Vascular endothelial growth factor and angiopoietin are required for prostate regeneration

Understanding human aging and the fundamental cell signaling link in age-related diseases: the middle-aging hypovascularity hypoxia hypothesis

Aging-related hypoxia, oxidative stress, and inflammation pathophysiology are closely associated with human age-related carcinogenesis and chronic diseases. However, the connection between hypoxia and hormonal cell signaling pathways is unclear, but such human age-related comorbid diseases do coincide with the middle-aging period of declining sex hormonal signaling. This scoping review evaluates the relevant interdisciplinary evidence to assess the systems biology of function, regulation, and homeostasis in order to discern and decipher the etiology of the connection between hypoxia and hormonal signaling in human age-related comorbid diseases. The hypothesis charts the accumulating evidence to support the development of a hypoxic milieu and oxidative stress-inflammation pathophysiology in middle-aged individuals, as well as the induction of amyloidosis, autophagy, and epithelial-to-mesenchymal transition in aging-related degeneration. Taken together, this new approach and strategy can provide the clarity of concepts and patterns to determine the causes of declining vascularity hemodynamics (blood flow) and physiological oxygenation perfusion (oxygen bioavailability) in relation to oxygen homeostasis and vascularity that cause hypoxia (hypovascularity hypoxia). The middle-aging hypovascularity hypoxia hypothesis could provide the mechanistic interface connecting the endocrine, nitric oxide, and oxygen homeostasis signaling that is closely linked to the progressive conditions of degenerative hypertrophy, atrophy, fibrosis, and neoplasm. An in-depth understanding of these intrinsic biological processes of the developing middle-aged hypoxia could provide potential new strategies for time-dependent therapies in maintaining healthspan for healthy lifestyle aging, medical cost savings, and health system sustainability.

KLK3 in the Regulation of Angiogenesis-Tumorigenic or Not?

In this focused review, we address the role of the kallikrein-related peptidase 3 (KLK3), also known as prostate-specific antigen (PSA), in the regulation of angiogenesis. Early studies suggest that KLK3 is able to inhibit angiogenic processes, which is most likely dependent on its proteolytic activity. However, more recent evidence suggests that KLK3 may also have an opposite role, mediated by the ability of KLK3 to activate the (lymph)angiogenic vascular endothelial growth factors VEGF-C and VEGF-D, further discussed in the review.

Role of androgens for urethral homeostasis

Background

We observed that patients with hypogonadism are at higher risk to experience artificial urinary sphincter cuff erosion. Sphincter erosions have been found to be associated with urethral atrophy or compromised urethras subsequent to events limiting its blood supply. We therefore analyzed possible mechanisms how a decrease in testosterone serum levels can result decreased urethral blood flow.

Methods

In a cohort of >1,200 urethroplasties, tissue specimens obtained during surgeries were analyzed for expression of androgen receptor (AR), AR-responsive TIE-2 associated with angiogenesis, and the endothelial cell marker CD31 for determination of vessel counts were analyzed immunohistochemically. A total of 11 patients were included in whom both tissue and serum testosterone levels within 2 years of the urethroplasty was available. Low serum testosterone level defined as <280 ng/dL. Image J software was used to analyze expression profiles.

Results

Mean serum testosterone level was significant lower in hypogonadal patients (179.4 ng/dL) compared to eugonadal patients (375.0 ng/dL, P=0.003). Urethral tissue of hypogonadal patients showed decreased AR expression [1.11% high power field (HPF)] compared to eugonadal patients (1.62%, P=0.016), decreased TIE-2 expression (1.84% HPF vs. 3.08%, P=0.006), and also decreased vessel counts (44.47 vessels/HPF vs. 98.33, P=0.004). There was a direct correlation of AR and TIE-2 expression levels with serum testosterone levels (rho 0.685, P=0.029, and rho 0.773, P=0.005, respectively). Of note, we did not detect a difference in age, prior radiation, coronary artery disease or hypertension among hypo- or eugonadal patient. However, higher body mass index was associated with low serum testosterone levels.

