Thomas Nelius

Characterization of PEDF: a multi-functional serpin family protein.

Pigment epithelium‐derived factor (PEDF) is a 50 kDa secreted glycoprotein that belongs to the non‐inhibitory serpin family group. PEDF has been described as a natural angiogenesis inhibitor with neurotrophic and immune‐modulation properties; it balances angiogenesis in the eye and blocks tumor progression. The mechanisms underlying most of these events are not completely clear; however, it appears that PEDF acts via multiple high affinity ligands and cell receptors. In this review article, we will summarize the current knowledge on the biochemical properties of PEDF and its receptors, the multimodal activities of PEDF and finally address the therapeutic potential of PEDF in treating angiogenesis‐, neurodegeneration‐ and inflammation‐related diseases. J. Cell. Biochem. 106: 769–775, 2009.

Clinical outcome of patients with docetaxel-resistant hormone-refractory prostate cancer treated with second-line cyclophosphamide-based metronomic chemotherapy

For patients with docetaxel-resistant hormone-refractory prostate cancer (HRPC) no standard chemotherapeutic treatment exists. In this study, we evaluate the efficacy of cyclophosphamide (CP)-based metronomic chemotherapy in this patient population. Patients with metastatic HRPC with disease progression under docetaxel-based chemotherapy were eligible. The primary endpoint was prostate-specific antigen (PSA) response. Secondary endpoints were survival and toxicity. Low-dose CP (50xa0mg/d) and dexamethasone (1xa0mg/d) were administered orally in a metronomic manner. Treatment was continued until disease progression or intolerable side effects occurred. Seventeen patients were enrolled in this study. The median follow-up was 12xa0weeks (range: 4–60). Median age was 68xa0years (range: 42–85). Median PSA at study entry was 134xa0ng/ml (range: 46.0–6554). Nine patients had a PSA response (median 44.4%), four patients ≥50% and five patients <50%. Eight patients had a PSA progression. Overall survival was 24 months. Five patients reported a decrease in bone pain after 4xa0weeks treatment. No grade 3 and 4 toxicities were noted. In this study, low-dose metronomically administered CP demonstrated efficacy as a second-line treatment in patients with docetaxel-resistant HRPC. The treatment was well tolerated and almost without toxicity. Further advantages of low-dose CP were its convenient oral administration, dosing schedule, low cost, and low-toxicity profile. These attributes in combination with immunoregulatory and antiangiogenic potentials make CP also a prime candidate for combination with other treatment regimens.

PEDF inhibits IL8 production in prostate cancer cells through PEDF receptor/phospholipase A2 and regulation of NFκB and PPARγ.

Interleukin-8 (IL8/CXCL8) has been described as a key effector in prostate cancer progression and resistance to standard chemotherapeutic drugs. In the present study, we investigated the effect of the natural, angio-inhibitory and anti-tumoral Pigment Epithelium-Derived Factor (PEDF) on the expression of IL8 cytokine by prostate cancer cells. Using a cytokine antibody array and ELISA, in addition to IL8 quantitative RT PCR, we showed that PEDF inhibits the production of IL8 in human hormone-refractory prostate cancer cells, and delays the growth of these cells in vitro. IL8 reduction was mimicked in cancer cells treated with PPARγ agonist and NFκB-specific inhibitors. Accordingly, PPARγ expression increased in response to PEDF, whereas RelA/p65 expression and nuclear localization, and NFκB transcriptional activity decreased. NFκB deactivation was reversed by the PPARγ antagonist GW9662 and PPARγ (Leu(468)/Glu(471)) dominant negative suggesting a PPARγ-dependent process. We also investigated PEDF Receptor/PLA2 as key player in this pathway by small interference RNA. PEDFR knock down in prostate cancer cells reversed PEDF-induced PPARγ up-regulation, and NFκB and IL8 inhibition compared to non-targeting control siRNA. We conclude that by binding to PEDFR, PEDF up-regulates PPARγ, leading subsequently to suppressed NFκB-mediated transcriptional activation, reduced production of IL8 and limited proliferation of prostate cancer cells. These results reinforce PEDFs therapeutic potential and imply that blocking IL8 could represent a novel alternative for prostate cancer treatment.

