Regulation of aromatase expression: Potential therapeutic insight into breast cancer treatment

Estrogen signaling has been implicated in hormone-dependent breast cancer which constitutes >75% of breast cancer diagnosis and other malignancies. Aromatase, the key enzyme involved in the synthesis of estrogen, is often dysregulated in breast cancers. This has led to the administration of aromatase-inhibitors (AIs), commonly used for hormone-dependent breast cancers. Unfortunately, the increasing development of acquired resistance to the current AIs and modulators of estrogen receptors, following initial disease steadiness, has posed a serious clinical challenge in breast cancer treatment. In this review we highlight historical and recent advances on the transcriptional and post-translational regulation of aromatase in both physiological and pathological contexts. We also discuss the different drug combinations targeting various tumor promoting cell signaling pathways currently being developed and tested both in laboratory settings and in the clinic.

Effect of Serum Deprivation Stress on Signal Induction Regulatory Protein-Alpha (SIRP-Alpha)-Mediated Erythrophagocytosis by Macrophages

BACKGROUND Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome that involves loss of macrophages' self-cells recognition resulting in auto-phagocytosis of erythrocytes, leukocytes, and platelets and leading to multi-system effects. The pathogenesis of HLH is unclear but can be explained by malfunction of the physiologic inhibitory pathway through interaction between macrophage SIRP-alpha and erythrocyte CD 47. The goal of the present study was to evaluate if erythrocytes phagocytosis occurs as a result of altered macrophage SIRP-alpha expression during inflammatory/stressful conditions as seen in HLH. MATERIAL AND METHODS RAW264.7 macrophages were cultured in serum-free media (SFM) and complete media (CM) to simulate stressful and physiologic conditions, respectively. CD47+ mouse erythrocytes were used to test interactions with macrophages at different stages. SIRP-alpha expressions and phagocytosis assays were measured and analyzed at different steps. The study was in vitro and used murine cells to simulate in vivo human interactions. RESULTS SIRP-alpha expressions and phagocytosis rates were higher in SFM compared to CM. Interestingly, after adding SIRP-alpha blocking antibodies (Ab), phagocytosis rates significantly decreased. CONCLUSIONS Serum deprivation and LPS/INF-Gamma induction resulted in increased SIRP-alpha expression and erythrophagocytosis. Using SIRP-alpha Ab during this condition decreased the rate of erythrophagocytosis, which indicates that SIRP-alpha receptor can have pro-phagocytic activity.

Pre-metastatic cancer exosomes induce immune surveillance by patrolling monocytes at the metastatic niche

Metastatic cancers produce exosomes that condition pre-metastatic niches in remote microenvironments to favor metastasis. In contrast, here we show that exosomes from poorly metastatic melanoma cells can potently inhibit metastasis to the lung. These "non-metastatic" exosomes stimulate an innate immune response through the expansion of Ly6Clow patrolling monocytes (PMo) in the bone marrow, which then cause cancer cell clearance at the pre-metastatic niche, via the recruitment of NK cells and TRAIL-dependent killing of melanoma cells by macrophages. These events require the induction of the Nr4a1 transcription factor and are dependent on pigment epithelium-derived factor (PEDF) on the outer surface of exosomes. Importantly, exosomes isolated from patients with non-metastatic primary melanomas have a similar ability to suppress lung metastasis. This study thus demonstrates that pre-metastatic tumors produce exosomes, which elicit a broad range of PMo-reliant innate immune responses via trigger(s) of immune surveillance, causing cancer cell clearance at the pre-metastatic niche.

Understanding docetaxel and cabazitaxel modes of action in prostate cancer

e23149

Background: Despite the approval of several new agents, taxanes remains the main treatment with survival benefits for castration-refractory metastatic prostate cancer/mCRPC. Still their mechanisms of action and therapeutic efficacy remain incompletely characterized. In the present study, we proposed to compare docetaxel/Doc and cabazitaxel/Cab, delivered as monotherapy or in combination with the anti-angiogenic and anti-tumoral Pigment Epithelium-Derived Factor/PEDF, on CRPC cells in vitro and in vivo. Methods: CRPCcells were assessed for cell growth, cell cycle, and apoptosis under taxane/control treatment by cytotoxicity, PI incorporation and TUNEL assays. CL1 cells that express PEDF/control were used in vivo. Tumor cells were injected s.c. into CB17-SCID mice. After two weeks, mice were randomized into groups: 1) Placebo; 2) Doc 5mg/kg i.p. d4; and 3) Cab 5-1-0.5-0.1mg/kg i.p. d4, d1-7, d2, daily. To assess the anti-tumor effect of the combination, tumor cell migration and phagocytosis were measured by Boyden chamber and confocal microscopy analyses of CL1-RAW264.7 macrophages co-cultures. Results: Cab was more cytotoxic than Doc in all the cell lines tested.This effect was concomitant to increased cell death, but was not due to autophagy or necrosis. Inversely, we showed that apoptosis was superior in Cab-treated cells than in Doc treatment. In vivo, while 0.5 and 0.1 mg/kg Cab did not improve PEDF efficacy on tumor growth, 1mg/kg was very toxic. In contrast, PEDF combined with 5mg/kg Cab lead to stabilization of the disease and was also found to be drastically more efficient than PEDF/Doc in delaying the disease. In vitro, PEDF/Cab inhibited tumor cell migration at a significant superior level compared to PEDF/Doc. Finally, tumor cells phagocytosis was induced in PEDF/Cab suggesting that the combination may target macrophages within the tumor microenvironment. Conclusions: Our data demonstrated the greater anti-tumor efficacy of Cab compared to Doc. They also insist on the fact that PEDF/Cab could be used as a novel combined therapy for CRPC, and emphasize on the importance in evaluating the cytotoxicity of the novel combination tested and investigating the role of the tumor microenvironment in the anti-tumor effect.

Modes of action of low-dose cabazitaxel in combination with the antiangiogenic and antitumoral pigment epithelium-derived factor in prostate cancer

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Background: Despite the approval of several new agents, taxanes remain the main alternative treatment for castration-refractory metastatic prostate cancer (mCRPC). In a previous work, we have demonstrated that cabazitaxel is more efficient in a low-dose setting than docetaxel in inhibiting the proliferation and inducing apoptosis of CRPC cells in vitro, and delaying tumor growth in vivo. In the present study, we have investigated the efficacy of low-dose cabazitaxel when combined with the anti-angiogenic and anti-tumoral Pigment Epithelium-Derived Factor (PEDF). Methods: CRPC CL1 cells (LNCaP-derivative) that express PEDF or control plasmid were used. Tumor cells were injected s.c. into C.B.17-SCID mice. After two weeks, mice were randomized into groups: 1) Placebo; 2) Docetaxel: 5mg/kg i.p. d4; and 3) Cabazitazel 5-1-0.5-0.1mg/kg i.p. d4, d1-7, d2, and daily. To investigate the molecular mechanisms involved in the anti-tumor effect of the combined treatment, tumor cell migration was measured using the inverted Boyden chamber assay. Tumor cell phagocytosis was also assessed in CL1-RAW264.7 macrophages co-cultures. Results: We showed that while 0.5 and 0.1 mg/kg cabazitaxel did not improve PEDF efficacy on tumor growth, 1mg/kg was extremely toxic, killing 1/2 animals within the first week of treatment. In contrast, we demonstrated that PEDF combined with 5mg/kg cabazitaxel lead to stabilization of the disease. PEDF/cabazitaxel was also found to be drastically more efficient than PEDF/docetaxel in delaying the disease. In vitro, PEDF/cabazitaxel inhibited tumor cell migration at a superior level compared to PEDF/docetaxel. Finally, PEDF/cabazitaxel induced more phagocytosis of the tumor cells by macrophages than PEDF/docetaxel suggesting that the combination may target macrophages within the tumor microenvironment. Conclusions: Our data demonstrated that PEDF with low-dose cabazitaxel could be used as a novel therapeutic combination to treat CRPC. Our results also emphasize on the importance in closely evaluating the cytotoxicity of the combination tested and investigating the role of the tumor microenvironment in the anti-tumor effect.