Conclusions

Hypogonadal status is associated with decreased expression of AR and TIE-2 and also reduced vessel count in urethral tissue. We believe that the resulting decreased urethral vascularity subsequent to a hypogonadal state may be an important risk factor for complications of urethral surgery.

Role of Stromal Paracrine Signals in Proliferative Diseases of the Aging Human Prostate

Androgens are essential for the development, differentiation, growth, and function of the prostate through epithelial–stromal interactions. However, androgen concentrations in the hypertrophic human prostate decrease significantly with age, suggesting an inverse correlation between androgen levels and proliferative diseases of the aging prostate. In elderly males, age- and/or androgen-related stromal remodeling is spontaneously induced, i.e., increased fibroblast and myofibroblast numbers, but decreased smooth muscle cell numbers in the prostatic stroma. These fibroblasts produce not only growth factors, cytokines, and extracellular matrix proteins, but also microRNAs as stromal paracrine signals that stimulate prostate epithelial cell proliferation. Surgical or chemical castration is the standard systemic therapy for patients with advanced prostate cancer. Androgen deprivation therapy induces temporary remission, but the majority of patients eventually progress to castration-resistant prostate cancer, which is associated with a high mortality rate. Androgen deprivation therapy-induced stromal remodeling may be involved in the development and progression of castration-resistant prostate cancer. In the tumor microenvironment, activated fibroblasts stimulating prostate cancer cell proliferation are called carcinoma-associated fibroblasts. In this review, we summarize the role of stromal paracrine signals in proliferative diseases of the aging human prostate and discuss the potential clinical applications of carcinoma-associated fibroblast-derived exosomal microRNAs as promising biomarkers.

Changes in Lymphangiogenesis and Vascular Endothelial Growth Factor Expression by Neo-Adjuvant Hormonal Therapy in Prostate Cancer Patients

BACKGROUND

The anti-cancer mechanism of neo-adjuvant hormonal therapy (NHT) is not well understood. Lymphangiogenesis plays an important role in cancer progression and is regulated by a complex mechanism that includes vascular endothelial growth factor (VEGF) signaling. However, there is little information regarding relationship between lymphangiogenesis and androgen deprivation. The aim of this study was to clarify changes in lymphangiogenesis and VEGF expression induced by androgen deprivation in prostate cancer in vivo and in vitro.

METHODS

Patients who had undergone a radical prostatectomy were enrolled in the study (NHT, n = 60 and non-NHT, n = 64). Lymph vessels were identified by D2-40 immunoreactivity and lymph vessel density and lymph vessel area (LVD and LVA, respectively) were measured from micrographs. The expression of VEGF-A, -B, -C, and -D was evaluated by immunohistochemistry. The prognostic value of LVD and LVA for biochemical recurrence was also investigated.

RESULTS

Mean LVD ± SD was higher in the NHT than in the non-NHT group (11.3 ± 3.0 vs. 7.1 ± 3.4 per high power field; P < 0.001). LVA was larger in the NHT than in the non-NHT group (512.8 ± 174.9 vs. 202.7 ± 72.8 µm² ; P < 0.001). VEGF-A expression was lower whereas VEGF-C and -D levels were higher in the NHT than in the non-NHT group. VEGF-B expression in specimens with NHT was lower than that in biopsy specimens at diagnosis. These results were confirmed by in vitro studies used androgen-sensitive prostate cancer cell line. LVA was found to be an independent predictor of biochemical recurrence in patients who received NHT.

CONCLUSIONS

Our results demonstrate that NHT stimulates lymphangiogenesis via upregulation of VEGF-C and -D, which may increase LVA and affect the outcome of prostate cancer patients. This findings were supported by in vitro data of prostate cancer cell. Prostate 77:255-262, 2017. © 2016 The Authors. The Prostate Published by Wiley Periodicals, Inc.