Androgen receptor targets NFκB and TSP1 to suppress prostate tumor growth in vivo

The androgen role in the maintenance of prostate epithelium is subject to conflicting opinions. While androgen ablation drives the regression of normal and cancerous prostate, testosterone may cause both proliferation and apoptosis. Several investigators note decreased proliferation and stronger response to chemotherapy of the prostate cancer cells stably expressing androgen receptor (AR), however no mechanistic explanation was offered. In this paper we demonstrate in vivo anti‐tumor effect of the AR on prostate cancer growth and identify its molecular mediators. We analyzed the effect of AR on the tumorigenicity of prostate cancer cells. Unexpectedly, the AR‐expressing cells formed tumors in male mice at a much lower rate than the AR‐negative controls. Moreover, the AR‐expressing tumors showed decreased vascularity and massive apoptosis. AR expression lowered the angiogenic potential of cancer cells, by increasing secretion of an anti‐angiogenic protein, thrombospondin‐1. AR activation caused a decrease in RelA, a subunit of the pro‐survival transcription factor NFκB, reduced its nuclear localization and transcriptional activity. This, in turn, diminished the expression of its anti‐apoptotic targets, Bcl‐2 and IL‐6. Increased apoptosis within AR‐expressing tumors was likely due to the NFκB suppression, since it was restricted to the cells lacking nuclear (active) NFκB. Thus we for the first time identified combined decrease of NFκB and increased TSP1 as molecular events underlying the AR anti‐tumor activity in vivo. Our data indicate that intermittent androgen ablation is preferable to continuous withdrawal, a standard treatment for early‐stage prostate cancer.

PSA surge/flare-up in patients with castration-refractory prostate cancer during the initial phase of chemotherapy

Docetaxel‐based chemotherapy has shown great promise for the treatment of CRPC and is considered the current standard of care. PSA is mainly used as marker to monitor the treatment response. Several articles were published reporting an initial PSA surge/flare‐up after starting chemotherapy. The cause and the impact of this phenomenon are discussed controversially. The intention of this review is to define the significance of initial PSA surge/flare‐up and to increase awareness to this phenomenon in the urological community.

Impact of PSA flare-up in patients with hormone-refractory prostate cancer undergoing chemotherapy

ObjectivesThe intention of this study is to describe the impact and underlying potential basis of the prostate-specific antigen (PSA) flare-up phenomenon in patients with hormone-refractory prostate cancer (HRPC) treated with docetaxel-based chemotherapy.MethodsWe retrospectively identified 74 consecutive patients who received docetaxel/estramustine-based chemotherapy at our institution. Patients were evaluated based on modified criteria from the Prostate-Specific Antigen Working Group regarding survival and toxicity. Additionally, two androgen receptor mutations derived from patients with advanced disease were analyzed for promiscuous transactivation activity.ResultsThe 74 patients were stratified into four groups: response, partial response, flare-up-initial PSA elevation, and progression. Median survival in the flare-up group (nxa0=xa08) was 20xa0months and did not differ from the response group (pxa0=xa00.564). The flare-up group showed a maximum PSA elevation from baseline between 3.4 and 28.3% (between three and sixxa0weeks) followed by PSA decline ≥50% from the baseline level in seven of the eight patients. The androgen receptor mutations AR877 and AR715 displayed a 37.5- and 5.2-fold increase in transactivation activity by progesterone and a 12.6- and 5.4-fold increase by estrogen compared to the ARWT, respectively.ConclusionsA considerable portion of HRPC patients experience an initial PSA flare-up under systemic chemotherapy. In this study, occurence of flare-up phenomenon did not impact survival. Chemotherapy should be continued a minimum of sixxa0weeks before removing patients from a docetaxel-based regimen. We showed evidence that co-medication with dexamethasone/prednisolone and/or estramustine itself can induce an initial PSA flare-up via androgen receptor mutations.

Oral/metronomic cyclophosphamide-based chemotherapy as option for patients with castration-refractory prostate cancer - Review of the literature