Comparison of docetaxel and cabazitaxel efficacy on prostate cancer cells both in vitro and in vivo

351

Background: Despite recently approved novel agents, taxane-based chemotherapy remains the major therapeutic strategy for metastatic castration-refractory prostate cancer/mCRPC. Still mCRPC continues to be incurable. Besides, patients often experience severe side effects, prompting a re-evaluation of standard regimen. Past studies have demonstrated promise for Low-Dose Metronomic/LDM chemotherapy, defined as the frequent administration of low doses of chemotherapeutic drugs with no prolonged drug-free breaks. Yet relative activities of LDM taxanes and combinations with known anti-neoplasic agents have to be investigated. Methods: PC3, Du145 and LNCaP-derivative CL1cell lines were used to compare the effect of increasing doses of taxanes on cell proliferation, cell cycle distribution and apoptosis by crystal violet, propidium iodide and AnnexinV stainings, respectively. Autophagy was assessed by western blotting against Beclin1. In vivotumor growth was measured using CL1 control and CL1-PEDF xenografts. Phagocytosis was determined by cytotoxicity assay in CL1-macrophages co-cultures. Results: Our data showed that cabazitaxel/cbz-treated cells had a significantly lower EC50 compared to docetaxel/doc, with Du145 cells presenting the greatest differences. Both low-dose taxanes increased the sub-G0 cells population. However, the sub-G0 increase was significantly greater in cbz- than doc-treated Du145 cells, but not in PC3 and CL1. Accordingly, plasma membrane Annexin V elevation occurred in Du145 cells at lower doses of cbz than doc validating a higher efficacy due to increased apoptosis. Although Beclin1 levels remain unchanged in PC3 and CL1 cells, it was found up-regulated for all doses of cbz in Du145. In vivo, LDM cbz was significantly more efficient in curbing tumor growth than doc. This effect was markedly increased when cbz was combined with the angio-inhibitor and anti-tumor Pigment Epithelium-Derived Factor (PEDF); an effect that could be explained by increased phagocytosis. Conclusions: Our data demonstrate a higher efficacy of cbz on CRPC both in vitro and in vivo, and suggest that LDM taxane chemotherapy/PEDF combination could be used as a novel therapeutic strategy for CRPC.

Abstract 3359: PEDF modulatory action on macrophages: A new way to curb prostate cancer development

Macrophages have been described as one of the main inflammatory components involved in prostate cancer (PCa) initiation, progression, and metastasis. PEDF (Pigment Epithelium-Derived Factor) is an anti-angiogenic factor with differentiation activities and was recently suggested as an immune-modulating factor. PEDF expression has been shown to be down-regulated in PCa compared to normal tissues. In previous studies we have demonstrated that PEDF re-expression in PCa cells curbs tumor growth in vivo and significantly prolongs the survival of tumor-bearing mice. Others have shown that PEDF expression increased the recruitment of tumor-cytotoxic macrophages into orthotopic MatLyLu rat prostate tumors suggesting a link between PEDF and inflammation in PCa. While PEDF's role in inflammation has been suggested, the precise modes of action of PEDF on macrophages still remain unknown and necessitate further investigation. Our preliminary data have showed that PEDF stimulates the migration of monocytes/macrophages using in vitro chemotaxis boyden chamber assay and towards tumor 3D spheroids. We showed that PEDF expression levels positively correlate with macrophage density in human prostate. In both cell lines and prostate specimens, we have demonstrated that PEDF directly induces the polarization of macrophages and bone marrow derived macrophages (BMDMs) towards a M1/tumor-cytotoxic pathway. As a result of their differentiation, we have found that PEDF stimulates the phagocytosis of tumor cells, which suggest another mechanism by which PCa growth is halted. We are currently investigating the molecular mechanisms by which PEDF induces migration, differentiation and phagocytic activity in macrophages. PEDF mechanisms are being investigated by expression levels of PEDF receptors (ATP5B, PNPLA2, LRP6) in macrophage cell lines and BMDMs. So far we have been identified ATP5B and PNPLA2 as the two main receptors expressed in both cell types. While all three receptors in cell lines increased, only ATP5B and PNPLA2 receptors increased in BMDMs in response to PEDF. To map the functional region involved in PEDF's inflammatory action, we are investigating the PEDF-derivative synthetic 18-mer peptide (residues 39-57). P18 has been shown to block endothelial cell chemotaxis and induces apoptosis in vitro, and to be more effective than its parental 34-mer peptide (residues 24-57) in blocking growth and angiogenesis in PCa. We were able to demonstrate that macrophages treated with P18 in comparison to PEDF, show a higher efficacy for macrophages differentiation. Using confocal microscopy we demonstrated a larger rate of phagocytosis of PCa cells by macrophages than compared to PEDF. The results of our study are of importance as they suggest that macrophages may play a key role in PEDF anti-tumor effects. A better understanding of PEDF may lead to further development of PEDF-based anticancer therapy or improvement of alternatives to chemotherapy for PCa.

Citation Format: Dalia Martinez-Marin, Thomas Nelius, Olga Volpert, Stephanie Filleur. PEDF modulatory action on macrophages: A new way to curb prostate cancer development. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3359. doi:10.1158/1538-7445.AM2015-3359

Effect of cabazitaxel on the growth of human castration-refractory prostate cancer cells in vitro compared to docetaxel and on the anti-tumor properties of the angio-inhibitor PEDF in vivo

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Background: Docetaxel/DTX and cabazitaxel/CBZ have shown promise in the treatment of metastatic Castration-Refractory Prostate Cancer/mCPRC however, comparative studies are missing. Toxicities of these drugs are significant, urging the need to modify taxane regimens. Recently, low-dose metronomic/LDM treatments using conventional chemotherapeutic drugs have shown benefits in CPRC in improving the effect of anti-angiogenic agents. Previously, we have demonstrated that LDM-DTX in combination with PEDF curbs significantly CRPC growth, limits metastases formation and prolongs survival in vivo. In this study, we intended to compare the cytotoxic effect of CBZ and DTX on CRPC cells in vitro and CL1 tumors in vivo. Methods: PC3, DU145 cell lines were from ATCC.CL1 cells were obtained from androgen-deprived LNCaP cells. Cell proliferation was assessed by crystal violet staining and cell cycle analyses. In vitro cytotoxicity assays were performed on CL1 cells/RAW264.7 macrophages co-cultures treated with PEDF and increasing doses of taxanes. For the in vivo studies, CL1 cells were engineered to stably express the DsRed Express protein +/- PEDF. PEDF anti-tumor effects were assessed on s.c. xenografts treated with DTX (5mg/kg ip ev. 4 day) as reference, CBZ (5mg/kg ip ev. 4 days, 1mg/kg for 10 days, 0.5mg/kg q.a.d. and 0.1mg/kg daily) or placebo. Results: CBZ limits cell proliferation with a greater efficacy than DTX in all CRPC cell lines tested. DU145 presented the largest difference. High doses of taxane blocked tumor cells in mitosis, whereas LDM increased the SubG1 population. This effect was significantly higher in DU145 cells treated with CBZ. In vivo, 5mg/kg CBZ delayed tumor growth more efficiently than 5mg/kg DTX. PEDF/5mg/kg CBZ markedly delayed tumor growth compared to all treatments. Finally, engulfment of tumor cells by macrophages was higher in combined treatments suggesting an inflammation-related process. Conclusions: CBZ is more efficient than DTX both in vitro and in vivo.The data also reinforce PEDF as a promising anti-neoplasic agent in combination with LDM taxane chemotherapies.

