Distinct effects of ceramide‐generating pathways in prostate adenocarcinoma cells

Abstract

1 Ceramide, generated by the hydrolysis of sphingomyelin, mediates the actions of several cytokines such as tumour necrosis factor-a (TNF-a) interferon-g and interleukin-1b (IL-1b), including their inhibitory e ect on tumour proliferation. We have evaluated the role of ceramide in the proliferation of prostate cancer by using the human prostate adenocarcinoma LNCaP cell line. 2 Treatment of LNCaP cells with neutral or acidic sphingomyelinase or addition of C8-or C2-ceramide, two cell permeable analogues of endogenous ceramide, induced a profound inhibition of cell proliferation. This e ect appeared after 24 h, was still present after 72 h of exposure to the drugs and exhibited concentration-dependency (10 ± 200 and 5 ± 200 mU ml 71 for neutral and acidic sphingomyelinase, respectively, and 1 ± 25 mM for C8-ceramide). 3 The inhibitory e ect on cell growth caused by neutral sphingomyelinase and ceramides was rapidly reversible as LNCaP cells rapidly regained their previous proliferation rate following withdrawal of the treatment. 4 IL-1b produced profound inhibition of LNCaP cell proliferation and caused enhanced ceramide formation. 5 No clear features of apoptotic cell death were detectable by either oligonucleosome formation, cyto¯uorimetric analysis or nuclear staining following exposure of LNCaP cells to neutral sphingomyelinase, ceramide or IL-1b. However, clear changes in LNCaP cell cycle distribution were detectable following these treatments. In contrast, treatment with acidic sphingomyelinase or TNF-a induced apoptotic death detectable by¯ow cytometric analysis and bisbenzimide staining. 6 In conclusion, our data demonstrate that preferential activation of distinct enzymatic pathways by cytokines may lead to di erent outcomes in the viability of LNCaP cells.

Biomodulatory role of ceramide in basic fibroblast growth factor-induced proliferation of cerebellar astrocytes in primary culture

“…This result concurs with the controversy concerning the effect of exogenous ceramide on cell growth, either promoting (Olivera et al, 1992;Chan and Ochi, 1995) or inhibitory (Borchardt et al, 1994;Dbaibo et al, 1995;Gómez-Muñ oz et al, 1995;Geilen et al, 1996;Condorelli et al, 1999), and the mitogenic effect of the same growth factor that is inhibited (Liu and Anderson, 1995;Coroneos et al, 1996) or potentiated (Sasaki et al, 1995) by exogenous ceramide. It appears very likely that the target cell of the growth stimulus is the major determinant to the functional role of ceramide in growth modulation.…”

“…This result supports the notion that an inverse relationship exists between ceramide levels and cell proliferation (Borchardt et al, 1994;Dbaibo et al, 1995;Jayadev et al, 1995;Geilen et al, 1996;Condorelli et al, 1999), against the claim that a transient increase in ceramide levels occurs in the early (Augé et al, 1996) or late (Lee et al, 1998) stages of growth stimulation.…”

Connexin43 increases the sensitivity of prostate cancer cells to TNFα-induced apoptosis

“…Consistently, we found no effects of TNF␣ (at concentrations as high as 100 ng/ml) upon PC3 cells. LNCaP cells are also relatively resistant to TNF␣; typically, concentrations of at least 10-20 ng/ml have been required to see any evidence of apoptosis (Condorelli et al, 1999;Kulik et al, 2001;Lee et al, 2003). We found little TNF␣-induced cytotoxicity in LNCaP cells (uninfected or infected with control adenovirus).…”

Vitamin D–induced up–regulation of tumour necrosis factor alpha (TNF–α) in prostate cancer cells

“…These cytokines not only modulate immune response, but also regulate the functions of various cell types including cancer cells. TNF-a, IL-1 and IL-6 exert cytotoxic action and can cause cell growth inhibition and apoptosis in prostate cancer cells (Culig et al, 1998;Hoosein, 1998;Levesque et al, 1998;Chiao et al, 1999;Condorelli et al, 1999;Kawada et al, 1999). TNF-a, IL-1, IL-6 and their receptors are expressed in prostate cancer (Siegall et al, 1990;Okamoto et al, 1997;Hoosein, 1998;Giri and Ittmann, 2000).…”