Prostate Development and Carcinogenesis

Production aspects of testosterone by microbial biotransformation and future prospects

In human males, TS plays a key role in maintaining health and sexual functioning. Cholesterol acts as a precursor molecule for its biosynthesis. The microbial biotransformation of cholesterol by numerous microbes like bacteria, fungi, yeasts, etc. has led to the synthesis of TS out of human body making it a great example for industrial steroid production due to its therapeutic properties. Biotransformation through microbes is more advantageous over chemical synthesis as it gives higher conversion rates, higher specificity; reaction goes under mild conditions like temperature and neutral pH, thus being an effective alternate to chemical route. Current review focuses on production aspects of TS by microbial biotransformation and its future prospects with recent advancement.

Novel In Vivo model for combinatorial fluorescence labeling in mouse prostate

BACKGROUND

The epithelial layer of prostate glands contains several types of cells, including luminal and basal cells. Yet there is paucity of animal models to study the cellular origin of normal or neoplastic development in the prostate to facilitate the treatment of heterogenous prostate diseases by targeting individual cell lineages.

METHODS

We developed a mouse model that expresses different types of fluorescent proteins (XFPs) specifically in prostatic cells. Using an in vivo stochastic fluorescent protein combinatorial strategy, XFP signals were expressed specifically in prostate of Protein Kinase D1 (PKD1) knock-out, K-Ras(G) (12) (D) knock-in, and Phosphatase and tensin homolog (PTEN) and PKD1 double knock-out mice under the control of PB-Cre promoter.

RESULTS

In vivo XFP signals were observed in prostate of PKD1 knock-out, K-Ras(G) (12) (D) knock-in, and PTEN PKD1 double knock-out mice, which developed normal, hyperplastic, and neoplastic prostate, respectively. The patchy expression pattern of XFPs in neoplasia tissue indicated the clonal origin of cancer cells in the prostate.

CONCLUSIONS

The transgenic mouse models demonstrate combinatorial fluorescent protein expression in normal and cancerous prostatic tissues. This novel prostate-specific fluorescent labeled mouse model, which we named Prorainbow, could be useful in studying benign and malignant pathology of prostate.

Chronic exposure to arsenic, estrogen, and their combination causes increased growth and transformation in human prostate epithelial cells potentially by hypermethylation-mediated silencing of MLH1

BACKGROUND

Chronic exposure to arsenic and estrogen is associated with risk of prostate cancer, but their mechanism is not fully understood. Additionally, the carcinogenic effects of their co-exposure are not known. Therefore, the objective of this study was to evaluate the effects of chronic exposure to arsenic, estrogen, and their combination, on cell growth and transformation, and identify the mechanism behind these effects.

METHODS

RWPE-1 human prostate epithelial cells were chronically exposed to arsenic and estrogen alone and in combination. Cell growth was measured by cell count and cell cycle, whereas cell transformation was evaluated by colony formation assay. Gene expression was measured by quantitative real-time PCR and confirmed at protein level by Western blot analysis. MLH1 promoter methylation was determined by pyrosequencing method.

RESULTS

Exposure to arsenic, estrogen, and their combinations increases cell growth and transformation in RWPE-1 cells. Increased expression of Cyclin D1 and Bcl2, whereas decreased expression of mismatch repair genes MSH4, MSH6, and MLH1 was also observed. Hypermethylation of MLH1 promoter further suggested the epigenetic inactivation of MLH1 expression in arsenic and estrogen treated cells. Arsenic and estrogen combination caused greater changes than their individual treatments.

CONCLUSIONS

Findings of this study for the first time suggest that arsenic and estrogen exposures cause increased cell growth and survival potentially through epigenetic inactivation of MLH1 resulting in decreased MLH1-mediated apoptotic response, and consequently increased cellular transformation.

Role of stromal-epithelial interaction in the formation and development of cancer cells

Identification of gene expression mechanisms began with works on embryonic induction. The same mechanism of cell-cell interactions also contributes to the process of oncogenesis. Damage to epithelial cells' genetic apparatus turns them into precancerous stem cells that are not yet capable of tumor growth. They can be transformed into cancer stem cells and undergo further progression as a result of epigenetic effects of apocrine secretion by surrounding activated stromal cells (mostly myofibroblasts). These factors may activate the damaged genetic information. On the contrary, the level of malignancy can be decreased by adding culture medium from non-activated stromal cells. One must not exclude the possibility that in a number of cases genetically altered bone marrow may migrate to damaged or inflamed tissues and become there a source of stromal cells, as well as of parenchymal stem cells in a damaged organ, where they may give rise to changed epithelial (precancerous) stem cells or to activated stromal cells, thus leading to malignant tumor growth. Cancer treatment should also affect activated stromal cells. It may prevent emergence and progression of cancerous stem cells.

