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-1β; TGF-β1), 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.

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.

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.

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.

[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%.

Histopathological evidence for an association of inflammation with ductal pin-like lesions but not with ductal adenocarcinoma in the prostate of the noble rat

BACKGROUND

Chronic inflammation may contribute to the development of prostate cancer. The goal of this study was to determine the possible association of prostatic inflammation, prostatic intraepithelial neoplasia (PIN)-like lesion, and prostate cancer, and to assess the androgen and estrogen dependency of the early steps of carcinogenesis.

METHODS

Noble rats were treated with testosterone and estradiol implants for 13, 18, or 26 weeks. Hormone dependency of the lesions was studied in a subset of animals by removing hormone implants for 3 weeks after 15 weeks treatment time.

RESULTS

After treatment for 13 weeks, acute and chronic inflammation was found in the dorsolateral prostate lobes and both inflammation and PIN-like lesions were present in the periurethal area of the prostate in all animals (n = 8). Following hormone exposure for 18 and 26 weeks, inflammation in the prostate remained, and adenocarcinomas in the periurethal prostate area with no adjacent inflammation were observed in all 18 animals studied. When both hormone implants were removed after 15 weeks, PIN-like lesions progressed further to adenocarcinoma only in two of seven animals. When only the estradiol implants were removed, three of five animals developed adenocarcinomas.

CONCLUSIONS

Even though adenocarcinomas were not morphologically associated with inflammation, PIN-like lesions preceding adenocarcinoma were found in close association with inflammation, pointing towards a possible initiator role of inflammation in the early steps of prostatic carcinogenesis. Further, these results indicate that both androgens and estrogens together play a significant role in the induction of inflammation and prostatic cancer in this model.

Prostate growth and inflammation

INTRODUCTION

There is emerging evidence that prostatic inflammation may contribute to prostate growth either in terms of hyperplastic (BPH) or neoplastic (PC) changes. Inflammation is thought to incite carcinogenesis by causing cell and genome damage, promoting cellular turnover.

METHODS

We reviewed our personal experience and the international recent literature on the clinical data supporting a role of inflammation on BPH and PC growth and progression.

RESULTS

BPH: Among those patients with self-reported prostatitis, 57% had a history of BPH. MTOPS study showed that men with inflammation had a significantly higher risk of BPH progression and acute urinary retention. We showed that the use of a COX-2 inhibitor in combination with a 5 alpha reductase inhibitor could increase the apoptotic index in BPH tissue. Prostate cancer: A PCR-based analysis of bacterial colonization in PC specimens and normal prostate tissue showed highly suggestive correlation of bacterial colonization and chronic inflammation with a diagnosis of PC. Evidence from genetic studies support the hypothesis that prostate inflammation may be a cause of prostate cancer. De Marzo proposed that proliferative inflammatory atrophy (PIA) is a precursor to PIN and cancer.

CONCLUSION

The concept that inflammation can promote prostate growth either in terms of BPH and PC risk remains highly suggestive.

Glutamine tract length of human androgen receptors affects hormone-dependent and -independent prostate cancer in mice

The androgen receptor (AR) is involved in the initiation and progression of prostate cancer and its transition to androgen independence. Genetic variation in AR may contribute to disease risk and has been studied for a polymorphic N-terminal glutamine (Q) tract that shows population heterogeneity. While the length of this tract is known to affect AR in vitro, association with disease is complicated by genetic and environmental factors that have led to discordant epidemiological findings. To clarify the effect of Q tract polymorphism on prostate cancer, we created mice bearing humanized AR genes (h/mAr) varying in Q tract length. ARs with short Q tracts (12Q), which are transcriptionally more active, induce earlier disease in the transgene-induced TRAMP prostate cancer model than alleles with median (21Q) or long (48Q) tracts. Disease length varies within each genotype, with greater differentiation and AR expression in slower growing tumors. Remarkably, following androgen ablation, Q tract length has effects that are also allele-dependent and in directions opposite to those in hormone intact mice. Differences in AR activity conferred by Q tract length thus appear to direct distinct pathways of androgen-independent as well as androgen-dependent progression, and highlight substantial risk that may be associated with alterations in the androgen axis. This AR allelic series in humanized mice provides an experimental paradigm to dissect the role of AR in prostate cancer initiation and progression, to model response to treatment and to test therapies targeted specifically to the human AR.