Androgen Receptor-Mediated Genomic Androgen Action Augments Ischemia-Induced Neovascularization

Increasing evidence indicates that androgens regulate ischemia-induced neovascularization. However, the role of genomic androgen action mediated by androgen receptor (AR), a ligand-activated nuclear transcription factor, remains poorly understood. Using an AR knockout (KO) mouse strain that contains a transcriptionally inactive AR (AR^Δex3KO), we examined the role of AR genomic function in modulating androgen-mediated augmentation of ischemia-induced neovascularization. Castrated wild-type (AR^WT) and AR^Δex3KO mice were implanted with 5α-dihydrotestosterone (DHT) or placebo pellets after hindlimb ischemia (HLI). DHT modulation of angiogenesis and vasculogenesis, key processes for vascular repair and regeneration, was examined. Laser Doppler perfusion imaging revealed that DHT enhanced blood flow recovery in AR^WT mice post-HLI. In AR^WT mice, DHT enhanced angiogenesis by down-regulating prolyl hydroxylase 2 and augmenting hypoxia-inducible factor-1α (HIF-1α) levels in the ischemic tissues post-HLI. DHT also enhanced the production and mobilization of Sca1+/CXCR4+ progenitor cells in the bone marrow (BM) and circulating blood, respectively, in AR^WT mice. By contrast, DHT-mediated enhancement of blood flow recovery was abrogated in AR^Δex3KO mice. DHT modulation of HIF-1α expression was attenuated in AR^Δex3KO mice. DHT-induced HIF-1α transcriptional activity and DHT-augmented paracrine-mediated endothelial cell tubule formation were attenuated in fibroblasts isolated from AR^Δex3KO mice in vitro. Furthermore, DHT-induced augmentation of Sca1+/CXCR4+ progenitor cell production and mobilization was absent in AR^Δex3KO mice post-HLI. BM transplantation revealed that ischemia-induced mobilization of circulating progenitor cells was abolished in recipients of AR^Δex3KO BM. Together, these results indicate that androgen-mediated augmentation of ischemia-induced neovascularization is dependent on genomic AR transcriptional activation.

[Prostate cancer microenvironment: Its structure, functions and therapeutic applications]

INTRODUCTION

In the field of prostate cancer there is a growing tendency for more and more studies to emphasise the predominant role of the zone situated between the tumour and the host: the tumour microenvironment. The aim of this article is to describe the structure and the functions of the prostate cancer microenvironment as well as the principal treatments that are being applied to it.

MATERIAL AND METHODS

PubMed and ScienceDirect databases have been interrogated using the association of keywords "tumour microenvironment" and "neoplasm therapy" along with "microenvironnement tumoral" and "traitements". Of the 593 articles initially found, 50 were finally included.

RESULTS

The tumour microenvironment principally includes host elements that are diverted from their primary functions and encourage the development of the tumour. In it we find immunity cells, support tissue as well as vascular and lymphatic neovascularization. Highlighting the major role played by this microenvironment has led to the development of specific treatments, notably antiangiogenic therapy and immunotherapy.

CONCLUSION

The tumour microenvironment, the tumour and the host influence themselves mutually and create a variable situation over time. Improvement of the knowledge of the prostate cancer microenvironment gradually enables us to pass from an approach centred on the tumour to a broader approach to the whole tumoral ecosystem. This enabled the emergence of new treatments whose place in the therapeutic arsenal still need to be found.

