Ahmed El-Zawahry

Lysosomotropic acid ceramidase inhibitor induces apoptosis in prostate cancer cells

PurposeAlterations in ceramide metabolism have been reported in prostate cancer (PCa), resulting in escape of cancer cells from ceramide-induced apoptosis. Specifically, increased expression of lysosomal acid ceramidase (AC) has been shown in some primary PCa tissues and in several PCa cell lines. To determine if this represents a novel therapeutic target, we designed and synthesized LCL204, a lysosomotropic analog of B13, a previously reported inhibitor of ACMethodsProstate cancer cell lines were treated with LCL204 for varying times and concentrations. Effects of treatment on cytotoxicity, sphingolipid content, and apoptotic markers were assessed.ResultsTreatment of DU145 PCa cells resulted in increased ceramide and decreased sphingosine levels. Interestingly, LCL204 caused degradation of AC in a cathepsin-dependent manner. We also observed rapid destabilization of lysosomes and the release of lysosomal proteases into the cytosol following treatment with LCL204. Combined, these events resulted in mitochondria depolarization and executioner caspase activation, ultimately ending in apoptosisConclusionsThese results provide evidence that treatment with molecules such as LCL204, which restore ceramide levels in PCa cells may serve as a new viable treatment option for PCa.

New insights on the use of desipramine as an inhibitor for acid ceramidase

Treatment of different cancer cell lines with desipramine induced a time‐ and dose‐dependent downregulation of acid ceramidase. Desipramines effect on acid ceramidase appeared specific for amphiphilic agents (desipramine, chlorpromazine, and chloroquine) but not other lysomotropic agents such as ammonium chloride and bafilomycin A1, and was not transcriptionally regulated. The cathepsin B/L inhibitor, CA074ME, but not the cathepsin D inhibitor, pepstatin A, blocked desipramines effect on acid ceramidase. Desipramine led to a more pronounced downregulation of sphingosine compared to ceramide suggesting acid ceramidase inhibition is important to desipramines mechanism of action. This study reveals a new mechanism of action for desipramine.

Doxorubicin increases the effectiveness of Apo2L/TRAIL for tumor growth inhibition of prostate cancer xenografts

BackgroundProstate cancer is a significant health problem among American men. Treatment strategies for androgen-independent cancer are currently not available. Tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) is a death receptor ligand that can induce apoptosis in a variety of cancer cell lines, including androgen-independent PC3 prostate carcinoma cells. In vitro, TRAIL-mediated apoptosis of prostate cancer cell lines can be enhanced by doxorubicin and correlates with the downregulation of the anti-apoptotic protein c-FLIP. This study evaluated the effects of doxorubicin on c-FLIP expression and tumor growth in combination with Apo2L/TRAIL in a xenograft model.MethodsIn vitro cytotoxic effects of TRAIL were measured using a MTS-based viability assay. For in vivo studies, PC3 prostate carcinoma cells were grown subcutaneously in athymic nude mice and tumor growth was measured following treatment with doxorubicin and/or Apo2L/TRAIL. c-FLIP expression was determined by western blot analysis. Apoptosis in xenografts was detected using TUNEL. Statistical analysis was performed using the student t-test.ResultsIn vitro experiments show that PC3 cells are partially susceptible to Apo2L/TRAIL and that susceptibility is enhanced by doxorubicin. In mice, doxorubicin did not significantly affect the growth of PC3 xenografts but reduced c-FLIP expression in tumors. Expression of c-FLIP in mouse heart was decreased only at the high doxorubicin concentration (8 mg/kg). Combination of doxorubicin with Apo2L/TRAIL resulted in more apoptotic cell death and tumor growth inhibition than Apo2L/TRAIL alone.ConclusionsCombination of doxorubicin and Apo2L/TRAIL is more effective in growth inhibition of PC3 xenografts in vivo than either agent alone and could present a novel treatment strategy against hormone-refractory prostate cancer. The intracellular mechanism by which doxorubicin enhances the effect of Apo2L/TRAIL on PC3 xenografts may be by reducing expression of c-FLIP.