Chronic inflammation is negatively associated with prostate cancer and high-grade prostatic intraepithelial neoplasia on needle biopsy

Tissue inflammation has been linked to cancer in several disease models. We tested the association between chronic inflammation and prostate cancer (PCa), as well as high-grade prostatic intraepithelial neoplasia (HGPIN), in prostatic needle biopsy specimens. Tissues from 4526 men, who underwent systematic ultrasound-guided sextant needle biopsies of the prostate, were classified in the following order as PCa, or HGPIN, or chronic inflammation or benign. PCa was diagnosed in 1633 (36.1%), HGPIN in 535 (11.8%) and chronic inflammation in 347 (7.7%). Chronic inflammation conferred a protective effect from PCa: odds ratio (OR) = 0.20, 95% confidence interval (CI) = 0.15-0.28. Chronic inflammation was also inversely associated with HGPIN: OR = 0.11, 95% CI = 0.05-0.22. The ORs remained virtually unchanged after adjustment for age, serum prostate-specific antigen (PSA), digital rectal examination (DRE) and gland volume. Chronic inflammation is more frequent in the presence of benign histology than it is in the presence of PCa or HGPIN.

The development of prostate cancer despite late onset androgen deficiency

Androgen withdrawal causes the regression of prostate cancer and is used in therapy, but the role of androgens in the development of prostate cancer is uncertain. We present a case of prostate cancer diagnosed in a man who had been clinically androgen deficient for some years. This case and reviewed literature suggest that while early androgen exposure may be important in the prostatic carcinogenesis, late onset androgen deficiency is not protective. Thus, hypogonadal men considering androgen replacement therapy need to be adequately counseled, screened for prostate cancer and followed closely during treatment.

Prostatic stromal microenvironment and experimental diabetes

The diabetes causes alterations in various organ systems, including the male accessory sex glands. The prostate is very important in the reproductive process and it is a frequent target of malignant changes. The aim of this work was to demonstrate the histochemical and ultrastructural alterations in the prostate of diabetic animals. Two groups of animals were utilized: control and non-obese diabetic mice (NOD). Twelve days after the characterization of diabetic status the ventral prostate was collected, fixed in Karnovsky and paraformaldehyde, processed for histochemistry and TEM associated to stereology. The results showed reduction of the epithelial area and increasing of the stromal area with muscular and collagen hypertrophy in the prostatic gland. It was characterized the development of prostatic intraepithelial neoplasia, inflammatory processes and dilation of the organelles involved in the secretory process. It was concluded that diabetes besides damaging the reproductive process, affects the glandular homeostasis favoring the development of prostatic pathologies.

TGF-beta signaling in fibroblasts modulates the oncogenic potential of adjacent epithelia

Stromal cells can have a significant impact on the carcinogenic process in adjacent epithelia. The role of transforming growth factor-beta (TGF-beta) signaling in such epithelial-mesenchymal interactions was determined by conditional inactivation of the TGF-beta type II receptor gene in mouse fibroblasts (Tgfbr2fspKO). The loss of TGF-beta responsiveness in fibroblasts resulted in intraepithelial neoplasia in prostate and invasive squamous cell carcinoma of the forestomach, both associated with an increased abundance of stromal cells. Activation of paracrine hepatocyte growth factor (HGF) signaling was identified as one possible mechanism for stimulation of epithelial proliferation. Thus, TGF-beta signaling in fibroblasts modulates the growth and oncogenic potential of adjacent epithelia in selected tissues.

Prostate intraepithelial neoplasia induced by prostate restricted Akt activation: the MPAKT model

To determine whether Akt activation was sufficient for the transformation of normal prostate epithelial cells, murine prostate restricted Akt kinase activity was generated in transgenic mice (MPAKT mice). Akt expression led to p70S6K activation, prostatic intraepithelial neoplasia (PIN), and bladder obstruction. mRNA expression profiles from MPAKT ventral prostate revealed similarities to human cancer and an angiogenic signature that included three angiogenin family members, one of which was found elevated in the plasma of men with prostate cancer. Thus, the MPAKT model may be useful in studying the role of Akt in prostate epithelial cell transformation and in the discovery of molecular markers relevant to human disease.