Castration-resistant Lgr5(+) cells are long-lived stem cells required for prostatic regeneration

The adult prostate possesses a significant regenerative capacity that is of great interest for understanding adult stem cell biology. We demonstrate that leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) is expressed in a rare population of prostate epithelial progenitor cells, and a castration-resistant Lgr5⁺ population exists in regressed prostate tissue. Genetic lineage tracing revealed that Lgr5⁺ cells and their progeny are primarily luminal. Lgr5⁺ castration-resistant cells are long lived and upon regeneration, both luminal Lgr5⁺ cells and basal Lgr5⁺ cells expand. Moreover, single Lgr5⁺ cells can generate multilineage prostatic structures in renal transplantation assays. Additionally, Lgr5⁺ cell depletion revealed that the regenerative potential of the castrated adult prostate depends on Lgr5⁺ cells. Together, these data reveal insights into the cellular hierarchy of castration-resistant Lgr5+ cells, indicate a requirement for Lgr5⁺ cells during prostatic regeneration, and identify an Lgr5⁺ adult stem cell population in the prostate.

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Castration-resistant Lgr5⁺ basal and luminal cells exist in regressed prostate

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Lgr5⁺ castration-resistant cells are long lived

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During regeneration, Lgr5+ basal and luminal cells expand

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Prostate regeneration requires Lgr5+ cells

Anti-angiogenesis in prostate cancer: knocked down but not out

Angiogenesis is a very complex physiological process, which involves multiple pathways that are dependent on the homeostatic balance between the growth factors (stimulators and inhibitors). This tightly controlled process is stimulated by angiogenic factors, which are present within the tumor and surrounding tumor-associated stromal cells. The dependence of tumor propagation, invasion and metastasis on angiogenesis makes the inhibitors of new blood vessel formation attractive drugs for treating the malignancies. Angiogenesis can be disrupted by several distinct mechanisms: by inhibiting endothelial cells, by interrupting the signaling pathways or by inhibiting other activators of angiogenesis. This strategy has shown therapeutic benefit in several types of solid tumors, leading to Food and Drug Administration (FDA) approval of anti-angiogenic agents in the treatment of kidney, non-small cell lung, colon and brain cancers. Although no angiogenesis inhibitors have been approved for patients with metastatic prostate cancer, therapies that target new blood vessel formation are still an emerging and promising area of prostate cancer research.

Activation of FGF2-FGFR signaling in the castrated mouse prostate stimulates the proliferation of basal epithelial cells

The prostate gland is unique in that it undergoes rapid regression following castration but regenerates completely once androgens are replaced. Residual ductal components play an important role in the regeneration of a fully functional prostate. In this study, to examine how androgen status affects prostate structure and components, we conducted histopathological studies of the involuted and regenerated mouse dorsolateral prostate (DLP). In the castrated mouse DLP, the number of luminal epithelial cells decreased in a time-dependent manner. On Day 14 postandrogen replacement, the number of luminal epithelial cells was completely restored to the baseline level. In contrast, the number of basal epithelial cells gradually increased in the castrated mouse prostate. The Ki67-labeling index of prostate basal epithelial cells was significantly increased after castration. The number of basal epithelial cells decreased to baseline after androgen replacement. After castration, mRNA expression levels of specific growth factors, such as Fgf2, Fgf7, Hgf, Tgfa, and Tgfb, were relatively abundant in whole mouse DLPs. In organ culture experiments, basal epithelial proliferation was recapitulated in the absence of dihydrotestosterone (DHT). The proliferation of basal epithelial cells in the absence of DHT was suppressed by treatment with an FGF receptor inhibitor (PD173074). Moreover, FGF2 treatment directly stimulated the proliferation of basal epithelial cells. Taken together, these data indicated that the FGF2-FGF receptor signal cascade in the prostate gland may be one of the pathways stimulating the proliferation of basal epithelial cells in the absence of androgens.

Suppression of DHT-induced paracrine stimulation of endothelial cell growth by estrogens via prostate cancer cells

BACKGROUND

Androgen modulation of angiogenesis in prostate cancer may be not directly mediated by androgen receptor (AR) as AR is not detected in the prostatic endothelial cells.

METHODS

We examined the paracrine stimulation of cell proliferation by prostate tumor cells and its modulation by androgen and estrogens in a murine endothelial cell line (MEC) that does not express AR.

