Biopsy of the mouse prostate

Quantitative morphological analysis of age structural changes in prostate of experimental animals with ethanol poisoning

OBJECTIVE

Aim: To find out the age remodeling of the structural components of the prostate gland at alcohol poisoning using quantitative morphological analysis.

PATIENTS AND METHODS

Materials and Methods: The structure of the prostate gland of 4 white male rats groups were morphologically investigated. The 1 group included 30 control intact animals aged 8 months, the 2-nd group - 30 rats aged 24 months, the 3-rd group - 30 8-month-old animals with ethanol intoxication, and the 4-th group included 30 24-month-old rats with the specified simulated pathology. Ethanol intoxication was modeled by intragastric administration of 30% ethyl alcohol solution at a dose of 20 ml/kg once daily for 28 days. Rats were euthanized by bloodletting under general thiopental anesthesia 28 days after the beginning of the experiment. The area of glands, the height of glandular epithelial cells, the area of their nuclei and cytoplasm, the nuclear-cytoplasmic ratio in these cells and the stromal-parenchymal ratio in the organ were studied using light microscopy and were determined morphometrically. Morphometric parameters were processed statistically.

RESULTS

Results: It was established that with age in the intact prostate of laboratory sexually mature white male rats, the area of glands, the height of glandular epitheliocytes, the area of their nuclei and cytoplasm, with the stability of nuclear-cytoplasmic ratios in the epithelial cells of the glands, significantly decreases, and the stromal-parenchymal ratio in the organ under study increases. Long-term ethanol poisoning leads to pronounced structural changes in the prostate, which is characterized by pronounced atrophy of the glandular epithelium, a decrease in the area of the glands, a decrease in the height of epithelial cells, a violation of nuclear-cytoplasmic relations in them, an increase in stromal-parenchymal ratio, and a prominent growth of the muscle-elastic stroma. The revealed structural changes of the studied components of the prostate dominated in 24-month-old experimental animals.

CONCLUSION

Conclusions: Morphological analysis of the prostate gland established that morphometric and morphological changed significantly according to the age and were depend on the ethanol poisoning.

Fetal programming by high-fat diet promoted the decreased of the prostate in adult Wistar albino rats

We investigated the effect of a high-fat diet on body metabolism and ventral prostate morphology in 4-months-old offspring. The mother was fed with a control (C) or a high-fat (HF) diet during gestation and lactation. At weaning, the offspring diet remained the same (C/C, n = 8; HF/HF, n = 8) or it was switched (C/HF, n = 8; HF/C, n = 9). Biometry, blood pressure (BP), glucose, lipid metabolism and ventral prostate were evaluated. Triacylglycerol of HF/C increased, and the C/HF group had decreased HDL-c levels (P = 0.0005 and P = 0.0100, respectively). All groups on the HF diet presented hyperglycemia (P = 0.0064). Serum testosterone diminished in the C/HF group (P = 0.0218). The HF diet, regardless of the period, reduced prostatic acinar area (P < 0.0001). The epithelium height was smaller in HF/C and HF/HF groups compared with C/C and C/HF (P < 0.0001), and the volume density of epithelium was lower in HF/C group compared with the C/C and C/HF (P = 0.0024). The volume density of smooth muscle cells diminished in C/HF and HF/C (P = 0.0013), and the volume density of connective tissue was reduced in HF/C and HF/HF (P < 0.0001). High-fat diet intake during prenatal and postnatal life leads to prostatic atrophy, which may impair prostate secretory activity and contractility, and thus disturb reproductive function in adulthood.