Haploinsufficiency at the Nkx3.1 locus. A paradigm for stochastic, dosage-sensitive gene regulation during tumor initiation

Tumorigenesis requires sequential accumulation of multiple genetic lesions. In the prostate, tumor initiation is often linked to loss of heterozygosity at the Nkx3.1 locus. In mice, loss of even one Nkx3.1 allele causes prostatic epithelial hyperplasia and eventual prostatic intraepithelial neoplasia (PIN) formation. Here we demonstrate that Nkx3.1 allelic loss extends the proliferative stage of regenerating luminal cells, leading to epithelial hyperplasia. Microarray analysis identified Nkx3.1 target genes, many of which show exquisite dosage sensitivity. The number of Nkx3.1 alleles determines the relative probabilities of stochastic activation or inactivation of a given target gene. Thus, loss of a single Nkx3.1 allele likely results in hyperplasia and PIN by increasing the probability of completely inactivating select Nkx3.1-regulated pathways within a subset of affected cells.

Conditional loss of Nkx3.1 in adult mice induces prostatic intraepithelial neoplasia

The homeodomain-containing transcription factor NKX3.1 is a putative prostate tumor suppressor that is expressed in a largely prostate-specific and androgen-regulated manner. Loss of NKX3.1 protein expression is common in human prostate carcinomas and prostatic intraepithelial neoplasia (PIN) lesions and correlates with tumor progression. Disruption of the murine Nkx3.1 gene results in defects in prostate branching morphogenesis, secretions, and growth. To more closely mimic the pattern of NKX3.1 loss that occurs in human prostate tumors, we have used Cre- and loxP-mediated recombination to delete the Nkx3.1 gene in the prostates of adult transgenic mice. Conditional deletion of one or both alleles of Nkx3.1 leads to the development of preinvasive lesions that resemble PIN. The pattern of expression of several biomarkers (Ki-67, E-cadherin, and high-molecular-weight cytokeratins) in these PIN lesions resembled that observed in human cases of PIN. Furthermore, PIN foci in mice with conditional deletion of a single Nkx3.1 allele lose expression of the wild-type allele. Our results support the role of NKX3.1 as a prostate tumor suppressor and indicate a role for this gene in tumor initiation.

New concepts in the pathology of prostatic epithelial carcinogenesis

The development of drugs to prevent prostate cancer is underway, yet monitoring the potential efficacy of these agents during clinical trials relies on measuring intermediate endpoints. In this review, various candidate markers are presented that are under different stages of evaluation as intermediate endpoint biomarkers. In addition, the near future will bring an unprecedented wave of new potential biomarkers. For instance, through genomics-based methods many new genes are being discovered whose altered expression may be involved in different phases of prostate cancer development and progression. In the development of rational approaches for selecting which of these untested biomarkers may be useful to measure systematically, there must be an improved understanding of the mechanisms of prostatic carcinogenesis. We submit that this improved understanding will come through new knowledge of the biology of normal prostate epithelial cells, the determination of the precise target cells of transformation, and how their growth regulation is genetically and epigenetically perturbed during the phases of initiation and progression. In this review, therefore, we also present our recent immune-mediated oxidant injury and regeneration hypothesis of why and how the prostate is targeted for carcinogenesis.

Prevention of prostate cancer

Prostate cancer lends itself ideally to chemoprevention due to a number of specific features of the disease. These include a high prevalence, long latency time, hormone dependency, the availability of an ideal marker (prostate serum antigen) and, last but not least, the availability of a defined precursor lesion (prostatic intraepithelial neoplasia) among the pathways leading to clinical disease. The large variability in the incidence of the tumor in different geographical regions suggests the possibility of nutritional influences regarding the stimulation and/or inhibition of clinical cancer, as there is a similar prevalence worldwide of the precursor lesion. A great number of publications have dealt with a number of nutritional factors, including fat, phytoestrogens, vitamins (especially vitamin E) and minerals such as selenium and calcium. These are among the most reported substances with a possible influence on disease development; however, unfortunately there are no conclusive results or study outcomes at present which satisfy accepted standards of evidence. Ongoing studies on nutrition and prostate cancer may bring the required evidence to support what is still only an hypothesis at present.

Correlation of increased apoptosis and proliferation with development of prostatic intraepithelial neoplasia (PIN) in ventral prostate of the Noble rat

BACKGROUND

Imbalance between cell proliferation and cell apoptosis has been considered a key factor in carcinogenesis. Prostatic intraepithelial neoplasia (PIN) is the most likely precancereous lesion and represents the major target for chemoprevention of prostate cancer. The proliferative and apoptotic activities involved in the development of PIN remain to be elucidated.