RESULTS

Tumor cell conditioned media (TCM) collected from LAPC-4 or LNCaP prostatic tumor cells produced a time- and concentration-dependent induction of cell growth in MECs, which was parallel to the VEGF concentration in the TCM. This TCM-induced cell growth in MECs was enhanced by the treatment of prostatic tumor cells with dihydrotestosterone (DHT). Both the TCM-stimulation and DHT-enhancement effects in MECs were completely blocked by SU5416, a specific VEGF receptor antagonist. Co-administration of 17α-estradiol or 17β-estradiol with DHT in prostatic tumor cells completely inhibited the DHT-enhancement effect while treatment with DHT, 17α-estradiol or 17β-estradiol did not produce any significant direct effect in MECs. Moreover, administration of 17α-estradiol or 17β-estradiol in xenograft animals with LAPC-4 or LNCaP prostate tumor significantly decreased the microvessel number in the tumor tissues.

CONCLUSIONS

Our study indicated that prostate tumor cells regulate endothelial cell growth through a paracrine mechanism, which is mainly mediated by VEGF; and DHT is able to modulate endothelial cell growth via tumor cells, which is inhibited by 17α-estradiol and 17β-estradiol. Thus, both17α-estradiol and 17β-estradiol are potential agents for anti-angiogenesis therapy in androgen-responsive prostate cancer.

Castration resistant prostate cancer is associated with increased blood vessel stabilization and elevated levels of VEGF and Ang-2

BACKGROUND

Angiogenesis is important for the progression of prostate cancer and may be a target for treatment in castration resistant (CR) disease. This study was performed to investigate blood vessel stabilization and expression of the pro-angiogenic factors vascular endothelial growth factor (VEGF) and Angiopoietin-2 (Ang-2) in CR and hormone naïve (HN) prostate cancer. The effect of androgen deprivation therapy (ADT) on these parameters was also studied.

METHODS

VEGF and Ang-2, as well as pericyte coverage of blood vessels were studied in HN and CR prostate tumors by immunohistochemistry. The effects of ADT on VEGF expression and microvessel density (MVD) were investigated in biopsies at diagnosis, 3 months after starting ADT and at tumor relapse. Plasma was also analyzed for VEGF and Ang-2 with ELISA.

RESULTS

CR tumors had higher levels of VEGF and Ang-2 as well as increased blood vessel stabilization compared to HN tumors. Three months after initiated ADT an increase of VEGF but not MVD in the tumors was observed. In contrast, plasma levels of VEGF decreased after ADT, and increased again at time of tumor relapse. Ang-2 levels were unaffected.

CONCLUSIONS

CR prostate cancer is associated with elevated levels of VEGF and Ang-2, indicating that these factors could be used as targets for anti-angiogenic treatment. Still, the observed increase in blood vessel stabilization in CR tumors could influence the outcome of anti-angiogenic treatment. Furthermore, increased VEGF expression after 3 months of ADT justifies the use of VEGF-based anti-angiogenic drugs in combination with ADT for the treatment of advanced prostate cancer.

Suppressed prostate epithelial development with impaired branching morphogenesis in mice lacking stromal fibromuscular androgen receptor

Using the cre-loxP system, we generated a new mouse model [double stromal androgen receptor knockout (dARKO)] with selectively deleted androgen receptor (AR) in both stromal fibroblasts and smooth muscle cells, and found the size of the anterior prostate (AP) lobes was significantly reduced as compared with those from wild-type littermate controls. The reduction in prostate size of the dARKO mouse was accompanied by impaired branching morphogenesis and partial loss of the infolding glandular structure. Further dissection found decreased proliferation and increased apoptosis of the prostate epithelium in the dARKO mouse AP. These phenotype changes were further confirmed with newly established immortalized prostate stromal cells (PrSC) from wild-type and dARKO mice. Mechanistically, IGF-1, placental growth factor, and secreted phosphoprotein-1 controlled by stromal AR were differentially expressed in PrSC-wt and PrSC-ARKO. Moreover, the conditioned media (CM) from PrSC-wt promoted prostate epithelium growth significantly as compared with CM from PrSC-dARKO. Finally, adding IGF-1/placental growth factor recombinant proteins into PrSC-dARKO CM was able to partially rescue epithelium growth. Together, our data concluded that stromal fibromuscular AR could modulate epithelium growth and maintain cellular homeostasis through identified growth factors.

