incidence of thyroid tumors in Pten(+/-), which correlates with the relatively high level of Akt2 expression in the thyroid. Thus, unlike Akt1 deletion, Akt2 deletion is not sufficient to markedly inhibit tumorigenesis in Pten(+/-) mice in most tested tissues. The relatively small effect of Akt2 deletion on the inhibition of tumorigenesis in Pten(+/-) mice could be explained, in part, by an insufficient decrease in total Akt activity, due to the relatively lower Akt2 versus Akt1 expression, and relatively high blood insulin levels in Pten(+/-)Akt2(-/-) mice. The relatively high blood insulin levels in Pten(+/-)Akt2(-/-) mice may elevate the activity of Akt1, and possibly Akt3, thus, limiting the reduction of total Akt activity and preventing this activity from dropping to a threshold level required to inhibit tumorigenesis.

Ron receptor overexpression in the murine prostate induces prostate intraepithelial neoplasia.

Previous studies have shown that the Ron receptor is overexpressed in prostate cancer and Ron expression increases with disease severity in humans and the mouse TRAMP model. Here, the causal role of Ron overexpression in the murine prostate was examined in the development and progression of prostate cancer. Transgenic mouse strains were generated which selectively overexpressed Ron in the prostate epithelium and prostate histopathology was evaluated and compared to wild type controls. Ron overexpression led to the development of prostate intraepithelial neoplasia (mPIN) with local invasion and was associated with increases in prostate cell proliferation and decreases in cell death.

[Influence of sodium selenite on carcinogenesis of the prostate and other organs induced by methylnitrosourea and testosterone in rats].

Influence of selenium on induced carcinogenesis of the prostate and other organs was studied in male Wistar rats. Carcinogenesis was induced (68) by using our modification of a combined double-stage model including surgical castration, single administration of N-methyl-N-nitrosourea (MNU) and long-term promotion by a mix of testosterone ethers (MTE). Seven days after MNU injection the rats were randomized to form 2 groups. Controls were fed drinking water while the study group - water containing sodium selenite 4mg/l, daily - till the end of the experiment. Controls (12) were not exposed to any treatment. They were followed up for 55 weeks until sacrificed. Apparent benign prostatic hyperplasia developed in rats subjected to castration, MNU and MTE. Also, such precancerous lesions as prostatic intraepithelial neoplasia (PIN) and prostate cancer including metastatic one were detected. Malignant lymphoma, other than in target tissues, was the most frequent. Prostate pathological changes and lymphomas were not registered in intact rats. Unlike rats treated with MNU and MTE and fed untreated drinking water, selenium did not influence significantly the development of prostate intraepithelial neoplasia but reduced multiplicity of prostate cancer by 44.6%. Simultaneously, the incidence of induced malignant lymphomas decreased by 26.4%.

Diet and prostate cancer - a holistic approach to management.

There is now increasing evidence from epidemiologic surveys and from laboratory, intervention, and case-control studies that diet and lifestyle plays a crucial role in prostate cancer biology and tumorigenesis. This applies to both the development and progression of prostate cancer, although in many cases the specific initiating factors in the diet are poorly understood. Conversely, many nutrients and herbs also show significant promise in helping to treat prostate cancer by slowing progression and reducing recurrence, ultimately reducing the risk of morbidity and mortality from the disease. Furthermore for all grades of prostate cancer, nutritional interventions complement conventional treatment to improve response and quality of life. Slowing or even reversing the progression of, high-grade prostate intraepithelial neoplasia [HGPIN]). with chemo-preventative agents could be the best primary defense against prostate cancer, preventing it from occurring in the first place. The information given in this review about prostate cancer chemoprevention summarizes the key evidence for the role of different dietary components and their effect on prostate cancer prevention and progression. Most nutritional chemoprevention agents also have the added benefit of being beneficial for the cardiovascular system, bone health and for the prevention of other cancers.

SCRIB expression is deregulated in human prostate cancer, and its deficiency in mice promotes prostate neoplasia.

Loss of cellular polarity is a hallmark of epithelial cancers, raising the possibility that regulators of polarity have a role in suppressing tumorigenesis. The Scribble complex is one of at least three interacting protein complexes that have a critical role in establishing and maintaining epithelial polarity. In human colorectal, breast, and endometrial cancers, expression of the Scribble complex member SCRIB is often mislocalized and deregulated. Here, we report that Scrib is indispensable for prostate homeostasis in mice. Scrib heterozygosity initiated prostate hyperplasia, while targeted biallelic Scrib loss predisposed mice to prostate intraepithelial neoplasia. Mechanistically, Scrib was shown to negatively regulate the MAPK cascade to suppress tumorigenesis. Further analysis revealed that prostate-specific loss of Scrib in mice combined with expression of an oncogenic Kras mutation promoted the progression of prostate cancer that recapitulated the human disease. The clinical significance of the work in mice was highlighted by our observation that SCRIB deregulation strongly correlated with poor survival in human prostate cancer. These data suggest that the polarity network could provide a new avenue for therapeutic intervention.