Vacuolar H+-ATPase is down-regulated by the angiogenesis-inhibitory pigment epithelium-derived factor in metastatic prostate cancer cells

The Vacuolar H+-ATPases (V-ATPases), a multi-subunits nanomotor present in all eukaryotic cells resides in the endomembranes of exocytotic and endocytotic pathways. Plasmalemmal V-ATPases have been shown to be involved in tumor cell metastasis. Pigment epithelium-derived factor (PEDF), a potent endogenous inhibitor of angiogenesis, is down-regulated in prostate cancer cells. We hypothesized that the transduction of PEDF in prostate cancer cells will down-regulate V-ATPase function; that in turn will decrease the expression of the V-ATPase accessory protein ATP6ap2 and a-subunit isoforms that target V-ATPase to the cell surface. To test these hypotheses, we used the human androgen-sensitive prostate cancer cells LNCaP, and its castration-refractory-derivative CL1 that were engineered to stably co-express the DsRed Express Fluorescent Protein with or without PEDF. To determine if PEDF down-regulates the function of V-ATPase, we measured the rate of proton fluxes (JH+) of the cytosolic and endosome/lysosome compartments. The mRNA levels for subunit-a isoforms and the ATP6ap2 were measured using quantitative reverse transcription-PCR. The results showed that PEDF expression decreased the rate of JH+ in metastatic CL1 cells without affecting JH+ in non-metastatic LNCaP cells, when studying pH(cyt). Interestingly, PEDF did not affect JH+ in endosomes/lysosomes either in metastatic cells or in non-metastatic cells. We also showed that PEDF significantly decreases the levels of a4 isoform and ATP6ap2 in metastatic CL1 cells, without affecting the levels of a4 isoform in the non-metastatic LNCaP cells. These data identify PEDF as a novel regulator of V-ATPase suggesting a new way by which PEDF may inhibit prostate tumor growth.

Pigment epithelium-derived factor expression prolongs survival and enhances the cytotoxicity of low-dose chemotherapy in castration-refractory prostate cancer

There is currently no cure for advanced castration-refractory prostate cancer (CRPC) despite the recent approval of several new therapeutic agents. We report here the anti-tumor effect of the angio-inhibitory pigment epithelium-derived factor (PEDF) in the metastatic LNCaP-derivative CRPC CL1 model and explore PEDF anti-neoplasic efficacy in combination with low-dose chemotherapy. Androgen-sensitive LNCaP and CRPC PC3 cell lines were examined as comparison. Using a retroviral expression system, we showed that PEDF limited the proliferation of all prostatic cell lines tested; an effect attributed to interleukin 8 (IL8)-CXCR1/IL8RA inhibition. PEDF also reduced the number and size of 3D tumor spheroids in vitro, but only induced cell differentiation in CRPC spheroids. Similarly, PEDF inhibited the migration of CRPC cells suggesting both anti-proliferative and anti-migratory functions. In vivo, PEDF decreased by 85% and 65% the growth of subcutaneous (s.c.) PC3 and CL1 tumors, respectively. In the CL1 orthotopic model, tumor intake with lethal metastases was found in all animals; nevertheless, PEDF prolonged the median survival of tumor-bearing mice (95% confidence interval: 53±0.001 to 57±1 days). Accordingly, PEDF delayed the emergence of skeletal-related event in intra-tibial xenografts. Next, we evaluated low-dose docetaxel (DTX; 5, 1, 0.5 mg/kg) or cyclophosphamide (CTX; 10–20 mg/kg) on established s.c. PC3 tumors that conditionally express PEDF anti-tumoral epitope/NT3. Although NT3–DTX-5 mg/kg combination was inefficient, NT3–DTX-1 mg/kg and -0.5 mg/kg inhibited by 95% and 87.8%, respectively, tumor growth compared with control and induced tumor stasis. Both NT3–CTX combinations were advantageous. Inversely, PEDF–DTX-5 mg/kg and PEDF–CTX-10 mg/kg delayed the most CL1 tumor growth (15, 11 and 5 days for PEDF–DTX-5 mg/kg, PEDF–CTX-10 mg/kg and single treatments, respectively) with elevated apoptosis and serum thrombospondin-1 as possible mechanism and marker, respectively. As well, both PEDF–CTX-10 mg/kg and PEDF–DTX-5 mg/kg prolonged significantly the survival of tumor-bearing mice compared with single treatments. Metastases were reduced in PEDF–DTX-5 mg/kg compared with other treatments, suggesting that PEDF–DTX delayed metastases formation. Our results advocate that PEDF/low-dose chemotherapy may represent a new therapeutic alternative for CRPC.

Abstract 5097: PEDF inhibits bone metastases formation, prolongs survival and enhances the antitumor efficacy of low-dose chemotherapy in castration-refractory prostate cancer

Background: The development of metronomic/low dose administration of conventional chemotherapeutic drugs has shown great promise in the treatment of castration-refractory prostate cancer (CPRC). Pigment Epithelium-Derived Factor (PEDF) is a natural angio-inhibitor which is down-regulated in prostate cancer. We have previously demonstrated that the over-expression of PEDF in human CRPC PC3 cells decreased tumor growth in vivo. In the present study, we further validated PEDF anti-tumor properties in the highly metastatic CRPC LNCaP-derivative CL1 cells. We also hypothesized that PEDF may enhance the cytotoxicity effects of low dose docetaxel (DTX) and cyclophosphamide (CTX) chemotherapies in vivo. Methods: PC3 and CL1 cell lines were genetically modified to stably express the fluorescent DsRed Express protein with PEDF. Resulting cells were characterized in vitro for PEDF expression by western blot and, for proliferation by growth curves and clone formation in matrigel. PEDF anti-tumor effects were assessed on established s.c. xenografts in mice treated with DTX (5mg/kg ip every 4 days, 1mg/kg ip daily for 10 days, 0.5mg/kg every other day), CTX (10-20mg/kg in the drinking water) or placebo. Survival studies were performed by injecting CL1-PEDF or -control cells into the left lobe of the dorsal prostate of anesthetized mice. For bone metastases, CL1-PEDF or -control cells were injected into the proximal region of the tibia. Results: We showed that PEDF expression inhibits the proliferation and induces the differentiation of CPRC cells in vitro, and decreases by 85% and 70% the development of s.c. PC3 and CL1 tumors, respectively. In vivo, PEDF expression inhibits the formation of bone metastases and bone destruction, and prolongs significantly (P=0.01; 95% confidence interval) the median survival of CL1 tumor-bearing mice (53±0.001 days versus 57±1). Furthermore, we demonstrated that PEDF enhances the cytotoxicity effects of low dose chemotherapy on established s.c. tumors (best Doc dose: 1mg/kg for PC3 and 5mg/kg for CL1; best CTX dose: 10mg/kg for PC3 and CL1) and prolongs significantly the survival of tumor-bearing mice undergoing low dose chemotherapy. Conclusions: These data reinforce the significance of PEDF as a potent target for the treatment of CRPC. It also emphasizes PEDF as a promising new agent to enhance the anti-tumor efficacy of low dose chemotherapies.

Citation Format: Thomas Nelius, Jennifer Hirsch, Stephanie Filleur. PEDF inhibits bone metastases formation, prolongs survival and enhances the antitumor efficacy of low-dose chemotherapy in castration-refractory prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5097. doi:10.1158/1538-7445.AM2013-5097

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.

