Ronan Coffey

Regulation of Fas antibody induced neutrophil apoptosis is both caspase and mitochondrial dependent

Resolution of neutrophil mediated inflammation is achieved, in part, through induction of neutrophil apoptosis. This constitutively expressed programme can be delayed by inflammatory mediators and induced by ligation of the Fas receptor. However, functional activation of the neutrophil results in resistance to Fas signalled death. We evaluated the effects of Fas antibody engagement on caspase activation and mitochondrial permeability, and the impact of co‐stimulation by lipopolysaccharide (LPS) or granulocyte macrophage‐colony stimulating factor (GM‐CSF) on these events. Fas engagement by an agonistic anti‐Fas antibody resulted in enhanced caspase 3 and 8 activity and increased mitochondrial permeability. Studies with pharmacological inhibitors of caspase activity showed that activation of caspase 8 occurred before, and activation of caspase 3 occurred after mitochondrial disruption. The mitochondrial stabilising agent bongkrekic acid also inhibited caspase activation and apoptosis. LPS, GM‐CSF and increased glutathione stabilised the mitochondria and inhibited caspase 3. Caspase 8 activity was also inhibited by co‐stimulation through a mechanism independent of mitochondrial stabilisation. Glutathione directly inhibited caspase 3 and 8 activity. We conclude inhibition of Fas antibody induced apoptosis by inflammatory proteins is associated with augmented mitochondrial stability and reduced caspase 3 activity that may be glutathione mediated.

Caffeic acid phenethyl ester-induced PC-3 cell apoptosis is caspase-dependent and mediated through the loss of inhibitors of apoptosis proteins

To investigate the effects of a novel agent, caffeic acid phethyl ester (CAPE) on nuclear factor (NF)‐κB activation and apoptosis in the androgen‐independent PC3 prostate cancer cell line.

SIGNALING FOR THE CASPASES: THEIR ROLE IN PROSTATE CELL APOPTOSIS

PURPOSE The caspases are an evolutionary conserved family of cell death proteases. Their activation during apoptosis is an important underlying theme in prostate cancer therapy. We summarize the signaling pathways leading to the recruitment of the caspases and address the importance of recent therapeutic strategies aimed at specifically targeting these proteases in relation to prostate cancer. MATERIALS AND METHODS We present a background introduction into the role of the caspases in apoptosis and how failure to signal effectively their activation may contribute to prostate cancer progression. Key studies aimed at specifically targeting the caspases as cancer therapy are discussed. RESULTS Prostate carcinogenesis and apoptosis are related. The deregulation of apoptosis contributes to tumor initiation, metastasis and progression to the androgen insensitive state. Conversely the effectiveness of therapy often depends on its ability to induce apoptosis in prostate cancer cells. Identifying abnormalities in the apoptotic signaling pathway has greatly contributed to understanding the biology of prostate cancer. Elucidating caspase regulation has contributed to the design of novel therapies for prostate cancer. CONCLUSIONS We summarize the physiological and pathological pathways leading to caspase activation in the prostate and describe novel approaches that target these proteases.

Priming prostate carcinoma cells for increased apoptosis is associated with up-regulation of the caspases.

The potential to prime prostatic carcinoma cell lines for apoptosis represents an exciting strategy for the treatment of patients with this disease. The ability and the underlying molecular mechanisms involved in sensitizing both androgen‐sensitive and androgen‐insensitive cell types to a range of apoptotic‐inducing agents are investigated by the authors.

Resistance to caspase-dependent, hypoxia-induced apoptosis is not hypoxia-inducible factor-1 alpha mediated in prostate carcinoma cells

Hypoxia occurs in association with cancer development, the result being a more aggressive and metastatic cancer phenotype. Hypoxia, which activates hypoxia‐inducible factor‐1 alpha (HIF‐1α), is associated with a number of cellular changes including increased apoptotic resistance. The authors hypothesized that HIF‐1α is central to the cells ability to resist apoptosis induced during the hypoxia selection process.