Acid ceramidase inhibition: a novel target for cancer therapy

During the last decade, sphingolipid deregulation, namely the balance between the pro-apoptotic molecule ceramide and the anti-apoptotic sphingolipid sphingosine-1-phosphate, has emerged as an important factor in cancer pathology and resistance to therapy. Thus, our research has been focused on developing drugs that are able to restore normal sphingolipid balance, precisely through increasing the levels of ceramide and decreasing sphingosine-1-phosphate. Particularly, inhibition of the ceramide metabolizing enzyme acid ceramidase, whose over-expression in cancer cells has been implicated in resistance to treatment, is proving to be an efficient and promising strategy. In this review, we consider our recent work with acid ceramidase inhibitors, in combination with radiation or gene therapy as a sensitizer that enhance cancer therapy.

Resistance to TRAIL is associated with defects in ceramide signaling that can be overcome by exogenous C6-ceramide without requiring down-regulation of cellular FLICE inhibitory protein

Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor superfamily that selectively induces apoptosis in malignant cells. However, not all cancer cells are susceptible to TRAIL and mechanisms of resistance and new strategies to enhance sensitivity are an area of intense investigation. Glucose withdrawal or paclitaxel increase intracellular ceramide, down-regulate cellular FLICE inhibitory protein (cFLIP), and sensitize cells to TRAIL. Therefore, we investigated whether TRAIL resistance is due to ceramide levels and/or defects in ceramide generation following ligand binding. Colon cancer cells isolated from the primary tumor (SW480) and a subsequent metastasis (SW620) of the same patient have different sensitivities to TRAIL. Mass spectrometry was used to compare ceramide content in untreated and TRAIL-treated cells. Overall levels of ceramide were comparable in the cell lines but TRAIL-sensitive SW480 cells contained a higher percentage of C16-, and C18-ceramide and lower C24-ceramides than TRAIL-resistant SW620 cells. Upon TRAIL treatment, ceramide (primarily C16-ceramide) increased in SW480 but not SW620 cells. The increase in ceramide occurred with slow kinetics, paralleling caspase-3/7 activation. Combination of C6-ceramide with TRAIL resulted in apoptosis of SW620 cells. However, exogenous C6-ceramide did not affect levels of cFLIP nor did pretreatment sensitize cells to TRAIL. Exposure to TRAIL prior to ceramide was required to induce apoptosis, suggesting that ceramide plays a role in enhancing or amplifying TRAIL-mediated signaling. Our results suggest that ceramide plays a role in promoting TRAIL-mediated apoptosis and that TRAIL-resistant cancers may benefit from combination therapy with ceramide or agents that enhance ceramide accumulation.

The present and future for gene and viral therapy of directly accessible prostate and squamous cell cancers of the head and neck

Gene therapy has been in a continuous evolutionary process since the first approved trial occurred in 1990 at the National Institute of Health. In the USA, as of March 2004, there were 619 approved gene therapy/transfer protocols and 405 of these were for cancer treatment. Another 294 trials are in progress worldwide, with most concentrated in Europe. However, cancer gene therapy is in its relative infancy when compared with the well-established use of chemo-radiotherapy for treating cancer. As the field develops it is becoming clear that using gene therapy in conjunction with established chemo-radiotherapy approaches is yielding the best results. This concept shall be reviewed in the context of the status of the field, and a future direction based on a combination of gene therapy with small molecule modification of sphingolipid metabolism shall be discussed.

Ceramide, Ceramidase, and FasL Gene Therapy in Prostate Cancer

Glycerolipid-derived second messengers such as diacylglycerol, phosphatidylinositides, and eicosanoids are now well-established mediators of signal transduction. Sphingolipids, which are even more structurally complex than glycerophospholipids, are also appreciated to serve as potential reservoirs for bioactive lipids (1, 2, 3, 4, 5, 6, 7, 8, 9). Thus, regulation of sphingolipid metabolism appears involved in regulation of cell growth, differentiation, senescence, and programmed cell death, and possibly, as proposed herein, favoring growth of a subset of prostate cancers.