Effect of PEDF on the in vivo antitumor activities of low-dose chemotherapy in CRPC

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Background: The development of metronomic/low dose administration of conventional chemotherapeutic drugs has shown great promise in the treatment of castration-refractory prostate cancer (CPRC). Pigment Epithelium-Derived Factor (PEDF) is a natural angio-inhibitor which is down-regulated in prostate cancer. We have previously demonstrated that the over-expression of PEDF in human CRPC PC3 cells decreased tumor growth in vivo. In the present study, we further validated PEDF anti-tumor properties in the highly metastatic CRPC LNCaP-derivative CL1 cells. We also hypothesized that PEDF may enhance the cytotoxicity effects of low dose docetaxel (DTX) and cyclophosphamide (CTX) chemotherapies in vivo. Methods: PC3 and CL1 cell lines were genetically modified to stably express the fluorescent DsRed Express protein with PEDF. Resulting cells were characterized in vitro for PEDF expression by western blot and, for proliferation by growth curves and clone formation in matrigel. PEDF anti-tumor effects were assessed on established s.c. xenografts in mice treated with DTX (5mg/kg ip every 4 days, 1mg/kg ip daily for 10 days, 0.5mg/kg every other day), CTX (10-20mg/kg in the drinking water) or placebo. Survival studies were performed by injecting CL1-PEDF or -control cells into the left lobe of the dorsal prostate of anesthetized mice. Results: We showed that PEDF expression inhibits the proliferation and induces the differentiation of CPRC cells in vitro, and decreases by 85% and 70% the development of s.c. PC3 and CL1 tumors, respectively. In the survival study, PEDF expression prolongs significantly (P=0.01; 95% confidence interval) the median survival of CL1 tumor-bearing mice (53±0.001 days versus 57±1). Furthermore, we demonstrated that PEDF enhances the cytotoxicity effects of low dose chemotherapy on established s.c. tumors (best Doc dose: 1mg/kg for PC3 and 5mg/kg for CL1; best CTX dose: 10mg/kg for PC3 and CL1) and prolongs significantly the survival of tumor-bearing mice undergoing low dose chemotherapy. Conclusions: These data reinforce the significance of PEDF as a potent target for the treatment of CRPC. It also emphasizes PEDF as a promising new agent to enhance the anti-tumor efficacy of low dose chemotherapies.

The clinical usefulness of nuclear matrix protein-22 in patients with end-stage renal disease and microscopic hematuria

OBJECTIVES

To evaluate the sensitivity, specificity, and false-positive rate of the nuclear matrix protein-22 (NMP22) test in patients with end-stage renal disease (ESRD) and microscopic hematuria in order to avoid unnecessary follow-up tests for patients with false-positive NMP22 test results.

PATIENTS AND METHODS

Patients with ESRD were screened for microscopic hematuria as part of the pre-transplant workup. Patients with documented microscopic hematuria underwent workup as recommended by the American Urological Association.

RESULTS

Between January 2006 and April 2012, 277 patients with ESRD were referred to the Department of Urology for pre-transplant evaluation. Fifty-seven (22.6%) patients were found to have microscopic hematuria and underwent further testing. Nineteen (33.3%) patients demonstrated a positive NMP22 test result and 38 (66.7%) had a negative NMP22 test result. The false-positive rate was 32.7%. The sensitivity and specificity of the NMP22 test in this patient population were 50% and 67%, respectively. The positive predictive value of the test was 52.6% and the negative predictive value 97.3%. Especially noteworthy, the two detected transitional cell cancers of the urinary bladder were both demonstrated during cystoscopy, independent of their NMP22 or urine cytology test result.

CONCLUSIONS

Our study revealed a significantly increased NMP22 test false-positive rate, low sensitivity, and specificity in the setting of high prevalence of microscopic hematuria, proteinuria, and low glomerular filtration rate in patients with ESRD. Therefore, cystoscopy remains the gold standard for patients with ESRD and microscopic hematuria for pre-transplant evaluation.

Effect of PEDF on survival and in vivo antitumor activities of low-dose chemotherapy in castration-refractory prostate cancer

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Background: The development of metronomic/low-dose treatment with conventional chemotherapeutic drugs has recently shown promise in the treatment of castration-refractory prostate cancer (CPRC). Pigment Epithelium-Derived Factor (PEDF) is a natural angio-inhibitor which is downregulated in prostate cancer. Previously we demonstrated that overexpression of PEDF in human CRPC PC3 cells decreased tumor growth in vivo. In the present study, we further validate PEDF anti-tumor properties in highly metastatic CRPC LNCaP-derivative CL1 cells. We also hypothesized that PEDF may enhance the cytotoxic effects of low-dose docetaxel (Doc) and cyclophosphamide (CTX) chemotherapies in vivo. Methods: Human PC3 and CL1 cell lines were genetically modified to stably express fluorescent DsRed Express protein with PEDF. Resulting cells were characterized in vitro for PEDF expression by western blot and for proliferation by growth curves and clone formation in Matrigel. PEDF anti-tumor effects were assessed on established SC xenografts in mice treated with Doc (5mg/kg IP every 4 days, 1mg/kg IP daily for 10 days, 0.5mg/kg IP every other day), CTX (10-20mg/kg in drinking water) or placebo. Survival studies were performed by injecting CL1 cells that express PEDF or control into the left lobe of the dorsal prostate of anesthetized mice. Results: We showed that PEDF inhibits proliferation and induces differentiation of all CPRC cells tested in vitro. Similarly, PEDF expression decreases by 85% and 70% the development of SC PC3 and CL1 tumors, respectively. In the survival study, we found that PEDF expression prolongs significantly (p=0.01; 95% confidence interval) median survival of CL1 tumor-bearing mice (53±0.001 days versus 57±1). Most importantly, we demonstrated that PEDF enhances the cytotoxic effects of low-dose chemotherapy on established tumors (best Doc dose: 1mg/kg for PC3 and 5mg/kg for CL1; best CTX dose: 10mg/kg for PC3 and CL1). Conclusions: This data reinforces the significance of PEDF as a potential new target when treating advanced prostate cancer. It also emphasizes PEDF as a promising new agent to enhance the anti-tumor efficacy of low-dose Doc and CTX chemotherapies.

Abstract 3717: Pigment epithelium-derived factor prolongs survival and enhances the in vivo antitumor activities of low-dose chemotherapy in castration-refractory prostate cancer

Background: The development of metronomic/low-dose administration of conventional chemotherapeutic drugs has recently shown great promise in the treatment of castration-refractory prostate cancer (CRPC). Pigment Epithelium-Derived Factor (PEDF) is a natural angio-inhibitor which has been shown to be down-regulated in prostate cancer. We have previously demonstrated that the over-expression of PEDF in human CRPC PC3 cells decreased tumor growth in vivo. In the present study, we further validated PEDF anti-tumor properties in the highly metastatic CRPC LNCaP-derivative CL1 cells. We also hypothesized that PEDF could enhance the cytotoxic effects of low-dose docetaxel (Doc) and cyclophosphamide (CTX) chemotherapies in vivo. Methods: Human CRPC PC3 and CL1 cell lines were genetically modified to stably co-express the fluorescent DsRed Express protein with PEDF. Resulting cell lines were characterized in vitro for PEDF expression by Western blot and for proliferation by growth curves and clone formation in Matrigel. PEDF anti-tumor effects were assessed on established subcutaneous xenografts in mice treated with Doc (5mg/kg ip every 4 days, 1mg/kg ip daily for 10 days, 0.5mg/kg ip every other day), CTX (10-20mg/kg in the drinking water) or placebo. Survival studies were performed by injecting CL1 cells, pre-mixed with 50nM hr-PEDF or carrier control, into the left lobe of the dorsal prostate of anesthetized mice. Results: We showed that PEDF inhibits the proliferation and induces the differentiation of all CRPC cells tested in vitro. Similarly, PEDF expression decreases the development of subcutaneous PC3 and CL1 tumors in immune-compromised mice by 85% and 70%, respectively. In the survival study, we found that all control animals die within 61 days after surgery while 50% of PEDF-pretreated animals were still alive. Most importantly, we demonstrated that PEDF enhances the cytotoxic effects of low-dose chemotherapy on established tumors (best Doc dose: 1mg/kg for PC3 and 5mg/kg for CL1; best CTX dose: 10mg/kg for both PC3 and CL1). Conclusions: This data reinforces the significance of PEDF as a potential new target for the treatment of advanced prostate cancer. It also emphasizes PEDF as a promising new agent to enhance the anti-tumor efficacy of low-dose Doc and CTX chemotherapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3717. doi:1538-7445.AM2012-3717

AFM nano-mechanics and calcium dynamics of prostate cancer cells with distinct metastatic potential

BACKGROUND

Despite recent advances, it is not clear to correlate the mechanical compliances and the metastatic potential of cancer cells. In this study, we investigated combined signatures of mechanical compliances, adhesions, and calcium dynamics correlated with the metastatic potential of cancer cells.