Role of autonomous androgen receptor signaling in prostate cancer initiation is dichotomous and depends on the oncogenic signal.

The steroid hormone signaling axis is thought to play a central role in initiation and progression of many hormonally regulated epithelial tumors. It is unclear whether all cancer-initiating signals depend on an intact hormone receptor signaling machinery. To ascertain whether cell autonomous androgen receptor (AR) is essential for initiation of prostate intraepithelial neoplasia (PIN), the response of AR-null prostate epithelia to paracrine and cell autonomous oncogenic signals was assessed in vivo by using the prostate regeneration model system. Epithelial-specific loss of AR blocked paracrine FGF10-induced PIN, whereas the add back of exogenous AR restored this response. In contrast, PIN initiated by cell-autonomous, chronic-activated AKT developed independent of epithelial AR signaling. Our findings demonstrate a selective role for AR in the initiation of PIN, dependent on the signaling pathways driving tumor formation. Insights into the role of hormone receptor signaling in the initiation of epithelial tumors may help define this axis as a target for chemoprevention of carcinomas.

Exposure to ethinylestradiol during prenatal development and postnatal supplementation with testosterone causes morphophysiological alterations in the prostate of male and female adult gerbils.

Steroids perform significant functions in prostatic development and growth, so that interferences of this equilibrium may predispose the gland to the development of diseases during the life. Embryonic and neonatal exposure to xenoestrogens, many of them with endocrine-disrupting potential, has been related to the induction of disturbances in reproductive system organs. Thus, this study aimed to analyse morphological and immunocytochemical aspects of prostate in both male and female adult gerbils either exposed to ethinylestradiol during the prenatal phase (pregnant females received 10 µg/kg, by gavage) (EE group) or exposed to testosterone (1 mg/kg) during the postnatal period (EE/T group). Serological analysis revealed a rise in estradiol levels in adult males and females of the EE group. A higher incidence of prostatic intraepithelial neoplasia (PIN) was observed in the male and female prostate of the treated groups, besides an increase in collagen and reticular fibres. Immunocytochemistry showed an increase in prostatic epithelial cells immunoreactive to AR and a presence of a smooth muscle layer, evidenced by α actin, in injured regions this way absent in prostatic epithelial buds. These pieces of evidence suggest that the alterations verified in the prostate in adulthood of both sexes may be due to the high oestrogen levels. Either males or females of the EE/T group showed normalized estradiol levels, although prostatic lesions could be observed. While the prostatic gland of male gerbils was more affected than the female prostate, this study showed that the exposure to EE during this critical period of development disrupts the prostate of both sexes in terms of prostatic lesions.

The associations between statin use and prostate cancer screening, prostate size, high-grade prostatic intraepithelial neoplasia (PIN), and prostate cancer.

OBJECTIVE: Prior studies report statins may reduce the risk of advanced prostate cancer. This study investigates the association between statin use and the likelihood of having a PSA or DRE test, blood PSA levels, prostate volume, and the severity of lower urinary tract symptoms. We also describe the association between statin use and prostate cancer and high-grade prostatic intraepithelial neoplasia (PIN) before and after controlling for prostate cancer screening indices associated with statin use. METHODS: The Nashville Men's Health Study used a multicenter, rapid recruitment protocol to collect clinical, biologic, behavioral, and body measurement data from 2,148 men 40 years or older scheduled for diagnostic prostate biopsy. Medication use and other data were ascertained by research survey, clinical interview, and chart review. RESULTS: Approximately 37% of participants were taking a statin. Statin use was significantly associated with a 12% lower PSA levels and 8% smaller prostate volume after controlling for age, race, BMI, WHR, aspirin use, and other comorbidity. Simvastatin was more strongly associated with prostate volume, while atorvastatin was associated with PSA. Statin use was marginally associated with increasing PSA test frequency among men with undiagnosed cancer. Statin use was not associated with the frequency or results of digital rectal exams, lower urinary tract symptom severity, high-grade (Gleason > 6) prostate cancer (OR = 0.95 (0.73, 1.24)), low-grade (Gleason = 6) prostate cancer (OR = 1.11 (0.86, 1.42)) or PIN (OR = 0.82, (0.57, 1.17)). Additional control for the number of prior PSA tests, PSA levels, and prostate volume did not alter these results. CONCLUSION: These results suggest selective referral for biopsy associated with statin use is an essential element to address in further understanding the potential for statins to prevent prostate cancer.

A constitutively activated form of the p110beta isoform of PI3-kinase induces prostatic intraepithelial neoplasia in mice.