PURPOSEnCastration-refractory prostate cancer remains a therapeutic challenge even after introduction of docetaxel as first-line treatment. Castration-refractory prostate cancer cannot be cured by any available therapeutic option, and chemotherapy still needs to be considered palliative. The survival benefit is modest, and treating physicians are searching for alternative treatment options. Despite new drugs currently under investigation, some conventional and well known chemotherapeutic drugs are experiencing a renaissance. The development of anti-angiogenic approaches in cancer treatment has led to the development of metronomic dosing of conventional chemotherapeutic drugs including cyclophosphamide. The intention of this review is to evaluate the efficacy and toxicity of oral/metronomic cyclophosphamide in the treatment of patients with castration-refractory prostate cancer.nnnMATERIALS AND METHODSnA comprehensive literature search was performed in different databases using various key words. Relevant articles and references between 1962 and 2010 were reviewed and analyzed for data regarding the association between oral cyclophosphamide treatment and prostate cancer.nnnRESULTSnOral cyclophosphamide is active in the treatment for castration-refractory prostate cancer even in patients treated with previous chemotherapy including docetaxel. It yields symptomatic and objective remissions. The side effects are usually grade 1-2 and easy to manage. Grade three to four side effects are less common.nnnCONCLUSIONSnOral cyclophosphamide treatment for patients with castration-refractory prostate cancer deserves more attention and validation, and warrants further testing of various treatment combinations. Given the fact that castration-refractory prostate cancer includes an extremely heterogeneous group of patients with variability of tumor growth rates, the combination of cyclophosphamide with other active agents such as angiogenesis inhibitors and immunomodulatory compounds need to be explored.

Cross-sectional Study Examining Four Types of Male Penile and Urethral “Play”

OBJECTIVESnTo provide further quantitative and qualitative evidence about men who insert foreign liquids and objects into their penis and/or urethra.nnnMETHODSnAs part of a larger, cross-sectional study examining men (n = 445) with genital piercings (GP), 2 questions inquired whether the respondents had penile tattoos and/or inserted other materials, such as fluids and foreign objects, into their penis and urethra.nnnRESULTSnFour different practices have been described in the literature: embedding (a) foreign objects and/or (b) liquids subcutaneously into penile tissue, as well as inserting (c) liquids and/or (d) foreign objects into the urethra. In our study, 354 (78%) men with GP responded to the 2 questions; 85 (24%) replied affirmatively and 68 (80%) provided comments. Respondents coined their practices penile and/or urethral play. Two respondents embedded metal balls into their penis, 1 at age 13 injected water for penis enlargement; 11 inserted liquids into the urethra, and 63 reported insertion of 32 different objects, frequently urethral sounds or sounding (n = 33/52%) were mentioned. Major motivation themes focused on sexual stimulation and experimentation. Penile tattoos (n = 14) were also reported, mainly for esthetics. Few complications or STDs were reported.nnnCONCLUSIONSnBasic demographic assumptions of those who participate in these actions were challenged, and this study provides evidence of a wider distribution of men using penile or urethral play, and sounding. Clinician awareness of these practices are important to obtain accurate health histories, manage genitourinary tract complications, as well as provide applicable patient education.

INTS6/DICE1 inhibits growth of human androgen-independent prostate cancer cells by altering the cell cycle profile and Wnt signaling

BackgroundThe gene encoding integrator complex subunit 6 (INTS6), previously known as deleted in cancer cells 1 (DICE1, OMIM 604331) was found to be frequently affected by allelic deletion and promoter hypermethylation in prostate cancer specimens and cell lines. A missense mutation has been detected in prostate cancer cell line LNCaP. Together, these results suggest INTS6/DICE1 as a putative tumor suppressor gene in prostate cancer. In this study, we examined the growth inhibitory effects of INTS6/DICE1 on prostate cancer cells.ResultsMarkedly decreased INTS6/DICE1 mRNA levels were detected in prostate cancer cell lines LNCaP, DU145 and PC3 as well as CPTX1532 as compared to a cell line derived from normal prostate tissue, NPTX1532. Exogenous re-expression of INTS6/DICE1 cDNA in androgen-independent PC3 and DU145 cell lines substantially suppressed their ability to form colonies in vitro. This growth inhibition was not due to immediate induction of apoptosis. Rather, prostate cancer cells arrested in G1 phase of the cell cycle. Expression profiling of members of the Wnt signaling pathway revealed up-regulation of several genes including disheveled inhibitor CXXC finger 4 (CXXC4), frizzled homologue 7 (FZD7), transcription factor 7-like 1 (TCF7L1), and down-regulation of cyclin D1.ConclusionThese results show for the first time a link between INTS6/DICE1 function, cell cycle regulation and cell-cell communication involving members of the Wnt signaling pathway.

Positive correlation between PEDF expression levels and macrophage density in the human prostate.

In this study, we investigated the capacity of pigment epithelium‐derived factor (PEDF) to modulate the recruitment and the differentiation of monocytes/macrophages both in vitro and in human prostate.