Novel methods to identify biologically relevant genes for leukemia and prostate cancer from gene expression profiles

Background

High-throughput microarray experiments now permit researchers to screen thousands of genes simultaneously and determine the different expression levels of genes in normal or cancerous tissues. In this paper, we address the challenge of selecting a relevant and manageable subset of genes from a large microarray dataset. Currently, most gene selection methods focus on identifying a set of genes that can further improve classification accuracy. Few or none of these small sets of genes, however, are biologically relevant (i.e. supported by medical evidence). To deal with this critical issue, we propose two novel methods that can identify biologically relevant genes concerning cancers.

Results

In this paper, we propose two novel techniques, entitled random forest gene selection (RFGS) and support vector sampling technique (SVST). Compared with results from six other methods developed in this paper, we demonstrate experimentally that RFGS and SVST can identify more biologically relevant genes in patients with leukemia or prostate cancer. Among the top 25 genes selected using SVST method, 15 genes were biologically relevant genes in patients with leukemia and 13 genes were biologically relevant genes in patients with prostate cancer. Meanwhile, the RFGS method, while less effective than SVST, still identified an average of 9 biologically relevant genes in both leukemia and prostate cancers. In contrast to traditional statistical methods, which only identify less than 8 genes in patients with leukemia and less than 8 genes in patients with prostate cancer, our methods yield significantly better results.

Conclusions

Our proposed SVST and RFGS methods are novel approaches that can identify a greater number of biologically relevant genes. These methods have been successfully applied to both leukemia and prostate cancers. Research in the fields of biology and medicine should benefit from the identification of biologically relevant genes by confirming recent discoveries in cancer research or suggesting new avenues for exploration.

Inhibition of transforming growth factor-beta, hypoxia-inducible factor-1alpha and vascular endothelial growth factor reduced late rectal injury induced by irradiation

Tumor hypoxia and angiogenesis associated with malignant progression have been studied widely. The efficacy of angiogenesis inhibition combined with radiotherapy has been demonstrated in cancer treatment. Here, we studied the effect of hypoxia and angiogenesis inhibition on radiation-induced late rectal injury. The rectum of C57BL/6N mice was irradiated locally with a single dose of 25 Gy. Radiation-induced histological changes were examined at 90 days after irradiation by hematoxylin-eosin (H.E.) staining and azan staining. Pimonidazole was administered and its distribution was assayed by immunohistochemistry staining. Expression of transforming growth factor beta1 (TGF-beta1), hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) was assessed on the fibrotic region using real-time PCR and immunohistochemistry. In addition, the effects of TGF-beta, VEGF and HIF-1alpha on radiation-induced injury were investigated by the administration of neutralizing antibody of TGF-beta, antibody of VEGF or YC-1 (3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole) which was developed as an agent for inhibiting HIF-1 expression after irradiation respectively. Fibrosis and uptake of pimonidazole were found 90 days after irradiation. The expression of TGF-beta1, HIF-1alpha and VEGF significantly increased with the formation of fibrosis induced by irradiation compared with unirradiated controls. In addition, treatment of neutralizing antibody of TGF-beta, antibody of VEGF or YC-1 reduced the development of radiation-induced injury. Our results suggested that radiation-induced hypoxia may play an important role in late rectal injury. Although the inhibition of HIF-1alpha and VEGF reduced the radiation induced late injury, the precise mechanism is still unclear.