SCOPE OF REVIEW

We used the lowly (LNCaP) and highly (CL-1, CL-2) metastatic human prostate cancer cells. The AFM-based nanomechanics was performed to determine the elastic moduli and the cell-to-substrate adhesion. The intracellular calcium dynamics was evaluated by fluorescence spectroscopy. Cell migration and the distribution of cytoskeleton were evaluated using the wounded monolayer model and immunofluorescence, respectively. The elastic moduli, the calcium dynamics, and the migratory ability are greater in CL-1 and CL-2 than LNCaP. CL-1 and CL-2 also display a significantly larger area of cell-to-substrate adhesions while the LNCaP displays a limited adhesion. These properties were slightly reduced in CL-2 compared with CL-1 cells. The enhanced elastic moduli and calcium dynamics found in CL-1 and CL-2 can be consistently explained by the intensified tensile stress generated by actin cytoskeletons anchored at more focal adhesion sites.

MAJOR CONCLUSIONS

Although the suppressed mechanical compliance of highly metastatic cells may not support the enhanced cancer metastasis, the enhanced adhesion and calcium dynamics are favorable for invasion and extra-vasation required for malignant progression.

GENERAL SIGNIFICANCE

Our results suggest that the mechanical compliance alone may fail to indicate the metastatic progression, but the combined biomechanical signatures of mechanical compliance, adhesion, and calcium dynamics can provide critical clues to determine the metastatic potential of cells.

Effect of PEDF on survival and the in vivo antitumor activities of low-dose chemotherapy in castration-refractory prostate cancer

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Background: The development of metronomic/low dose of conventional chemotherapeutic drugs have recently showed great promise in the treatment of castration-refractory prostate cancer (CPRC). Pigment Epithelium-Derived Factor (PEDF) is a natural angio-inhibitor which is down-regulated in prostate cancer. We have previously demonstrated that the over-expression of PEDF in human CRPC PC3 cells decreased tumor growth in vivo. In the present study, we further validated PEDF anti-tumor properties in the highly metastatic CRPC LNCaP-derivative CL1 cells. We also hypothesized that PEDF may enhance the cytotoxicity effects of low dose docetaxel (Doc) and cyclophosphamide (CTX) chemotherapies in vivo.

Methods: Human PC3 and CL1 cell lines were genetically modified to stably express the fluorescent DsRed Express protein with PEDF. Resulting cells were characterized in vitro for PEDF expression by western blot and, for proliferation by growth curves and clone formation in matrigel. PEDF anti-tumor effects were assessed on established s.c. xenografts in mice treated with Doc (5mg/kg ip every 4 dy, 1mg/kg ip daily for 10 days, 0.5mg/kg every other day), CTX (10-20mg/kg in the drinking water) or placebo. Survival studies were performed by injecting CL1 cells with 50nM hrPEDF or carrier control into the left lobe of the dorsal prostate of anesthetized mice.

Results: We showed that PEDF inhibits the proliferation and induces the differentiation of all CPRC cells tested in vitro. Similarly, PEDF expression decreases by 85% and 70% the development of s.c. PC3 and CL1 tumors, respectively. In the survival study, we found that all control animals die within 61 days after surgery while 50% of PEDF-pretreated animals were still alive. Most importantly, we demonstrated that PEDF enhances the cytotoxicity effects of low dose chemotherapy on established tumors (best Doc dose: 1mg/kg for PC3 and 5mg/kg for CL1; best CTX dose: 10mg/kg for PC3 and CL1).

Conclusions: These data reinforce the significance of PEDF as a potential new target for the treatment of advanced prostate cancer. It also emphasizes PEDF as a promising new agent to enhance the anti-tumor efficacy of low dose Doc and CTX chemotherapies.

Extraluminal colonic carcinoma invading into kidney: a case report and review of the literature

Renal metastasis from primary colon cancer is very rare, comprising less than 3% of secondary renal neoplasms. There are just 11 cases reported in the medical literature of colonic adenocarcinoma metastatic to the kidney. Of these cases, none occurred via direct invasion. We report a unique case of a 51-year-old female with extraluminal colonic adenocarcinoma which directly invaded into the kidney. Additionally, we investigate the causal relationship between the site of invasion and a previous stab injury by reviewing the role of the peritoneum and Gerota's fascia in preventing the spread of metastatic cancer into the perirenal space. Due to the rarity of this event, we present this case including a review of the existing literature relative to the diagnosis and treatment.

Abstract 3959: Pigment epithelium-derived factor blocks Interleukin-8 mediated proliferation in prostate cancer cells through PEDF-R/PLA2 receptor and regulation of the nuclear factor-κB and peroxisome proliferator activated receptor γ

Although extensively studied as part of the immune system, chemokines have lately been investigated as mediators of tumor development. Interleukin-8 (IL8/CXCL8) is a pro-inflammatory and pro-angiogenic transcriptional target of NF-kappaB (NFκB) and has been described as a molecular determinant of androgen independence and progression in prostate cancer (PrCa). We recently demonstrated that IL8 production is inhibited in human PrCa PC3 cells by the Pigment Epithelium Derived Factor (PEDF), a natural secreted angio-inhibitor which blocks PrCa progression. The molecular mechanisms underlying PEDF anti-tumor action are not totally clear. However, it appears that PEDF acts via several receptors with PEDF-R/PLA2 being the first high affinity receptor isolated. In the present work, we characterized the signaling pathway involved in the PEDF inhibitory effect on IL8 expression and assessed the functional effect of IL8 reduction on PrCa cells.

In order to validate IL8 repression by PEDF in PrCa cells, we treated Human androgen independent PC3 and DU145 cells with increasing doses of PEDF and quantified after 48 hours IL8 in the conditioned media. ELISA analyses showed that in both PrCa cell lines, PEDF inhibits the production of IL8. We demonstrated that IL8 down-regulation blocked PrCa cell growth in vitro as demonstrated by the use of IL8-specific neutralizing antibody. IL8 reduction was mimicked in cancer cells treated with BAY11-7082 and PDTC, two NFκB-specific inhibitors, and troglitazone, a PPARγ agonist. Accordingly, the expression and transcriptional activity of RelA/p65, the major NFκB subunit, was down-regulated in PrCa cells in response to PEDF whereas PPARγ was found up-regulated. RelA/p65 and IL8 down-regulation induced by PEDF was reversed by the GW9622 PPARγ antagonist suggesting a PPARγ-dependent pathway and locating, therefore, PPARγ upstream of NFκB. To determine if PEDF-R was involved in IL8 repression, we knocked down its expression by small interference RNA (siRNA). In these experiments, we showed that in contrast to cancer cells transfected with the non targeting control siRNA, PEDF-R siRNA transfected cells lost their ability to up-regulate PPARγ and to down-regulate RelA/p65 and IL8 in response to PEDF.

In conclusion, in this study we demonstrated that by binding to its receptor, PEDF-R, PEDF could up-regulate PPARγ, leading subsequently to suppressed NFκB-mediated transcriptional activation, reduced production of IL8 and limited proliferation of PrCa cells. These findings reinforce the strong anti-tumor potential of PEDF and suggest a new way by which PEDF curbs prostate tumor growth. These data also emphasize the fact that targeting IL8 may represent a novel therapeutic alternative for PrCa.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3959.

[Self-inflicted penile strangulation]

INTRODUCTION

Constricting devices or misappropriated means are either used to increase sexual performance or for autoerotic actions. They can lead to edema, maceration, to local infections up to Fournier gangrene or penile necrosis with or without involvement of the urethra. Injuries by these means are often challenging for the treating urologist.