The essential role of GATA transcription factors in adult murine prostate

GATA transcription factors are essential in mammalian cell lineage determination and have a critical role in cancer development. In cultured prostate cancer cells, GATA2 coordinates with androgen receptor (AR) to regulate gene transcription. In the murine prostate, among six GATA members, GATA2 and GATA3 are expressed. Immunofluorescence staining revealed that both GATA factors predominantly localize in the nuclei of luminal epithelial cells. The pioneer factor FoxA1 is exclusively detected in the luminal cells, whereas AR is detected in both luminal and basal cells. Using genetic engineering, we generated prostate-specific GATA2 and GATA3 knockout (KO) mice. Ablation of single GATA gene had marginal effect on prostate morphology and AR target gene expression, likely due to their genetic compensation. Double KO mice exhibited PIN III to IV lesions, but decreased prostate to body weight ratio, altered AR target gene expression, and expansion of p63-positive basal cells. However, deletion of GATA2 and GATA3 did not reduce the mRNA or protein levels of AR or FoxA1, indicating that GATA factors are not required for AR or FoxA1 expression in adult prostate. Surprisingly, GATA2 and GATA3 exhibit minimal expression in the ventral prostatic (VP) lobe. In contrast, FoxA1 and AR expression levels in VP are at least as high as those in anterior prostatic (AP) and dorsal-lateral prostatic (DLP) lobes. Together, our results indicate that GATA2 and GATA3 are essential for adult murine prostate function and in vivo AR signaling, and the lack of the GATA factor expression in the VP suggests a fundamental difference between VP and other prostatic lobes.

Potential use of chymotrypsin-like proteasomal activity as a biomarker for prostate cancer

Although it is the most widely used biomarker for prostate cancer, the use of prostate specific antigen (PSA) is controversial due to its limitations in specificity and sensitivity. The proteasome is a complex associated with cell proliferation and apoptosis, and the abnormity of these processes may lead to tumor occurrence. Previous studies have reported that proteasomal activity is associated with cancer progression and can be used in risk stratification. The purpose of the present study was thus to investigate the feasibility of proteasome activity as a biomarker for prostate cancer. Proteasome activity in vitro and in vivo was detected, along with the expression of the substrate proteins NF-κB inhibitor-α (IκB-α), Bcl-2-associated X (Bax) and p27. Chymotrypsin-like proteasomal activity was elevated by 70% in vitro and 23% in vivo, and the expression levels of the proteasome substrate proteins IκB-α, Bax and p27 were decreased in prostate cancer cells and prostate tumor xenografts compared with normal mouse prostate tissue. In conclusion, proteasomal chymotrypsin-like activity maybe a potential biomarker for prostate cancer, and may be suitable to supplement PSA in clinical application for prostate cancer diagnosis.

Oxytocin: its role in benign prostatic hyperplasia via the ERK pathway

The aim of the present study was to evaluate oxytocin and benign prostatic hyperplasia (BPH), and study the cell signalling mechanism. Investigation was performed in patients about the correlation between oxytocin level and BPH. Mice were injected with oxytocin or oxytocin antagonist for 2 weeks and the prostate morphology was studied after their sacrifice. Furthermore, in vitro experiments were performed to evaluate the oxytocin effect through the MEK/ERK/RSK pathway. Oxytocin was significantly elevated in the serum and prostate tissue of patients with BPH, and a positive correlation with prostate volume indicated. In the animal experiments, prostate enlargement was observed in the oxytocin-treated group, whereas oxytocin antagonist reduced prostate hyperplasia. The in vitro study confirmed this result and also revealed activation of the MEK/ERK/RSK pathway. Oxytocin is highly expressed in the serum and prostate tissue of patients with BPH. In addition, oxytocin aggravates BPH and the oxytocin-induced proliferative effect on prostatic cells is mediated through the MEK/ERK/RSK pathway, at least partly. Thus, the hypothalamic regulation may be involved in development of BPH, which may open a new door to more medications for BPH in the future.

The mouse prostate: a basic anatomical and histological guideline

Despite substantial similarities in embryological, cellular and molecular biology features, human and mouse prostates differ in organ morphology and tissue architecture. Thus, a clear understanding of the anatomy and histology of the mouse prostate is essential for the identification of urogenital phenotypes in genetically engineered mice, as well as for the study of the etiology, development, and treatment of human prostatic diseases for which mouse models are used. The purpose of this manuscript is to provide a brief guide for the dissection of the mouse prostate and the identification of its different lobes and histology, to both basic researchers and medical pathologists who are unfamiliar with mouse tissues.