METHODS

Ventral prostates were removed from Noble rats that were treated with a combination of testosterone (T) and estradiol (E(2)) for certain periods of time, and processed for histopathological grading. To evaluate the relationship between cell proliferation and apoptosis, immunohistochemistry for proliferating cell nuclear antigen (PCNA), Ki-67, and in situ DNA nick labeling (TUNEL) for identifying apoptotic cells, were performed on paraffin sections from prostate samples with PIN lesions. The results were correlated with expression patterns of Bcl-2 and Bax, two proteins related to cell survival and cell apoptosis.

RESULTS

Pathologically, low-grade PIN (LGPIN) and high-grade PIN (HGPIN) were observed in ducts or alveoli after 3 and 5 months of T + E(2) treatment, respectively. Quantitative evaluation of Ki-67 showed an increased proliferative activity in HGPIN. In contrast to normal prostatic ducts and alveoli, which showed no positive staining for Ki-67 in the nuclei of luminal cells, 25% Ki-67-positive cells were detected in luminal cells of HGPIN. Only 7.5% Ki-67-positive cells were found belonging to the basal cell type. The Ki-67 index showed a higher growth rate from normal to HGPIN. The PCNA results showed a similar expression pattern to that of Ki-67 in normal prostate, LGPIN, and HGPIN. Apoptotic index (number of apoptotic cells/total number of cell counted) was significantly higher (P = 0.028) in HGPIN (3.23%) than in control prostate (1.19%). In contrast to control prostate, which showed no definite expression of Bcl-2, an intense positive expression of Bcl-2 in HGPIN was observed. Positive expression of Bax protein was observed in glandular epithelial cells of normal control prostate and HGPIN as well.

CONCLUSIONS

Overexpression of Bcl-2 and higher Ki-67 or PCNA indices in HGPIN suggest that abnormal growth of premalignant lesions might result from an increase in cell proliferation. An increased apoptotic rate in HGPIN further implicates that active apoptosis may accelerate cell turnover in the development of premalignant lesions of the prostate.

Extent and zonal distribution of prostatic intraepithelial neoplasia in patients with prostatic carcinoma in Japan: analysis of whole-mounted prostatectomy specimens

BACKGROUND

Prostatic intraepithelial neoplasia (PIN), an intraluminar proliferation of epithelial cells in ducts and acini, is divided into high-grade (HGPIN) and low-grade (LGPIN), based on morphologies. HGPIN is considered to be a putative precursor of prostatic adenocarcinoma (PCA). Information on PIN has been limited in Japan, because PIN had not been regarded as a precursor lesion for PCA.

METHODS

In this study, extent and zonal distribution of PIN together with its relationship with PCA were examined in totally embedded radical prostatectomy specimens obtained from 70 patients with PCA. Fifty-three patients received androgen deprivation therapy (castrated) and remaining 17 did not (noncastrated).

RESULTS

Frequency of HGPIN in noncastrated cases (76%) was much higher than that in castrated cases (26%) (P < 0.001). LGPIN showed the same tendency, but the difference was smaller. Difference in mean number of HGPIN in noncastrated and castrated cases (12.0 and 6.4, respectively) was more marked than in LGPIN (6.4 and 5.1, respectively). Reduction rate of mean size in HGPIN (26%) by the androgen deprivation therapy was larger than in LGPIN. When evaluated in noncastrated cases, the coexistence of PCA and HGPIN was found in 76% of cases in the nontransition and 53% in the transition zone. Close association of PCA and PIN (</=2 mm distance between lesions) was more frequently found in HGPIN (55% of lesions) than in LGPIN (37%) (P < 0.05). Frequency of close association of HGPIN with PCA was 65% in the nontransition and 35% in transition zone.

CONCLUSIONS

The present study from Japan supports the etiological importance of HGPIN in the development of PCA. The effect of androgen deprivation therapy is much more marked in HGPIN than in LGPIN.

Changes in the normal-looking epithelium in prostates with PIN or cancer

BACKGROUND

In prostatic neoplasia, the time from tumour initiation and progression to invasive carcinoma often begins in men in the fourth and fifth decades of life and extends across decades. Until recently, the events initiating the process and the developments concomitant with the evolution towards invasive disease were largely unknown.

METHODS

Quantitative and analytical methods are applied to provide insights into certain individual molecular events and their effects on the complex multiple feedback system of cellular metabolism and regulation in prostate neoplasia.