CASE REPORT

A 22-year-old patient presented to the urological emergency clinic with strong penile pain and voiding difficulties. Within the scope of the clinical investigation a foreign body (frying pan handle) was found around the penis. The penis appeared to be edematous, and necrosis of the distal superficial penis segments was noted. Under local anesthesia the frying pan handle, after procurement of suitable instruments, was removed. Subsequently, a suprapubic catheter was inserted and a broad antibiotic therapy was initiated. An antiseptic local therapy completed the primary treatment. Eight weeks after the event an orthograde urethrogram was performed. The urethra appeared to behave a normal caliber without evidence for strictures or other patho-morphological changes. The final examination showed a nearly completely epithelialized glans penis, with an approximately 1-cent piece small epithelial defect.

CONCLUSIONS

Constricting devices for the penis are used to increase the sexual performance or with autoerotic intentions. Removal of the constricting devices can become impossible secondary to a hefty swelling of the penis. The treatment consists, primarily, of an immediate decompression of the strangulated penis to ensure a free blood flow and an uninhibited micturition. The removal of the various objects requires in part craft instruments. A supplementary therapy must be selected based on existing additional complications.

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

BACKGROUND

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.

MATERIALS AND METHODS

A comprehensive literature search was performed in different data bases using various key words. Relevant articles and references between 1999 and 2009 were reviewed and analyzed for data on the association between chemotherapy and initial PSA surge/flare.

RESULTS

The incidence of a PSA surge/flare-up ranges according to the reported studies between 7.6% and 13.6%. A PSA surge/flare-up was reported up to 404% from baseline PSA level followed by PSA response. The median duration of a PSA surge/flare-up is 2-3 weeks and can last up to 6-8 weeks. However, the occurrence of a PSA surge/flare-up did not impact outcome and survival negatively compared to patients with an immediate PSA response.

CONCLUSIONS

A considerable portion of CRPC patients experience an initial PSA surge/flare-up under systemic chemotherapy. The definitions used for PSA surge/flare-up differ slightly in the literature. This issue needs to be solved since it might impact defining treatment response. As a PSA surge/flare-up did not impact outcome and survival negatively, chemotherapy should be continued according to the literature addressing specifically the phenomenon of a PSA surge/flare-up for a minimum of 8 weeks or 3 rounds of a 3-weekly cycle chemotherapy regimen before further decisions are made about efficacy. However, Scher et al. recommended a 12-week period drug exposure based on their results on PSA progression-free survival and overall survival. This dilemma needs to be addressed in further data analysis in order to establish a general rule regarding when to stop chemotherapy. Physicians should be aware of this effect to avoid inadequate early discontinuation of chemotherapy. The underlying mechanisms of a PSA surge/flare-up are still elusive and need further clarification.

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

Background

The 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.

Results

Markedly 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.

Conclusion

These 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.

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.

Deleted in cancer 1: Search for a function in prostate cancer

e16095

Background: Deleted In Cancer 1 (DICE1/INTS6) gene was recently identified to colocalize with the microsatellite marker D13S284 in 13q14.3, a region frequently affected by allelic deletion in many solid tumors including prostate cancer (PrCa). DICE1 missense mutations have been previously detected in PrCa cell line LNCap, and reduced DICE1 expression appears to be associated with CpG promoter hypermethylation in PrCa cells. DICE1 is a highly conserved nuclear protein suggesting its involvement in DNA repair, transcription, or RNA splicing. In mouse, the DICE1 homologue interferes with the response to insulin-like growth factor 1 and suppresses anchorage-independent growth of transformed mouse cells. The totality of these results suggests that DICE1 is a tumor suppressor gene and insist on the need to better characterize DICE1 function in PrCa. Methods: Expression of DICE1 was evaluated by Northern Blot in PrCa cell lines LNCap, DU145, PC3, PC3ml and CPTX1532 and compared to expression level in normal prostate cell line NPTX1532. DICE1 growth inhibitory effects were analyzed by colony formation assay on PC3 and DU145 cells transfected with DICE1 expression plasmid or control vector. Apoptosis was assessed by visualization of genomic DNA fragmentation on agarose gel. PCR arrays (SABiosciences) were used to identify specific signaling pathways modulated in response to DICE1 expression. Results: Markedly decreased DICE1 mRNA levels were detected in PrCa cell lines LNCap, DU145, PC3 and PC3ml as well as CPTX1532 as compared to NPTX1532, a cell line derived from normal prostate tissue. Ectopic expression of DICE1 cDNA in DU145 and PC3 cells substantially suppressed their ability to form colonies in vitro. This growth inhibition was not due to immediate induction of apoptosis suggesting growth suppression by other pathways. Expression profiling identified multiple pathways, such as Wnt, Hedgehog, PI-3 Kinase, NFκB and Insulin pathways, regulated in response to ectopic DICE1 expression. Furthermore, various transcription factors including Fos, Jun, CEBPA and PPAR-γ were up-regulated in response to DICE1. Conclusions: These results clearly illustrate the growth inhibitory ability of DICE1 in PrCa. Expression profiling links DICE1 function to growth factor signaling and cell-cell communication.

No significant financial relationships to disclose.

Pigment epithelium-derived factor and interleukin-6 control prostate neuroendocrine differentiation via feed-forward mechanism

PURPOSE

PEDF (pigment epithelium-derived factor) promotes the differentiation and survival of neuronal cells, and expands the adult neuronal stem cell niche. In the prostate PEDF is suppressed by androgen with unclear physiological consequences. We report that PEDF induced the neuroendocrine differentiation of prostate cancer cells, which was accompanied by neurite outgrowth and chromogranin A expression.

MATERIALS AND METHODS

We performed neuroendocrine differentiation assay, Western blot analysis, immunostaining and reverse transcriptase-polymerase chain reaction in the human prostate cancer cell lines LNCaP, PC-3 and DU145, and the prostate epithelial strain RWPE-1 (ATCC).

RESULTS

Ectopic and endogenous PEDF caused neuroendocrine differentiation of prostate cancer cells, as manifested by neurite-like outgrowths and chromogranin A expression. The transdifferentiated cells expressed axonal and dendritic markers, as ascertained by immunoblotting for specific markers. Neuroendocrine cells formed multiple synaptophysin positive protrusions resembling dendritic spines and vesicles containing serotonin, pointing to possible synapse formation. The known transdifferentiating agent interleukin-6 induced PEDF secretion. Moreover, PEDF neutralizing antibodies abolished the transdifferentiation of interleukin-6 treated cells, suggesting an autocrine loop. Neurogenic events were independent of cyclic adenosine monophosphate. Instead, PEDF activated in this order RhoA, nuclear factor kappaB and Stat3. Inhibitors of the Rho, nuclear factor kappaB and STAT pathways abolished differentiation and synapse formation. Additionally, nuclear factor kappaB activation caused interleukin-6 expression.

CONCLUSIONS

We discovered that nuclear factor kappaB controls the formation of neuronal communications in the prostate due to PEDF. We defined a feed-forward loop, in which nuclear factor kappaB induction elicits Stat3 activation and pro-differentiating interleukin-6 expression causes the further expansion of neuroendocrine communications. Our findings point to the role of nuclear factor kappaB and PEDF in coordinated prostate development.

Androgen receptor targets NFkappaB 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 NFkappaB, 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 NFkappaB suppression, since it was restricted to the cells lacking nuclear (active) NFkappaB. Thus we for the first time identified combined decrease of NFkappaB 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. (c) 2007 Wiley-Liss, Inc.

Evaluation of peri-operative peripheral and renal venous levels of pro- and anti-angiogenic factors and their relevance in patients with renal cell carcinoma

OBJECTIVE

To evaluate peri-operative peripheral and renal venous plasma levels of vascular endothelial growth factor (VEGF), platelet-derived growth factor type BB (PDGF-BB), transforming growth factor (TGF)-beta1, endostatin, and thrombospondin-1 (TSP-1) in relation to pathological variables and prognosis, as pro- and anti-angiogenic factors are important for tumour growth and treatment of patients with renal cell carcinoma (RCC).