Endothelial cells support the growth of prostate tissue in vivo

INTRODUCTION

The contribution of vascular endothelial cells to prostate growth has not been investigated. We examined whether endothelial cells support growth of prostate tissue when co-inoculated with prostate epithelial cells under the renal capsule.

METHODS

Vascular endothelial cells were isolated from mice and co-inoculated under the renal capsule with a prostate luminal or basal epithelial cell line. After 60 days, kidneys were examined for growth of prostate tissue. Prostatic tissues were examined by immunohistochemistry for expression of cytokeratins 5 and 8, and vascular density was determined. To determine if increased expression of VEGF-A would increase prostatic growth, transfected endothelial cells overexpressing VEGF-A were co-inoculated with the prostate luminal or basal epithelial lines.

RESULTS

Co-inoculation of endothelial cells and prostate luminal or basal epithelial cells resulted in significant growth of prostatic tissue, whereas inoculation of any of the cell lines alone resulted in little growth. The growths from co-inoculation of endothelial cells and luminal epithelial cells contained duct-like structures that stained with antibodies to cytokeratin 8, whereas those from co-inoculation of endothelial cells and basal epithelial cells contained cords of cells that stained with antibodies to cytokeratin 5. Overexpression of VEGF-A had no effect on growth of the prostatic tissues.

CONCLUSION

Endothelial cells contribute to the growth of prostatic epithelial cells.

A neutralizing anti-fibroblast growth factor (FGF) 8 monoclonal antibody shows anti-tumor activity against FGF8b-expressing LNCaP xenografts in androgen-dependent and -independent conditions

BACKGROUND

Fibroblast growth factor 8-isoform b (FGF8b) has been detected in human clinical sex-organ related cancers including hormone-refractory prostate cancer. There are, however, few relevant experimental models. A murine monoclonal anti-FGF8 antibody, KM1334, has been shown to neutralize FGF8b and inhibit the growth of androgen-dependent mouse mammary SC-3 cells in vitro and in vivo. In the present study, we evaluated the anti-tumor activity of KM1334 against androgen-dependent and -independent progression of FGF8b-expressing human prostate cancer xenografts.

METHODS

FGF8b cDNA was transfected into androgen-dependent human prostate cancer cell line LNCaP, and its xenograft tumors were established subcutaneously in SCID mice with or without castration. KM1334 at the dose of 400 microg/head was injected twice weekly.

RESULTS

FGF8b-expressing LNCaP cells secreted FGF8b, showed enhanced level of Erk1/2 phosphorylation, and showed more potent growth properties than mock-expressing cells in vitro and in vivo. KM1334 reduced these properties in vitro, inhibited tumorigenecity in vivo (T/C=0.33), and showed anti-tumor activity against established tumors (T/C=0.47) of FGF8b-expressing cells. FGF8b-expressing LNCaP tumors were androgen-dependent. However, they recurred as androgen-independent FGF8b positive tumors after castration. KM1334 also inhibited the growth of established FGF8b-expressing tumors in the androgen-independent states (T/C=0.47).

CONCLUSIONS

These results indicate that humanized monoclonal antibodies, conserving the paratope of KM1334, are a promising candidate for therapy of FGF8b-expressing clinical prostate cancers. Follow-up studies using xenograft models with clinical FGF8b-expressing tumors are required to validate these early findings.

