Regional variations of insulin-like growth factor I (IGF-I), IGF-II, and receptor type I in benign prostatic hyperplasia tissue and their correlation with intraprostatic androgens

Mechanistic targets for BPH and prostate cancer-a review

All men, almost, suffer from prostatic disorders in average life expectancy. In the year of 1950s, the first autopsy of prostate gland discovered the link between Benign prostatic hyperplasia (BPH) and Prostate Cancer (PCa). After that, many histology, biochemistry, epidemiology studies explained the association and associated risk factor for the same. From the various scientific evidence, it is proved that both diseases share some common transcription factors and signalling pathways. Still, BPH cannot be considered as the first step of PCa progression. To define, the relationship between both of the diseases, a well-defined large epidemiological study is needed. Along with androgen signalling, imbalanced apoptosis, oxidative stress, and microbial infection also crucial factors that significantly affect the pathogenesis of BPH. Various signalling pathways are involved in the progression of BPH. Androgen signalling is the driving force for the progress of PCa. In PCa androgen signalling is upregulated as compared to a healthy prostate. Some dominant Androgen-regulated genes and their functions have been discussed in this work.

Effects of metformin on prostatic tissue of rats with metabolic syndrome and benign prostatic hyperplasia

OBJECTIVES

To investigate the efficacy of insulin sensitizer on prostatic tissue in animal model with benign prostatic hyperplasia (BPH) secondary to metabolic syndrome (MetS).

METHODS

Models were established by providing Sprague-Dawley rats with high fat diet (HFD) combined with metformin or not. All objects were killed 40 days later with prostatic tissue being removed, weighed before stained, as well as the expression level of insulin-like growth factor I (IGF-1) and receptor (IGF-1R) being measured, and the level of insulin resistance (IR) has also been evaluated.

RESULTS

Model has been successfully established. Level of prostatic hyperplasia and IR as well as IGF-1 and IGF-1R expressions in the blank and saline control subunits of HFD group was higher than that of normal diet group (P < 0.05). In the subunit of metformin, along with the suppression of IR, the level of prostatic hyperplasia and the expression of IGF-1 pathway have both decreased (P < 0.05).

CONCLUSION

MetS can promote the growth of prostate during the formation of central obesity and IR. IGF-1 pathway may have an important role in the induction of BPH following IR. The application of metformin can suppress the expression of IGF-1 and IGF-1R, thus preventing the promotive effect of IR on prostate tissue in animal model of MetS.

Influence of E. coli-induced prostatic inflammation on expression of androgen-responsive genes and transforming growth factor beta 1 cascade genes in rats

BACKGROUND

Prostatic inflammation is reportedly associated with the development of prostatic hyperplasia. We investigated the effects of prostatic inflammation on expression levels of androgen-responsive genes and growth factors in the rat prostate.

METHODS

Prostatic inflammation was induced by Escherichia coli (strain 1677) injection (0.2 ml of 1 × 10(8) CFU/ml) into the prostatic urethra of male Sprague-Dawley rats, and ventral lobes of the prostate were harvested on day 84. Rats were given 10 mg/kg celecoxib during the last month in the COX-2 inhibitor treated group. Histopathology and multiplex enzyme-linked immunosorbent assay (ELISA) for inflammation-related proteins were performed. Glandular epithelial cells and stromal regions were separately isolated using laser-capture microdissection (LCM). Real-time RT-PCR was performed to examine mRNA levels of androgen-responsive genes in the epithelium and tumor growth factor-β1 (TGF-β1) cascade genes in the stroma.

RESULTS

Hematoxylin and eosin staining showed that mild inflammation was distributed diffusely throughout the prostate. Polymorphonuclear cells infiltrated the slightly edematous stroma, but no morphological changes were observed in the epithelium. Immunohistochemically, expression of androgen receptor and TGF-β1 in addition to IL-6 and cyclooxigenase-2 (COX-2) were enhanced in the E. coli inoculated rats. All of these factors were suppressed in the celecoxib-treated rats. Upregulation of IL-1α, IL-1β, IL-6, and RANTES in the E. coli-inoculated rats was normalized by celecoxib treatment. Significant upregulation of androgen receptor and androgen-responsive genes such as Eaf2, ELL2, FKBP5, calreticulin, and ornithine decarboxylase was observed in the LCM-dissected epithelium. Also TGF-β1 and its downstream cascade genes such as Hic-5, collagen 1, and fibronectin were upregulated significantly in the LCM-dissected stroma. The COX-2 inhibitor treatment suppressed upregulation of these genes.