Capromab Pendetide Scanning Has a Potential Role in Optimizing Patient Selection for Salvage Cryosurgical Ablation of the Prostate

OBJECTIVES To evaluate an algorithm using Capromab pendetide scanning (CPS) and prostate biopsy to select appropriate patients with biochemical recurrence (BCR) after radiation therapy (RT) for salvage cryosurgical ablation of the prostate (CSAP) and to avoid premature androgen deprivation therapy (ADT); and to estimate the local salvage success rate for patients with high-risk clinical features. METHODS Sixty-nine patients underwent a history, physical, CPS, and prostate biopsy. Patients with a negative or prostate-only positive signal and a positive biopsy were offered CSAP. Success was defined as a postsalvage nadir PSA of ≤ 0.4 ng/mL. Patients who failed were followed to establish when they required ADT. The results were compared with the putative results of applying clinical parameters alone. Patients were considered high-risk if they had any of the following characteristics: stage T3B-T4, Gleason ≥ 4 + 3, PSADT ≤ 10 months or presalvage PSA > 10 ng/mL. RESULTS Twelve patients (6 with metastatic signal and 6 with negative biopsy) were excluded. Fifty-seven patients underwent CSAP. Overall 67% were successfully treated. Pre-salvage PSA was significantly associated with success (P = .013). Using clinical risk alone, only 14 patients achieved success compared with 38 using our algorithm. Most of the patients (75%) avoided ADT over a period of 21 months. CONCLUSIONS Using our algorithm with CPS and prostate biopsy enabled us to spare some low-risk patients the undue morbidity of local salvage procedures that are likely to fail, while offering selected high-risk patients the opportunity for cure, avoiding premature ADT. Low presalvage PSA seems to be correlated with successful outcomes.

Mesh for Anterior Pelvic Organ Prolapse: Where Do We Go Now?

Pelvic organ prolapse (POP) repair using native tissue has a significant risk of failure, especially for anterior compartment repair. Surgical techniques using a variety of mesh grafts and approaches have been developed to decrease the risk of recurrence and improve overall outcomes. Some, but not all, studies have demonstrated that synthetic mesh grafts and mesh kits improve objective outcomes. However, reports of complications with the use of synthetic mesh grafts and mesh kits have been emerging. Such reports have stirred the interests of physicians, medical societies, the media, and regulatory agencies such as the US Food and Drug Administration (FDA), which in July 2011 issued a Safety Communication updating a 2008 statement warning about synthetic mesh and mesh kit complications associated with POP repair. This article discusses current and future directions using synthetic mesh for anterior compartment POP repair in the context of the recent FDA communication.

MP27-20 CONVECTIVE RADIOFREQUENCY WATER VAPOR ENERGY PROSTATE ABLATION (REZUM®) EFFECTIVELY TREATS URINARY RETENTION

INTRODUCTION AND OBJECTIVES: New minimally invasive surgical therapies (MIST) for lower urinary tract symptoms due to benign prostatic hyperplasia (LUTS/BPH) such as prostatic urethral lift and convective radiofrequency water vapor energy prostate ablation (WaVE) have shown promising intermediate-term results in improving voiding symptoms. However, the initial trials excluded men in urinary retention; thus the ability of these new technologies to achieve catheter independence has not been evaluated. This study investigated outcomes of patients with urinary retention at baseline treated with WaVE. METHODS: Patients in urinary retention who underwent WaVE were retrospectively identified. Urinary retention was defined as dependence on an indwelling catheter or performance of clean intermittent catheterization (CIC) for bladder emptying. Age, duration of catheter dependence, prostate size, baseline IPSS and PVR, and number of treatments per procedure were recorded. For subjects with successful trials without catheter (TWOC), time to catheter independence and post-procedure PVR and IPSS were recorded. Baseline characteristics between subjects with successful TWOC and unsuccessful TWOC were compared using Mann Whitney U test and T-test for continuous variables and Chi-square test and Fisher0s exact test for non-continuous variables. RESULTS: 30 patients were identified with urinary retention who underwent WaVE. 22 subjects had an indwelling catheter, 8 subjects performed clean intermittent catheterization (CIC). Mean age was 76 years. Relevant baseline measures included (mean): duration of catheter dependence (6.9mo), prostate size (64.3 ml), PVR (538 mL), and number of treatments per procedure (6.4). 28/30 subjects had middle lobe treatment (1 treatment per procedure). 23 of 30 subjects (77%) achieved successful TWOC post-procedure. Mean time to catheter independence was 29 days post-procedure with mean post-procedure PVR 84 mL and post-procedure IPSS 9. There were no differences between subjects with or without successful TWOC in age, duration of catheter dependence, prostate size, baseline PVR, baseline IPSS, number of treatments per procedure, or treatment of median lobe. CONCLUSIONS: WaVE can effectively treat patients with urinary retention and successfully render patients catheter independent, including patients with a median lobe. Longer-term follow up is necessary to evaluate the durability of this technology.