Recent work has shown that ablation of p110beta, but not p110alpha, markedly impairs tumorigenesis driven by loss of phosphatase and tensin homolog (PTEN) in the mouse prostate. Other laboratories have reported complementary data in human prostate tumor lines, suggesting that p110beta activation is necessary for tumorigenesis driven by PTEN loss. Given the multiple functions of PTEN, we wondered if p110beta activation also is sufficient for tumorigenesis. Here, we report that transgenic expression of a constitutively activated p110beta allele in the prostate drives prostate intraepithelial neoplasia formation. The resulting lesions are similar to, but are clearly distinct from, the ones arising from PTEN loss or Akt activation. Array analyses of transcription in multiple murine prostate tumor models featuring PI3K/AKT pathway activation allowed construction of a pathway signature that may be useful in predicting the prognosis of human prostate tumors.

SENP1 induces prostatic intraepithelial neoplasia through multiple mechanisms.

SUMOylation has been shown to modulate DNA replication/repair, cell cycle progression, signal transduction, and the hypoxic response. SUMO (small ubiquitin-like modifier)-specific proteases regulate SUMOylation, but how changes in the expression of these proteases contribute to physiological and/or pathophysiological events remains undefined. Here, we show that SENP1 (sentrin/SUMO-specific protease 1) is highly expressed in human prostate cancer specimens and correlates with hypoxia-inducing factor 1alpha (HIF1alpha) expression. Mechanistic studies in a mouse model indicate that androgen-driven expression of murine SENP1 leads to HIF1alpha stabilization, enhanced vascular endothelial growth factor production, and angiogenesis. Further pathological assessment of the mouse indicates that SENP1 overexpression induces transformation of the normal prostate gland and gradually facilitates the onset of high-grade prostatic intraepithelial neoplasia. Consistent with cell culture studies, SENP1 enhances prostate epithelial cell proliferation via modulating the androgen receptor and cyclin D(1). These results demonstrate that deSUMOylation plays a critical role in prostate pathogenesis through induction of HIF1alpha-dependent angiogenesis and enhanced cell proliferation.

[Prostatic inflammation and prostate cancer]. / Prostatitis und Prostatakarzinom.

Chronic inflammation seems of importance in multiple types of cancer. Numerous reports have revealed a potential link between chronic prostatatic inflammation and prostate cancer. The aim of this paper is to review the epidemiological, moprphological, molecular and clinical aspects of prostattic inflammation and prostate cancer.

Induction of prostatic intraepithelial neoplasia and modulation of androgen receptor by ETS variant 1/ETS-related protein 81.

ETS variant 1 (ETV1), also known as ETS-related protein 81, is overexpressed in prostate tumors, but whether and how this transcription factor affects tumorigenesis has remained elusive. Here, we show that ETV1 is primarily overexpressed in the most aggressive human prostate tumors. Transgenic ETV1 mice developed prostatic intraepithelial neoplasia as well as hyperplasia/neoplasia in seminal vesicles. Moreover, ETV1 cooperated with the androgen receptor (AR) to bind to the prostate-specific antigen enhancer and stimulate gene transcription. Consistent with its ability to physically interact with AR, ETV1 rendered an ETV1 binding site-driven reporter androgen inducible, and, on the other hand, ETV1 super-induced transcription from an AR binding site on androgen stimulation. In conclusion, our study substantiates that ETV1 overexpression is an underlying cause in the development of prostate and possibly also seminal vesicle cancer. Its interaction with and activation of AR provides a molecular mechanism on how ETV1 exerts its deleterious function. Thus, inhibiting ETV1 or blocking its interaction with AR may represent novel strategies in prostate cancer therapy.

Increased endogenous estrogen synthesis leads to the sequential induction of prostatic inflammation (prostatitis) and prostatic pre-malignancy.

Prostatitis causes substantial morbidity to men, through associated urinary symptoms, sexual dysfunction, and pelvic pain; however, 90% to 95% of cases have an unknown etiology. Inflammation is associated with the development of carcinoma, and, therefore, it is imperative to identify and study the causes of prostatitis to improve our understanding of this disease and its role in prostate cancer. As estrogens cause prostatic inflammation, here we characterize the murine prostatic phenotype induced by elevated endogenous estrogens due to aromatase overexpression (AROM+). Early-life development of the AROM+ prostate was normal; however, progressive changes culminated in chronic inflammation and pre-malignancy. The AROM+ prostate was smaller at puberty compared with wild-type controls. Mast cell numbers were significantly increased at puberty and preceded chronic inflammation, which emerged by 40 weeks of age and was characterized by increased mast cell, macrophage, neutrophil, and T-lymphocyte numbers. The expression of key inflammatory mediators was also significantly altered, and premalignant prostatic intraepithelial neoplasia lesions emerged by 52 weeks of age. Taken together, these data link estrogens to prostatitis and premalignancy in the prostate, further implicating a role for estrogen in prostate cancer. These data also establish the AROM+ mouse as a novel, non-bacterial model for the study of prostatitis.