CONCLUSIONS

Prostatic inflammation changed the expression of androgen-responsive genes in the epithelium and TGF-β1 cascade genes in the stroma. Activation of TGF-β1 cascade genes in the inflamed stroma, as well as altered androgen-responsive gene expression in the epithelium, might be involved in the development of BPH. Prostate 75:381-389, 2015. © 2014 Wiley Periodicals, Inc.

Interleukin-driven insulin-like growth factor promotes prostatic inflammatory hyperplasia

Prostatic inflammation is of considerable importance to urologic research because of its association with benign prostatic hyperplasia and prostate cancer. However, the mechanisms by which inflammation leads to proliferation and growth remain obscure. Here, we show that insulin-like growth factors (IGFs), previously known as critical developmental growth factors during prostate organogenesis, are induced by inflammation as part of the proliferative recovery to inflammation. Using genetic models and in vivo IGF receptor blockade, we demonstrate that the hyperplastic response to inflammation depends on interleukin-1-driven IGF signaling. We show that human prostatic hyperplasia is associated with IGF pathway activation specifically localized to foci of inflammation. This demonstrates that mechanisms of inflammation-induced epithelial proliferation and hyperplasia involve the induction of developmental growth factors, further establishing a link between inflammatory and developmental signals and providing a mechanistic basis for the management of proliferative diseases by IGF pathway modulation.

Linking pre-diabetes with benign prostate hyperplasia. IGFBP-3: a conductor of benign prostate hyperplasia development orchestra?

Benign prostatic hyperplasia (BPH) represents a pattern of non-malignant growth of prostatic fibromuscular stroma. Metabolic disturbances such us pre-diabetes and metabolic syndrome may have a role in BPH pathophysiology. A potential explanation for the above relationship involves the insulin-like growth factor (IGF) axis as well as IGF binding proteins, (IGFBPs) of which the most abundant form is IGFBP-3. Therefore, the aim of the present study was to investigate the association between intra-prostatic levels of IGF-1, IGF-2 as well as to evaluate the role of locally expressed IGFBP-3 in BPH development in pre-diabetes. A total of 49 patients admitted to the Urology department of a tertiary urban Greek hospital, for transurethral prostate resection, or prostatectomy and with pre-diabetes [impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) or both] were finally included. The majority of the sample consisted of subjects with IGT (51.0%), followed by IFG and IGT (32.7%) and isolated IFG (16.3%). For all participants a clinical examination was performed and blood samples were collected. In addition, total prostate (TP) volume or transitional zone (TZ) volume were estimated by transrectal ultrasonography. The results of the multivariate analysis regarding TP volume showed that higher PSA (p<0.001), larger waist circumference (p=0.007) and higher IGFBP-3 expression levels (p<0.001) independently predicted higher TP volume. The results regarding the volume of the TZ showed that higher PSA (p<0.001), larger waist circumference (p<0.001) and higher IGFBP-3 expression levels (p=0.024) were independently associated with higher TZ volume. Our findings show that intra-prostatic levels of IGFBP-3, PSA and waist circumference, but not overall obesity, are positively associated with prostate volume. IGFBP-3 seems to be a multifunctional protein, which can potentiate or inhibit IGF activity.

Androgen receptor roles in the development of benign prostate hyperplasia

Benign prostate hyperplasia (BPH) is a major cause of lower urinary tract symptoms, with an increased volume of transitional zone and associated with increased stromal cells. It is known that androgen/androgen receptor (AR) signaling plays a key role in development of BPH, and that blockade of this signaling decreases BPH volume and can relieve lower urinary tract symptoms, but the mechanisms of androgen/AR signaling in BPH development remain unclear, and the effectiveness of current drugs for treating BPH is still limited. The detailed mechanisms of androgen/AR signaling need to be clarified, and new therapies are needed for better treatment of BPH patients. This review focuses on roles of AR in epithelial and stromal cells in BPH development. In epithelial cells, AR may contribute to BPH development via epithelial cell-stromal cell interaction with alterations of epithelial-mesenchymal transition, leading to proliferation of stromal cells. Data from several mouse models with selective knockout of AR in stromal smooth-muscle cells and/or fibroblasts indicate that the AR in stromal cells can also promote BPH development. In prostatic inflammation, AR roles in infiltrating macrophages and epithelial and stromal cells have been linked to BPH development, which has led to discovery of new therapeutic targets. For example, targeting AR with the novel AR degradation enhancer, ASC-J9 offers a potential therapeutic approach against BPH development.