Effects of Cyclic Stretch On Prostatic Cells in Culture

PURPOSE The fundamental process in the development of benign prostatic hyperplasia (BPH) is a loss of homeostasis between cell proliferation and apoptosis. Prostatic smooth muscle cells contract under adrenergic control. The response of a cell to stretch may have a role in the pathogenesis of BPH. MATERIALS AND METHODS Monolayer cultures of human prostatic stromal and epithelial cell lines were exposed to cyclic stretch for 48 hours. RESULTS Cyclic stretch conferred resistance to etoposide induced apoptosis. Underlying this apoptotic resistance was increased expression of the anti-apoptotic Bcl-2 family of proteins. As measured by thymidine incorporation, the rate of proliferation also increased in benign epithelial cells under cyclic stretch conditions. Furthermore, an increase in the production of platelet-derived growth factor by stromal cells and transforming growth factor-beta by epithelial cells occurred under such conditions. CONCLUSIONS The observed changes in proliferation and apoptosis may contribute to the understanding of BPH, ultimately leading to therapeutic and preventive applications.

Insulin-like growth factor-1 alters apoptotic signalling in prostate cancer.

Serum insulin-like growth factor-1 (IGF-1) levels have been correlated with an increased risk of developing prostate cancer.1 The progression from androgendependent to androgen-independent prostate cancer is thought to be due to survival factors inducing apoptotic resistance in these cells. IGF-1 may represent a novel survival factor in prostate cancer. Over-expression of focal adhesion kinase (FAK) and anti-apoptotic proteins correlates with an increased metastatic phenotype.2 The aim of this study was to determine if IGF-1 alters prostate cancer cell resistance to chemical and radiation induced apoptosis, and to examine the intracellular signalling mechanisms involved.

Caspase protease manipulation: a novel approach to apoptotic induction in prostate cancer

Human prostate carcinomas initially regress after androgen ablation, but can eventually relapse into a hormoneindependent phenotype resistant to apoptosis. This resistance is associated with increased expression of antiapoptotic proteins such as Bcl-2. Caspase proteases have been described as the central executioners of cell death. Their cleavage from the inactive pro-form to their active enzyme is a critical step in most types of apoptosis. We hypothesize that altered expression of pro-caspases may also contribute to prostate cancer resistance to apoptosis, and the mechanisms regulating expression of these caspases may have important implications in inducing or priming these cells for apoptosis. Diethylmaleate (DEM), a thiol-depleting agent, can induce apoptosis in both androgen-sensitive and insensitive prostate cancer cell lines which are caspase-3 dependent. These studies aimed to determine if there is an alteration in pro-caspase 3 expression in normal, benign and malignant archived prostate sections and to investigate the role of DEM in increasing pro-caspase expression and apoptotic potential in prostate cancer cells.

Effects of the dual 5 alpha reductase inhibitor dutasteride on apoptosis in primary cultures of prostate cancer epithelial cells

BACKGROUND The profound reduction in serum dihydrotestosterone (DHT) observed with the dual 5 alpha-reductase inhibitor (5ARI) dutasteride makes it an attractive agent for prostate cancer therapy. The objective of the current study was to determine whether dutasteride would induce apoptosis in a range of prostate epithelial cell lines and primary cultures. METHODS Both human prostate androgen-sensitive cell lines (PwR-1E, PNT-2, LNCaP, and PC3[AR2]) and an androgen-independent cell line (PC-3) were grown to confluence. Primary epithelial cells extracted from fresh prostate cancer radical prostatectomy specimens also were grown to confluence under optimal conditions. Total cellular protein was extracted to confirm cytokeratin 18 and antihuman alpha-methylacyl-CoA racemase (AMACR) expression of the primary cells. Apoptosis was assessed by propidium iodide DNA staining and flow cytometry after 24 hours of culture in from 0 microM to 10 microM of dutasteride. RESULTS Dutasteride induced a dose-dependent increase in apoptosis in the androgen-sensitive prostate cell lines PwR-1E, PNT-2, and LNCaP and in the androgen receptor-expressing PC3(AR2) cell line. However, there was no significant apoptosis noted in the parental PC-3 cells. Of 16 primary epithelial cultures that were treated, 7 cultures were induced to undergo apoptosis, and 9 cultures were unresponsive. All primary cultures were positive for cytokeratin 18 expression, confirming their epithelial phenotype. Responder epithelial cells were positive for AMACR expression. CONCLUSIONS The results of the current study confirmed that dutasteride differentially induced apoptosis in a subset of prostate cell lines and primary prostate epithelial cells. Understanding the cellular phenotype may indicate susceptible cells.

Hypoxid inhibits proliferation in human bladder smooth muscle cells

ConclusionIn summary, this study demonstrates for the first time that hypoxia inhibits bladder smooth muscle proliferation, yet stimulates angiogenesis through increased VEGF production. Although the cells remain viable, this anti-proliferative effect may play a role in the development of bladder decompensation.