PATIENTS AND METHODS

The study included 74 consecutive patients with sporadic RCC who had tumour nephrectomy. Peripheral venous blood was drawn 1 day before, immediately and 1, 3 and 5 days after surgery. Renal venous blood was collected in a subgroup of 33 patients during surgery. The variables were analysed using quantitative enzyme-linked immunoassay kits, and associated with pathological variables and disease-specific survival.

RESULTS

Soon after surgery, peripheral venous VEGF, PDGF-BB and TGF-beta1 levels were decreased, whereas endostatin levels were significantly increased. Renal venous VEGF, PDGF-BB and TGF-beta1 levels were higher than in the general venous blood pool. Renal venous VEGF levels were correlated with tumour diameter and associated with grade and vascular invasion. After a mean follow-up of 30 months, higher peripheral preoperative, early peripheral postoperative and renal venous VEGF levels were associated with a poorer prognosis. However, in a multivariate analysis only Tumour-Node-Metastasis stage and Eastern Cooperative Oncology Group performance status were independent prognosticators of disease-specific survival.

CONCLUSIONS

Circulating pro- and anti-angiogenic factors change early after nephrectomy. VEGF, PDGF-BB and TGF-beta1 are higher in the renal vein than in the general venous blood pool. Higher renal venous and peripheral levels of VEGF might be associated with a poorer prognosis.

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

OBJECTIVES

The 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.

METHODS

We 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.

RESULTS

The 74 patients were stratified into four groups: response, partial response, flare-up-initial PSA elevation, and progression. Median survival in the flare-up group (n=8) was 20 months and did not differ from the response group (p=0.564). The flare-up group showed a maximum PSA elevation from baseline between 3.4 and 28.3% (between three and six weeks) followed by PSA decline >or=50% from the baseline level in seven of the eight patients. The androgen receptor mutations AR(877) and AR(715) 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 AR(WT), respectively.

CONCLUSIONS

A considerable portion of HRPC patients experience an initial PSA flare-up under systemic chemotherapy. In this study, occurrence of flare-up phenomenon did not impact survival. Chemotherapy should be continued a minimum of six weeks 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.

Clinical outcome of patients (pts) with taxane-resistant (TR) hormone-refractory prostate cancer (HRPC) treated with second-line cyclophosphamide (CP) -based metronomic chemotherapy

15647

Background: For pts with TR HRPC no standard chemotherapeutic treatment exist. In this study we evaluate the efficacy of CP-based metronomic chemotherapy in this pt population. Methods: Pts with metastatic HRPC with disease progression under docetaxel-based chemotherapy were eligible. The primary endpoint was PSA response. Secondary endpoints were time to progression (TTP), survival and toxicity. Low dose CP (50 mg/d) and dexamethasone (1 mg/d) were administered orally in a metronomic manner. Treatment was continued until disease progression. Results: Between February 2005 and May 2006 17 pts were enrolled in this study. The median follow-up was 12 weeks (range: 4–60). Median Age was 68 years (range: 42–85). Median PSA at study entry was 134 ng/ml (range: 46.0–6554). 9 pts had a PSA response (medium 44.4%), 4 pts = 50% and 5 pts < 50%. 8 pts had a PSA progression. The medium time to maximal response was 12 weeks (range: 4–36). TTP/survival for pts with PSA response and PSA progression was 24/60 weeks and 4/4 weeks, respectively. 3 pts of the progression group showed a decrease in PSA doubling time. 5 pts reported a decrease in bone pain after 4 weeks treatment. No grade 3 and 4 toxicities were noted. Conclusions: In this study, low-dose metronomic administered CP demonstrated efficacy as second line treatment in pts with TR HRPC. The treatment was well tolerated and almost without toxicity. The mechanism of action of low dose CP involves inhibition of tumor angiogenesis secondary to inhibition of dividing endothelial cells in tumor associated blood vessels. Dexamethasone may also have antiangiogenic properties by inhibiting the production of vascular endothelial growth factor. Further investigation regarding an antiangiogenic treatment strategy for HRPC are therefore of great interest.

No significant financial relationships to disclose.

Deleted In Cancer 1 (DICE1): Search for a function in prostate carcinoma (PCa)

15634

Background: Recently, DICE1 gene (MIM 604331 ) was identified to colocalize with the microsatellite marker D13S284 in 13q14.3, a region frequently affected by allelic deletion in PCa. We previously showed that DICE1 mRNA expression is down-regulated in PCa cell lines compared to normal prostate tissue, due to DICE1 promoter hypermethylation; suggesting that DICE1 is a tumor suppressor gene. Methods: Human PCa cell lines PC3 and DU145 were lipo-transfected with mammalian expression plasmids encoding for the full length DICE1 gene or for its N- (APAI construct) and C-terminal (DEAD construct) fragments. The constructs expression was determined by semi-quantitative PCR and quantified by Real-time PCR. Clonogenic formation and apoptotic assays were performed. Results: The PCR analysis showed that the expression of DICE1, APAI and DEAD domains in transfected PC3 and DU145 cell lines was increased 30.6, 75.2 and 27.9 fold in PC3 cells and 4.3, 5 and 2.5 fold in DU145 cells, respectively, compared to non-transfected cells. The function analysis showed that the ectopic expression of DICE1 suppressed clonogenic growth of PC3 and DU145 cell lines. Surprisingly, we showed that like DICE1, DEAD and APAI inhibit the PC3 and DU145 clonogenic growth suggesting that both regions are involved in prostate tumor growth inhibition. The apoptosis assay could not show any DNA fragmentation activity for DICE1. Conclusions: We demonstrated that DICE1 is a tumor suppressor in PCa. DICE1 mRNA expression is down-regulated in PCa cell lines compared to normal prostate tissue and its ectopic expression in PCa cell lines inhibits their capacity to form clonogenic colonies in vitro. The functional analysis could not reveal any role of DICE1 in PCa apoptosis, suggesting that other molecular mechanisms are involved.

No significant financial relationships to disclose.

A randomized study of docetaxel and dexamethasone with low- or high-dose estramustine for patients with advanced hormone-refractory prostate cancer

OBJECTIVE

To test the combination of docetaxel with two different doses of estramustine in patients with hormone-refractory prostate cancer (HRPC), to improve response rates and to lower side-effects, as docetaxel-based chemotherapy is an increasing option for men with advanced HRPC, and alone or combined with estramustine, docetaxel improves median survival.

PATIENTS AND METHODS

In all, 72 patients with metastatic HRPC were randomly assigned to receive docetaxel (70 mg/m(2) intravenously, on day 2 every 21 days) and estramustine (3 x 280 mg/day oral starting 1 day before docetaxel, for 5 consecutive days) for arm A, or estramustine (3 x 140 mg/day oral starting 1 day before docetaxel, for 3 consecutive days) for arm B. Premedication with oral dexamethasone at a total daily dose of 16 mg, in divided doses twice a day was administered in arm A on day 1-5 and in arm B on day 1-3. Initially, six cycles were administered. Chemotherapy was restarted after a significant increase in prostate-specific antigen (PSA) level. Patients were monitored for any measurable PSA response and toxicity.

RESULTS

Between the arms there was no statistically significant difference in time to progression and overall survival. However, treatment B had less treatment-related toxicity than A. Independent prognostic variables were baseline factors like PSA level, haemoglobin level, Eastern Cooperative Oncology Group performance status, and bone pain at presentation.

CONCLUSIONS

In this randomized phase II study the combination of docetaxel and estramustine had substantial activity in HRPC, with a significant incidence of severe toxicity, both haematological and not. Nevertheless, treatment-related toxicity was predictable and manageable. There was no better effect with a higher dose of estramustine with docetaxel than for a lower dose. There was a slight tendency to higher toxicity for high-dose estramustine but this was not statistically significant. The present results support the assertion that estramustine is not necessary in docetaxel-based treatment regimens.