The impact of diabetes type 2 in the pathogenesis of benign prostatic hyperplasia: a review

Introduction. Clinical observation of larger prostate glands in men with diabetes mellitus type 2 led some investigators to hypothesize that an association between these two conditions exists. In fact, both diseases are very common in men as they age and seem to be sharing similar epidemiologic features. Several studies examining the above hypothesis were yielded. Aim. The purpose of this paper is to summarize the existing literature focusing on the coexistence of BPH and diabetes mellitus type 2 and to elucidate whether or not an association among these conditions exists. Methods. We identified studies published from 1990 onwards by searching the MEDLINE database of the National Library of Medicine. Initial search terms were benign prostatic hyperplasia, epidemiology, and risk factor, combined with diet hyperinsulinemia, and diabetes mellitus type 2. Results. Diabetes mellitus type 2 and hyperinsulinemia are quite common conditions and often coexist with BPH. There are several studies (observational, epidemiological, and experimental) examining the association between them in literature. Conclusion. Evidence suggests that an association between BPH and diabetes through a common pathogenic mechanism is possible. The specific pathway interfering in the development of both conditions is still poorly investigated; thus, the exact relationship of BPH to diabetes remains unclear.

Insulin regulates glucagon-like peptide-1 secretion from the enteroendocrine L cell

Insulin resistance and type 2 diabetes mellitus are associated with impaired postprandial secretion of glucagon-like peptide-1 (GLP-1), a potent insulinotropic hormone. The direct effects of insulin and insulin resistance on the L cell are unknown. We therefore hypothesized that the L cell is responsive to insulin and that insulin resistance impairs GLP-1 secretion. The effects of insulin and insulin resistance were examined in well-characterized L cell models: murine GLUTag, human NCI-H716, and fetal rat intestinal cells. MKR mice, a model of chronic hyperinsulinemia, were used to assess the function of the L cell in vivo. In all cells, insulin activated the phosphatidylinositol 3 kinase-Akt and MAPK kinase (MEK)-ERK1/2 pathways and stimulated GLP-1 secretion by up to 275 +/- 58%. Insulin resistance was induced by 24 h pretreatment with 10(-7) m insulin, causing a marked reduction in activation of Akt and ERK1/2. Furthermore, both insulin-induced GLP-1 release and secretion in response to glucose-dependent insulinotropic peptide and phorbol-12-myristate-13-acetate were significantly attenuated. Whereas inhibition of phosphatidylinositol 3 kinase with LY294002 potentiated insulin-induced GLP-1 release, secretion was abrogated by inhibiting the MEK-ERK1/2 pathway with PD98059 or by overexpression of a kinase-dead MEK1-ERK2 fusion protein. Compared with controls, MKR mice were insulin resistant and displayed significantly higher fasting plasma insulin levels. Furthermore, they had significantly higher basal GLP-1 levels but displayed impaired GLP-1 secretion after an oral glucose challenge. These findings indicate that the intestinal L cell is responsive to insulin and that insulin resistance in vitro and in vivo is associated with impaired GLP-1 secretion.

Growth factors in benign prostatic hyperplasia: basic science implications

Benign prostatic hyperplasia (BPH) is the most common proliferative disease of the prostate of men in the United States. The histopathology of BPH strongly implicates local paracrine and autocrine growth factors and inflammatory cytokines in its pathogenesis. A complex milieu of growth-regulatory proteins includes members of the fibroblast, insulin-like, and transforming growth factor families. It appears that these proteins and downstream effector molecules, in addition to a variety of interleukins, are overexpressed in BPH and, working together, create a landscape of increased stromal and epithelial growth and mesenchymal transdifferentiation that leads to disease progression. Inflammation, commonly present in BPH, may contribute to tissue injury, and cytokines produced by inflammatory cells may serve to drive local growth factor production and angiogenesis in the tissues as a "wound healing" response. As we begin to unravel the precise mechanisms involved, new treatments for BPH aimed at these interacting pathways may emerge.