Developmental exposure to estrogen alters differentiation and epigenetic programming in a human fetal prostate xenograft model

Prostate cancer is the most frequent non-cutaneous malignancy in men. There is strong evidence in rodents that neonatal estrogen exposure plays a role in the development of this disease. However, there is little information regarding the effects of estrogen in human fetal prostate tissue. This study explored early life estrogen exposure, with and without a secondary estrogen and testosterone treatment in a human fetal prostate xenograft model. Histopathological lesions, proliferation, and serum hormone levels were evaluated at 7, 30, 90, and 200-day time-points after xenografting. The expression of 40 key genes involved in prostatic glandular and stromal growth, cell-cycle progression, apoptosis, hormone receptors and tumor suppressors was evaluated using a custom PCR array. Epigenome-wide analysis of DNA methylation was performed on whole tissue, and laser capture-microdissection (LCM) isolated epithelial and stromal compartments of 200-day prostate xenografts. Combined initial plus secondary estrogenic exposures had the most severe tissue changes as revealed by the presence of hyperplastic glands at day 200. Gene expression changes corresponded with the cellular events in the KEGG prostate cancer pathway, indicating that initial plus secondary exposure to estrogen altered the PI3K-Akt signaling pathway, ultimately resulting in apoptosis inhibition and an increase in cell cycle progression. DNA methylation revealed that differentially methylated CpG sites significantly predominate in the stromal compartment as a result of estrogen-treatment, thereby providing new targets for future investigation. By using human fetal prostate tissue and eliminating the need for species extrapolation, this study provides novel insights into the gene expression and epigenetic effects related to prostate carcinogenesis following early life estrogen exposure.

A human fetal prostate xenograft model of developmental estrogenization

Prostate cancer is a common disease in older men. Rodent models have demonstrated that an early and later-life exposure to estrogen can lead to cancerous lesions and implicated hormonal dysregulation as an avenue for developing future prostate neoplasia. This study utilizes a human fetal prostate xenograft model to study the role of estrogen in the progression of human disease. Histopathological lesions were assessed in 7-, 30-, 90-, 200-, and 400-day human prostate xenografts. Gene expression for cell cycle, tumor suppressors, and apoptosis-related genes (ie, CDKN1A, CASP9, ESR2, PTEN, and TP53) was performed for 200-day estrogen-treated xenografts. Glandular hyperplasia was observed in xenografts given both an initial and secondary exposure to estradiol in both 200- and 400-day xenografts. Persistent estrogenic effects were verified using immunohistochemical markers for cytokeratin 10, p63, and estrogen receptor α. This model provides data on the histopathological state of the human prostate following estrogenic treatment, which can be utilized in understanding the complicated pathology associated with prostatic disease and early and later-life estrogenic exposures.

Anatomical and immunohistochemical characteristics of the prostate gland in the greater cane rat (Thryonomys swinderianus)

This study examined the morphology and immunohistochemical features of the prostate gland in 15 captive-reared male greater cane rat of known reproductive and medical history. Samples of the glands were taken after gross examination and routinely prepared for both histological and ultrastructural analysis. Immunohistochemistry was also carried out on paraffin-embedded sections of the glands using rabbit polyclonal antibodies against oestrogen receptors (ERα and ERβ) and mouse monoclonal antibody for the progesterone receptor (PR). The prostate, which constitutes 0.04% of the body weight, was a paired, lobulated, brownish gland having three left and four right lobes that partly cover the pelvic urethra. Based on the amount and arrangement of the secretory epithelial folding and relative to their distances to the urethra, two histological zones, the central and peripheral, were identified. However, the epithelium of both zones was lined by predominantly simple cuboidal cells with occasional basal cells. The main ultrastructural features of these cuboidal cells were the presence of several nuclear pores on the nucleus, moderately well-developed, short microvilli and bleb-like apical projections, as well as inter-cellular lacunae seen between these cells and the basal cells. The cuboidal epithelial cells also showed positive nuclear staining for ERα and ERβ but not for PR. It is however interesting that the ERα-positive staining was more at the epithelial cells, which is uncommon. These findings highlight the peculiarities in the structure and ultrastructure as well as the unique expression of the oestrogen receptors in the prostate gland of the greater cane rat.