Expression of proton-coupled oligopeptide transporter (POTs) in prostate of mice and patients with benign prostatic hyperplasia (BPH) and prostate cancer (PCa)

BACKGROUND

Proton-coupled oligopeptide transporters (POTs) serve as integral membrane protein for the cellular uptake of di/tripeptide. Prostate has a large requirement of nutriment for its function to produce and secrete prostatic fluid. Besides, prostate suffered from limited therapy effect of drug treatment. Thus present study was performed to evaluate the expression of POTs in prostate of mice and human with the aim to provide information for potential role of POTs in absorption of nutriment and peptidomimetic drugs in prostate.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot methods were applied to study the mRNA, protein expression of POTs in prostate, human prostate cancer cells (PC-3), and human prostate epithelial cells (RWPE-1).

RESULTS

qRT-PCR study showed different characteristic of POTs mRNA expression in mouse prostate. Among these transporters, protein expression of PepT2 was detected and increasing during the development of mouse prostate, while PepT1, PHT1, and PHT2 protein was not detected. Furthermore, different characteristic of regulation by inflammation on POTs mRNA expression was found in RWPE-1 and PC-3. In addition, mRNA expression of PepT2 and PHT1 in prostate of patients with PCa was demonstrated be lower compared with BPH.

CONCLUSIONS

These findings provide the first evidence for the expression of POTs in prostate of mice and patients with BPH or PCa and suggest that POTs are likely to play a role in the transport of di/tripeptides and peptidomimetics in prostate.

Effects of chronic exposure to arsenic and estrogen on epigenetic regulatory genes expression and epigenetic code in human prostate epithelial cells

Chronic exposures to arsenic and estrogen are known risk factors for prostate cancer. Though the evidence suggests that exposure to arsenic or estrogens can disrupt normal DNA methylation patterns and histone modifications, the mechanisms by which these chemicals induce epigenetic changes are not fully understood. Moreover, the epigenetic effects of co-exposure to these two chemicals are not known. Therefore, the objective of this study was to evaluate the effects of chronic exposure to arsenic and estrogen, both alone and in combination, on the expression of epigenetic regulatory genes, their consequences on DNA methylation, and histone modifications. Human prostate epithelial cells, RWPE-1, chronically exposed to arsenic and estrogen alone and in combination were used for analysis of epigenetic regulatory genes expression, global DNA methylation changes, and histone modifications at protein level. The result of this study revealed that exposure to arsenic, estrogen, and their combination alters the expression of epigenetic regulatory genes and changes global DNA methylation and histone modification patterns in RWPE-1 cells. These changes were significantly greater in arsenic and estrogen combination treated group than individually treated group. The findings of this study will help explain the epigenetic mechanism of arsenic- and/or estrogen-induced prostate carcinogenesis.

Cancer Tissue Engineering: A Novel 3D Polystyrene Scaffold for In Vitro Isolation and Amplification of Lymphoma Cancer Cells from Heterogeneous Cell Mixtures

Isolation and amplification of primary lymphoma cells in vitro setting is technically and biologically challenging task. To optimize culture environment and mimic in vivo conditions, lymphoma cell lines were used as a test case and were grown in 3-dimension (3D) using a novel 3D tissue culture polystyrene scaffold with neonatal stromal cells to represent a lymphoma microenvironment. In this model, the cell proliferation was enhanced more than 200-fold or 20,000% neoplastic surplus in 7 days when less than 1% lymphoma cells were cocultured with 100-fold excess of neonatal stroma cells, representing 3.2-fold higher proliferative rate than 2D coculture model. The lymphoma cells grew and aggregated to form clusters during 3D coculture and did not maintained the parental phenotype to grow in single-cell suspension. The cluster size was over 5-fold bigger in the 3D coculture by day 4 than 2D coculture system and contained less than 0.00001% of neonatal fibroblast trace. This preliminary data indicate that novel 3D scaffold geometry and coculturing environment can be customized to amplify primary cancer cells from blood or tissues related to hematological cancer and subsequently used for personalized drug screening procedures.