[Idiopathic retroperitoneal fibrosis (Ormond's disease)]

INTRODUCTION

Idiopathic retroperitoneal fibrosis (RPF) represents a rare inflammatory disease, which leads to extensive fibrosis of the retroperitoneal space. In the course of the progressive fibrosis, fibrous tissue compresses the retroperitoneal structures with the development of consecutive ureteral obstruction. Because of the unknown aetiology, no consensus between conservative and surgical treatment exists.

CASE REPORT

A 60-year-old patient was admitted to hospital with left-sided flank pain, hydronephrosis, and retroperitoneal tumour. A CT scan-guided biopsy revealed RPF. The hydronephrosis was treated by endoluminal urinary diversion. Under simultaneous administration of steroids, an almost complete regression of the RPF was noted.

CONCLUSIONS

First goal in the treatment of RPF is urinary diversion to protect the renal function. A simultaneous therapy with steroids can cause a complete regression of the RPF. Surgical intervention is only recommended in refractory cases.

Randomized study of docetaxel (D) and dexamethasone (DX) with low or high dose estramustine (E) for patients with advanced hormone-refractory prostate cancer (HRPC)

4653

Background: D-based chemotherapy is a burgeoning option for men with advanced HRPC. Alone or in combination with E, D has been shown to improve median survival. In this study we tested the combination of D with two different doses of E in patients (pts) with HRPC to improve response rates and to lower side effects. Methods: 72 metastatic HRPC pts were randomly assigned to receive D (70 mg/m2 IV, d2, q3w) and E (3 × 280 mg/d PO starting 1 day prior to D, for 5 consecutive days) for arm A or E (3 x 140 mg/d PO starting 1 day prior to D, for 3 consecutive days) for arm B. Premedication with oral DX at a total daily dose of 16 mg, in divided doses two times a day was administered in arm A on day 1 to 5 and in arm B on day 1 to 3. Initially, 6 cycles were administered and repeated after significant PSA rise. Pts were monitored for PSA response, time to progression (TTP), survival and toxicity. Results: PSA declines of ≥75%, ≥50% and ≤50% were 36.8%, 55.3% and 44.7% in arm A and 38.2%, 67.6% and 32.4% in arm B, respectively (P = .442). TTP in Arm A and Arm B were 11 months (95% CI, 7–14) versus 14 months (95% CI, 8–19), P = .6911) and overall survival 21 months (95% CI, 6–35) versus 22 months (95% CI, 18–27), respectively, (P = .4149). The primary treatment-related side effects observed in arm A and arm B were granulocytopenia (34% and 29%, P = .663) and thrombotic complications caused by E (four pts (11%) and one pt (3%), respectively, P = .206). Associated baseline factors with overall survival in univariate analysis were ECOG performance status (P < .001), hemoglobin level (P < .001), bone pain (P < .001), and PSA (P < .097) and in multivariate analysis ECOG performance status (95% CI, 2.9–13.9) and bone pain (95% CI, 3.2–20.1), (P < .001). Conclusions: In this randomized phase II study the combination of D and E had substantial activity in HRPC. We did not find a statistically significant difference of higher dose of E in combination with D compared to a lower dose of E and D regarding PSA response, TTP and survival. However, there was a tendency of higher toxicity in the high dose E group. These treatment-related toxicities were mainly hematologic and manageable. The results of this study support the assertion that estramustine is not necessary in docetaxel-based treatment regimens.

No significant financial relationships to disclose.

Characterization of prognostic factors and efficacy in a phase-II study with docetaxel and estramustine for advanced hormone refractory prostate cancer

BACKGROUND

Docetaxel based chemotherapy not only reduces pain and improves quality of life in advanced hormone refractory prostate cancer (HRPC), but it also improves survival. We investigated the combination of docetaxel and estramustine in patients with HRPC regarding efficacy and prognostic parameters.

PATIENTS AND METHODS

We conducted a phase-II trial, administering docetaxel (70 mg/m(2) i.v., day 2, every 3 weeks) and estramustine (280 mg 3 times daily p.o., 1 day prior to docetaxel, on 5 consecutive days) to patients with HRPC. Patients were monitored for PSA (prostate-specific antigen) response and toxicity.

RESULTS

62 patients were treated. The median age was 67.5 years, the median PSA was 177.9 ng/ml. The median number of cycles was 6. The median time to progression (TTP) and median survival time were 14 (+/-2) and 24 (+/-5) months, respectively. A = 50% decrease in PSA levels from baseline occurred in 38 (61.3%) patients of whom 25 (40.3%) had a = 75% PSA decrease. The main grade 3-4 hematologic toxicities were neutropenia 34% and anemia 18%.

CONCLUSIONS

The combination of docetaxel and estramustine exerts substantial activity in HRPC suggesting an overall survival benefit with manageable toxicity. This trial also demonstrated a survival advantage for patients with early chemotherapeutic intervention. We identified PSA relapse, baseline PSA and hemoglobin as valuable prognostic factors in this setting.

In vivo upregulation of CD95 and CD95L causes synergistic inhibition of angiogenesis by TSP1 peptide and metronomic doxorubicin treatment

Antiangiogenic thrombospondin-1 (TSP1) induces endothelial cell death via a CD95-mediated cascade. We used this signaling pathway, where CD95/Fas is a rate-limiting intermediate, as a target to optimize the efficacy of TSP1 active peptide, DI-TSP. Like TSP1, DI-TSP upregulated endothelial CD95L in vivo. To modulate CD95 levels, we chose chemotherapy agent doxorubicin (DXR). DXR caused sustained upregulation of CD95 in the activated endothelium at 1/100 of the maximal tolerated dose. DI-TSP and DXR synergistically induced endothelial apoptosis in vitro, and in vivo, in developing murine vessels. Fas decoy, TSP1 receptor antibody and Pifithrin, a p53 inhibitor, severely decreased apoptosis and restored angiogenesis by DXR-DI-TSP combination, evidencing critical roles of CD95 and TSP1. Combined therapy synergistically blocked neovascularization and progression of the bladder and prostate carcinoma. Such informed design of a complex antiangiogenic therapy based on the rate-limiting molecular targets is a novel concept, which may yield new approaches to cancer treatment.

Two Functional Epitopes of Pigment Epithelial–Derived Factor Block Angiogenesis and Induce Differentiation in Prostate Cancer

Pigment epithelial-derived factor (PEDF), an angiogenesis inhibitor with neurotrophic properties, balances angiogenesis in the eye and blocks tumor progression. Its neurotrophic function and the ability to block vascular leakage is replicated by the PEDF 44-mer peptide (residues 58-101). We analyzed PEDFs' three-dimensional structure and identified a potential receptor-binding surface. Seeking PEDF-based antiangiogenic agents we generated and tested peptides representing the middle and lower regions of this surface. We identified previously unknown antiangiogenic epitopes consisting of the 34-mer (residues 24-57) and a shorter proximal peptide (TGA, residues 16-26) with the critical stretch L19VEEED24 and a fragment within the 44-mer (ERT, residues 78-94), which retained neurotrophic activity. The 34-mer and TGA, but not the 44-mer reproduced PEDF angioinhibitory signals hinged on c-jun-NH2-kinase-dependent nuclear factor of activated T cell deactivation and caused apoptosis. Conversely, the ERT, but not the 34-mer/TGA induced neuronal differentiation. For the 44-mer/ERT, we showed a novel ability to cause neuroendocrine differentiation in prostate cancer cells. PEDF and the peptides bound endothelial and PC-3 prostate cancer cells. Bound peptides were displaced by PEDF, but not by each other, suggesting multiple receptors. PEDF and its active fragments blocked tumor formation when conditionally expressed by PC-3 cells. The 34- and 44-mer used distinct mechanisms: the 34-mer acted on endothelial cells, blocked angiogenesis, and induced apoptosis whereas 44-mer prompted neuroendocrine differentiation in cancer cells. Our results map active regions for the two PEDF functions, signaling via distinct receptors, identify candidate peptides, and provide their mechanism of action for future development of PEDF-based tumor therapies.