RESULTS

Prostatic intraepithelial neoplasia (PIN) and prostate cancer (PCa) are associated with or possibly preceded by changes in the chromatin of secretory cell nuclei. The changes are detectable with a Bayesian belief network and quantifiable by computer image analysis in prostatic tissue that still appears histologically normal. In addition, normal looking prostate epithelium shows some molecular changes similar to those present in the associated preneoplastic and neoplastic lesions. Such changes are also occasionally present in normal prostate glands without PIN and cancer.

CONCLUSIONS

The subtle morphological and molecular changes of normal looking epithelium might be seen as the onset of the development of prostatic neoplasia.

Progression of prostatic intraepithelial neoplasia to invasive carcinoma in C3(1)/SV40 large T antigen transgenic mice: histopathological and molecular biological alterations

The progression of prostatic intraepithelial neoplasia (PIN) to invasive prostate carcinoma has been analyzed in the C3(1)/T(AG) transgenic mouse model and appears very similar to the process proposed to occur in humans. PIN lesions in these transgenic mice histologically resemble those found in human PIN. Low-grade PIN was observed in the ventral and dorsolateral lobes at 2 months of age, whereas high-grade PIN was found in both lobes by 5 months of age. A progressive increase in the number of PIN lesions was observed with age. Prostate carcinomas, which appeared to arise from PIN lesions, were found by 7 months of age in the ventral lobe and 11 months of age in the dorsolateral lobe. Expression of T(AG) mRNA and protein in these lesions correlated with the development of PIN and carcinomas, as did the overexpression of p53 protein. Apoptosis levels were quite low in normal epithelial cells, moderate in low-grade PIN, and high in high-grade PIN and carcinomas. Levels of expression of proliferating cell nuclear antigen correlated with the degree of severity of the prostate lesions. Eighteen % of PIN lesions were found to already harbor Ha-ras mutations, whereas 33% of carcinomas showed various mutations in Ha-ras, Ki-ras, and/or p53. Mutations in Ha-ras may, therefore, be an early event in a significant portion of PIN lesions. Because high-grade PIN showed many characteristics similar to those observed in carcinomas and high-grade PIN was often found contiguous to carcinomas, we conclude that high-grade PIN is a precursor lesion of prostate carcinoma in this transgenic model. These transgenic mice will be useful to study mechanisms responsible for the progression of invasive carcinomas from PIN precursor lesions, as may occur during the development of prostate cancer in humans.

A unifying hypothesis that links benign prostatic hyperplasia and prostatic intraepithelial neoplasia with prostate cancer. Invited comments

Prostatic Intraepithelial Neoplasia (PIN) and prostatic cancer (PCA) are not caused by infection, allergic reaction, inadequate immunological response, ischemia, ageing, systemic hormones, carcinogens, nor prostatic ductal contents. PIN and PCA are apparently caused by increased inner acinar pressure due to partially blocked draining ducts. Only this explanation can account for all the observations about PIN and PCA. All other possible causes are disproved by specific observations. In order to further clarify the cause of PIN and PCA, it is important to discover if peripheral zone lesions cluster around ducts or blood vessels. PIN patterns are the morphological precursors of both PCA and prostatic cysts. Different PIN patterns represent different adaptive stages to increasing inner acinar pressure. The immediate tissue cause of PCA is PIN disruption seeding the stroma with high-grade PIN (HGPIN) cells. These cells, programmed for adaptive proliferation and mobility in PIN, are sufficient in the stroma to cause all stages and patterns of invasive PCA. No mutated cells are necessary. For reasons given, the primary cause of the initial ductal blockage that results in PIN and PCA cannot be inflammation, stones, proteineous plugs, infarction, venus thrombosis, ductal hyperplasia, nor a constricted penis at ejaculation. Only benign prostatic hyperplasia (BPH) can explain all the facts and is thus the primary cause of the ductal blockage resulting in cysts, PIN and PCA. The main causes of BPH are apparently disuse atrophy of sexual and abdominal muscles, and atherosclerosis of the capsular branch of the prostatic artery, causes atypical adenomatous hyperplasia (AAH) in the transition zone. The resulting muscular and glandular atrophy decreases local and general growth inhibitors. New growth in the adult prostate is abnormal because epithelial cells grow into ducts rather into the stroma. In such ducts, the growths cannot receive stromal growth inhibitory signals, and thus continue to grow indefinitely and result in BPH, AAH-adenosis, blockage of ducts, cysts, PIN and PCA.