Biochemical polymorphism of the growth hormone system proteins and its manifestations in human prostate cells

The basic mechanisms are considered that are responsible for producing biochemical polymorphism of human proteins realized at three basic levels: the structures of genome and genes; the transcription and maturation of transcripts; the postsynthetic formation of functionally active protein products of gene expression. The data on biochemical polymorphism of growth hormone (GH) and some other proteins that are directly or indirectly necessary for its functioning and support this polymorphism by polylocus, polyallelism, alternative splicing, and various postsynthetic modifications are analyzed. The role of polymorphic proteins of the GH system is discussed in formation of a variety of oligomeric molecular structures of this system (multicomponent transport complexes, receptors, and endocellular protein ensembles involved in the regulation of gene expression). It is emphasized that such structural polymorphism significantly influences the biological effects in various parts of the GH system during physiological processes and in tumors, in particular in prostate cancer.

Local insulin-like growth factor-I of ventral prostate was upregulated during long-term castration and may function through the autocrine system

The insulin-like growth factor I (IGF-I) is one of the main mitogens and anti-apoptotic factors, which has an important role in cell proliferation, inhibiting cell death in prostate cancer (PCa), and may act as a replacement for androgen after castration. Characterizing the changes in local IGF-I levels in the prostate after castration, is therefore of great importance for doctors to guide and select therapy models after surgical castration in men with PCa. The present study was performed to detect IGF-I of local ventral prostate (VP) at intervals up to 24 weeks after castration by a combination of reverse transcriptase PCR, western-blot, immunohistochemistry and immunofluorescence. We found IGF-I to be decreased sharply after castration and that mRNA and protein levels reached their minimum at 2 days and 5 days, respectively. The level of IGF-I increased gradually and although mRNA levels remained high for longer than 2 weeks, protein levels remained high for longer than 4 weeks. The epithelium cells of VP express IGF-I and its receptor longer than 2 weeks after castration. These findings suggested that although IGF-I of local VP decreases sharply in short-stage castration, its levels increase gradually and remain at high levels at least until 24 weeks. IGF-I synthesized mainly from epithelial cells, which may function through the autocrine system longer than 2 weeks castration.

Intensity of stromal changes predicts biochemical recurrence-free survival in prostatic carcinoma

OBJECTIVE

The reactive stroma of prostate cancer contains a mixture of myofibroblasts and fibroblasts, while fully differentiated smooth-muscle cells are very rare or absent. In experimental prostate cancer models, prostatic stromal cells promote angiogenesis and stimulate prostate tumorigenesis. The aim of this study is to analyse whether the intensity of stromal changes can predict survival in patients with prostatic carcinoma.

MATERIAL AND METHODS

Stromal reaction was quantified histochemically and imunohistochemically in 50 patients treated with radical prostatectomy for clinically localized prostate carcinoma and its relationship with established prognostic factors was assessed.

RESULTS

Kaplan-Meier analysis showed a significant association between the pattern of vimentin and desmin expression and the length of disease-free period; patients with a higher vimentin or lower desmin expression had a shorter disease-free period. On multivariate analysis only vimentin expression (odds ratio 4.06, 95% confidence interval 1.01-16.26, p = 0.049) was a significant predictor of biochemical recurrence. In patients with identical Gleason pattern and Gleason score the level of vimentin expression could identify patients with a higher risk of disease recurrence.

CONCLUSIONS

Intensity of stromal changes could serve as an independent prognostic factor in the assessment of biochemical recurrence-free survival. Among prostate cancer patients with an identical Gleason score, it could identify patients with a higher risk of biochemical recurrence. Thus, stromal changes and their intensity could serve as a novel marker for the recognition of patients with an increased risk of disease recurrence.

Modification of progesterone and testosterone by a food-borne thermophile Geobacillus kaustophilus

The present work was carried out to study structural modification of steroids by Geobacillus kaustophilus, a bacterial thermophile present in milk and the environment. Incubation of progesterone and testosterone with G. kaustophilus at 65 degrees C resulted in oxygenated steroid nuclei. The oxygenation of the steroid molecule was stereo specific. Seven metabolites of progesterone horizontal line 6beta/6alpha-hydroxytestosterone, 20-hydroxyprogesterone, 6beta-/6alpha-20-dihydroxyprogesterone, 5alpha-pregnane-3,6,20-trione, and 3beta-hydroxy-5alpha-pregnane-6,20-dione horizontal line were identified. Four compounds horizontal line namely, 66-/6--hydroxytestosterone and 6beta/6alpha-hydroxyandrostenedione horizontal line and androst-4-en-3,17-dione were identified as testosterone metabolites. This shows that G. kaustophilus is capable of modifying steroid nuclei at elevated temperatures. G. kaustophilus is a stable thermophile first isolated from milk. Our results show that endogenous steroids present in milk can be modified by G. kaustophilus, causing detrimental effect on human health.