Hypoxia expression in radiation-induced late rectal injury

Tumor hypoxia and angiogenesis have been studied extensively. However, the relation between normal tissue injury and hypoxia is still unclear. In this study, we investigated the effect of hypoxia on radiation-induced late rectal injury in mice. The rectum of C57BL/6N mice was irradiated locally with a single dose of 25 Gy and the following experiments were performed including hematoxylin-eosin (H. E.) staining, azan staining, real-time PCR, immunohistochemistry and immunofluorescene. Radiation-induced fibrotic changes were observed from 14 days and reached the peak 30 days after irradiation. The expression of transforming growth factor beta1 (TGF-beta1), hypoxia-inducible factor-1alpha (HIF-1alpha), vascular endothelial growth factor (VEGF) and endothelial cell marker CD31 increased significantly with the formation of fibrosis induced by irradiation compared with unirradiated control. In addition, the maximum expression of TGF-beta1, HIF-1alpha and VEGF was found at 14, 30 and 90 days after irradiation, respectively. The temporal changes of cytokines were consistent with the dynamic change of fibrosis. Our data suggests that late normal tissue injury involved various cytokines including hypoxia-induced angiogenic cytokines. These results may have important implications in the understanding of radiation-induced late normal tissue injury.

Altered expression of genes regulating angiogenesis in experimental androgen-independent prostate cancer

BACKGROUND

The aim of this study was to investigate how the expression of genes regulating angiogenesis is altered when prostate cancer cells progress into androgen-independency.

METHODS

A gene array specific for angiogenesis was used to compare the human prostate cancer cell line LNCaP (androgen-dependent) with its more angiogenic and tumorigenic subline LNCaP-19 (androgen-independent). Results were verified with real-time RT-PCR, and further investigations were focused on the angiogenesis inhibitor a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1). Expression of ADAMTS1 was investigated in vitro as well as in subcutaneous tumors with real-time RT-PCR and Western blotting. Microvessel density (MVD), versican proteolysis and protein levels of TIMP-2 and TIMP-3, known as ADAMTS1 inhibitors, were also analyzed in tumor xenografts.

RESULTS

The gene array revealed decreased expression of ADAMTS1, ephrin-A5, fibronectin 1, and neuropilin 1 in LNCaP-19 compared to LNCaP, while expression of midkine and VEGF were increased. Further studies showed that mRNA and protein levels of ADAMTS1 were significantly lower in LNCaP-19 compared to LNCaP, both in vitro and in subcutaneous tumors. The amount of ADAMTS1 correlated negatively with MVD, but no relation was found between ADAMTS1 and versican proteolysis.

CONCLUSIONS

Expression of several genes associated with angiogenesis was altered during transition into androgen-independency. Among these, a significant decrease was found for ADAMTS1, whose expression inversely correlated with MVD. Its role in progression of prostate cancer needs further investigation, but this inhibitor of angiogenesis could be an interesting candidate for future anti-angiogenic therapy.

Vascular density is highest in the proximal region of the mouse prostate

BACKGROUND

The proximal region of the prostatic ducts harbor the prostatic epithelial stem cells. As stem cell niches in other organs are highly vascularized, we determined if the proximal region is more highly vascularized than the remaining regions of the prostate. The effect of androgen on vascular density in the different prostatic regions was also examined.

METHODS

Sections from prostates were immunostained with antibodies to CD31, and the vascular density in proximal, intermediate, and distal regions was calculated by image analysis software. Vascular density was compared in prostates from castrated mice that received daily inoculations of testosterone or vehicle alone for 3 days. To examine the role of angiogenic factors in the response to androgen, some animals were also treated with soluble VEGF receptor-2-Fc or Tie-2--Fc fusion proteins, which inhibit the activities of VEGF and angiopoietins, respectively. The endothelial proliferative response to androgen was determined by double staining sections with antibodies to CD31 and Ki-67.

RESULTS

In prostates from intact mice, vascular density was highest in the proximal region and lowest in the distal region. Administration of testosterone to castrated mice increased vascular density to the greatest extent in the distal and intermediate regions. The increase in vascular density required VEGF and the angiopoietins. Endothelial cell proliferation was less sensitive to androgen in the proximal region than the remainder of the prostate.

CONCLUSIONS

Vascular density is highest in the proximal region of the prostate, but the proximal vessels are less responsive to testosterone.