Maturation of the developing human fetal prostate in a rodent xenograft model

BACKGROUND

Prostate cancer is the most commonly diagnosed nonskin cancer in men. The etiology of prostate cancer is unknown, although both animal and epidemiologic data suggest that early life exposures to various toxicants, may impact DNA methylation status during development, playing an important role.

METHODS

We have developed a xenograft model to characterize the growth and differentiation of human fetal prostate implants (gestational age 12-24 weeks) that can provide new data on the potential role of early life stressors on prostate cancer. The expression of key immunohistochemical markers responsible for prostate maturation was evaluated, including p63, cytokeratin 18, α-smooth muscle actin, vimentin, caldesmon, Ki-67, prostate-specific antigen, estrogen receptor-α, and androgen receptor. Xenografts were separated into epithelial and stromal compartments using laser capture microdissection (LCM), and the DNA methylation status was assessed in >480,000 CpG sites throughout the genome.

RESULTS

Xenografts demonstrated growth and maturation throughout the 200 days of post-implantation evaluation. DNA methylation profiles of laser capture microdissected tissue demonstrated tissue-specific markers clustered by their location in either the epithelium or stroma of human prostate tissue. Differential methylated promoter region CpG-associated gene analysis revealed significantly more stromal than epithelial DNA methylation in the 30- and 90-day xenografts. Functional classification analysis identified CpG-related gene clusters in methylated epithelial and stromal human xenografts.

CONCLUSION

This study of human fetal prostate tissue establishes a xenograft model that demonstrates dynamic growth and maturation, allowing for future mechanistic studies of the developmental origins of later life proliferative prostate disease.

Overview of prostate anatomy, histology, and pathology

The human prostate is heterogeneous with regard to its embryologic origin. The two most prevalent diseases of aging males, benign prostatic hyperplasia and prostate cancer (PCa), arise from different zones within the prostate. The biology of PCa is also heterogeneous and even within a single individual there often exist prostate cancers with varying potential to progress and metastasize. Through careful study of the histology and molecular signatures of both the human and mouse-modeled disease, treatment decisions can be tailored to individual cases so as to optimize efficacy and minimize side effects from therapy.

Normal prostate morphology in relaxin-mutant mice

The peptide hormone relaxin is expressed in the prostate gland and secreted into the seminal plasma; however, its function within the prostate has not been established. Relaxin-mutant mice (Rln–/–) were reported to have abnormal prostate morphology, but there was no prostate phenotype in relaxin receptor-mutant (Rxfp1–/–) mice. The present study aimed to verify the phenotypes in the anterior, dorsal and lateral lobes of the prostate gland of Rln–/– and Rxfp1–/– mice at different adult ages. Rln–/– mice were also treated with relaxin to evaluate the effects of exogenously administered hormone on prostate morphology. Comparisons between these three lobes of the prostate demonstrated no obvious differences in duct morphology, epithelial height or collagen density between Rln+/+ and Rln–/– mice at 2, 4, 6, 8 and 12 months of age. This was similar in Rxfp1–/– mice. Relaxin treatment did not affect morphology or epithelial cell height in the different lobes. Furthermore, prostate lobe morphology in transgenic mice overexpressing relaxin Tg(Rln) was not different from the wild-type controls. Rxfp1 was detected in the prostate throughout adult life, but there was no consistent expression of relaxin. In summary, the present study found no evidence to support a prostate phenotype in adult Rln- or Rxfp1-mutant mice.