Gene targeting to the stroma of the prostate and bone

Stromal-epithelial interactions mediated by paracrine signaling mechanisms dictate prostate development and progression of prostate cancer. The regulatory role of androgens in both the prostate stromal and epithelial compartments set the prostate apart from many other organs and tissues with regard to gene targeting. The identification of androgen-dependent prostate epithelial promoters has allowed successful gene targeting to the prostate epithelial compartment. Currently, there are no transgenic mouse models available to specifically alter gene expression within the prostate stromal compartment. As a primary metastatic site for prostate cancer is bone, the functional dissection of the bone stromal compartment is important for understanding stromal-epithelial interactions associated with metastatic tumor growth. Use of currently available methodologies for the expression or deletion of gene expression in recent research studies has advanced our understanding of the stroma. However, the complexity of stromal heterogeneity within the prostate remains a challenge to obtaining compartment or cell-lineage-specific in vivo models necessary for furthering our understanding of prostatic developmental, benign, tumorigenic, and metastatic growth.

Sonic and desert hedgehog signaling in human fetal prostate development

BACKGROUND

Hedgehog signaling is thought to play an important role in rodent prostate organogenesis and morphogenesis. However, the role of this signaling pathway in human fetal prostate development has not been investigated.

METHODS

Twenty-five human fetal prostates at various developmental stages (10-39 weeks) were included. Fifteen specimens were processed for H&E and immunohistochemical staining of the Hedgehog signaling components: Sonic Hedgehog (SHH), Desert Hedgehog (DHH), Patched-1(PTC1), Patched-2 (PTC2), Smoothened (SMO), GLI1, and proliferating cell nuclear antigen (PCNA). SHH, DHH, and GLI1 expression was also analyzed in ten snap-frozen specimens by Western blot.

RESULTS

SHH, DHH, SMO, PTC1, GLI1, and PCNA expression, assessed by a semi-quantitative immunohistochemical method, was found mainly in the developing prostatic epithelial ducts, beginning at 10 weeks and peaking at 16 and 28 weeks with a dip occurring at 20 weeks, with the exception of PTC2.

CONCLUSION

Both SHH and DHH signaling components were detected during human fetal prostate development. Despite the high expression of PTC2 in the epithelium as well as the stroma in the early time of development, the expression of SHH, DHH, SMO, PTC1, and a SHH/DHH target transcription factor, GLI-1, were all largely restricted to epithelium in the developing prostate, suggesting that SHH/DHH signaling is primarily through an autocrine mechanism in human fetal prostate organogenesis.

Growth curves of the fetal prostate based on three-dimensional reconstructions: a correlation with gestational age and maternal testosterone levels

OBJECTIVE

To create a nomogram of the fetal growth of the human prostate corresponding to gestational age, and to investigate the relationship between the expansive growth of the fetal prostate and the maternal testosterone surge during pregnancy.

MATERIALS AND METHODS

In all, 27 fetal prostates at 11-40 weeks of gestation, and seven neonatal specimens at 1-20 weeks after birth, were analysed. Serial sections of prostates were immunostained and examined using light microscopy. After modular image acquisition the volumes were calculated using three-dimensional reconstruction. The prostate volumes were correlated with gestational age, and related to reference testosterone levels during pregnancy.

RESULTS

There was exponential growth of the fetal prostate with gestational age. The increasing volume of the prostate during the fetal period corresponded with maternal testosterone levels. In the second trimester there was a significant increase in prostate volume in relation to the bladder. In infants, macroscopically there was an inverse proportion between bladder size and prostate volume.

CONCLUSIONS

Starting from the second trimester there is distinct growth of the fetal prostate, obviously triggered by the maternal testosterone surge. In neonates there is an inversion of the dimensions between bladder and prostate. These results indicating exponential growth of the fetal prostate provide evidence of a gender-related transient infravesical obstruction in human fetuses.

Castration rapidly decreases local insulin-like growth factor-1 levels and inhibits its effects in the ventral prostate in mice

BACKGROUND

The mechanisms by which castration induces prostate involution are largely unknown.

METHODS

Early responses to castration in mouse ventral prostate (VP) were explored by quantitative microscopy, cDNA array expression, quantitative RT-PCR, and Western blot analysis. As several changes occurred in the insulin-like growth factor (IGF) system this was studied in more detail. Laser micro-dissection was used to localize sites of IGF-1 and IGF-1 receptor (IGF-R1) production. IGF-1 protein levels and IGF-R1 mediated signaling via insulin regulated substrate 1 and 2 (IRS-1 and 2) were examined. IGF-1 was injected into the VP in intact, and castrated mice and effects studied 1 day later.

RESULTS

IGF-1 and IGF binding protein 2 (IGFBP-2) mRNA were rapidly reduced whereas IGFBP-3 and IGF-R1 mRNA were increased after castration. IGF-1 was principally produced in the stromal compartment, while IGF-R1 was produced in both epithelial and stromal cells. IGF-1 and IRS-1 protein levels were decreased 1 and 3 days after castration, respectively, while IRS-2 was unchanged. Inactivating phosphorylation of IRS-1 at serine 307 was increased 1 day after castration, and activating phosphorylation at tyrosine 612 was decreased 2 days later. These changes were accompanied by decreased cell proliferation and increased cell death in the glandular and vascular compartment. Local injection of IGF-1 increased vascular density and epithelial cell proliferation in intact mice, but had no effect in castrated animals.

CONCLUSION

Decreased IGF-1 levels and action may mediate some of the key features of castration-induced prostate involution.

Insulin-Like Growth Factor (IGF) family and prostate cancer

There is abundant in vitro, animal and epidemiologic evidence to suggest that the Insulin-Like Growth Factor (IGF) family is a multi-component network of molecules which is involved in the regulation of both physiological and pathological growth processes in prostate. The IGF family plays a key role in cellular metabolism, differentiation, proliferation, transformation and apoptosis, during normal development and malignant growth. This family also seem essential in prostate cancer bone metastases, angiogenesis and androgen-independent progression. Therapeutic alternatives in men with progressive prostate cancer after androgen ablation are very limited. More effective therapies are needed for these patients. Pharmacologic interventions targeting the IGF family are being devised. Such strategies include reduction of IGF-I levels (growth hormone-releasing hormone antagonists, somatostatin analogs), reduction of functional IGF-I receptor levels (antisense oligonucleotides, small interfering RNA), inhibition of IGF-IR and its signalling (monoclonal antibodies, small-molecule tyrosine kinase inhibitors) and Insulin-Like Growth Factor Binding Proteins.

Metabolic characterization of human prostate cancer with tissue magnetic resonance spectroscopy

Diagnostic advancements for prostate cancer have so greatly increased early detections that hope abounds for improved patient outcomes. However, histopathology, which guides treatment, often subcategorizes aggressiveness insufficiently among moderately differentiated Gleason score (6 and 7) tumors (>70% of new cases). Here, we test the diagnostic capability of prostate metabolite profiles measured with intact tissue magnetic resonance spectroscopy and the sensitivity of local prostate metabolites in predicting prostate cancer status. Prostate tissue samples (n = 199) obtained from 82 prostate cancer patients after prostatectomy were analyzed with high-resolution magic angle spinning proton magnetic resonance spectroscopy, and afterwards with quantitative pathology. Metabolite profiles obtained from principal component analysis of magnetic resonance spectroscopy were correlated with pathologic quantitative findings by using linear regression analysis and evaluated against patient pathologic statuses by using ANOVA. Paired t tests show that tissue metabolite profiles can differentiate malignant from benign samples obtained from the same patient (P < 0.005) and correlate with patient serum prostate-specific antigen levels (P < 0.006). Furthermore, metabolite profiles obtained from histologically benign tissue samples of Gleason score 6 and 7 prostates can delineate a subset of less aggressive tumors (P < 0.008) and predict tumor perineural invasion within the subset (P < 0.03). These results indicate that magnetic resonance spectroscopy metabolite profiles of biopsy tissues may help direct treatment plans by assessing prostate cancer pathologic stage and aggressiveness, which at present can be histopathologically determined only after prostatectomy.