Bcl‐2 overexpression prevents apoptosis induced by ceramidase inhibitors in malignant melanoma and HaCaT keratinocytes

Abstract

We examined the biological effects of the ceramide analogues (1S,2R)-2-N-myristoylamino-1-phenyl-1-propanol (De-MAPP) and (1R,2R)-2-N-myristoylamino-1-(4-nitrophenyl)-1,3-propandiol (D-NMAPPD) on human HaCaT keratinocytes and human melanoma cells. We could demonstrate that D-e-MAPP and D-NMAPPD are able to suppress acid ceramidase activity. The elevation of the endogenous level of ceramide is followed by induction of apoptosis and suppression of proliferation in HaCaT keratinocytes. Moreover, we recently identified a group of human melanoma cell populations which are heterogeneously susceptible to C 2 -ceramide-mediated apoptosis. Studies with these melanoma cells revealed correlation between ceramide-mediated apoptosis and D-NMAPPD-induced apoptosis, confirming the effect of this inhibitor on ceramide signaling in human melanoma cells. These findings suggest ceramidase inhibitors as a potential new therapeutical class of antiproliferative and cytostatic drugs. ß

Sphingosine kinase activity counteracts ceramide-mediated cell death in human melanoma cells: role of Bcl-2 expression

“…Bro-Tet-On cells transfected with a Bcl-2 expression vector under the control of the Tet promoter showed increased Bcl-2 expression after 8 and 24 h of doxycycline induction (Figure 7d). In agreement with other reports (Zhang et al, 1996;Raisova et al, 2002), induction of Bcl-2 in these melanoma cells significantly decreased apoptosis induced by C 6 -ceramide and CH-11 as compared to vector-transfected cells (Figure 7a and b). In parallel with increased Bcl-2 expression, there was an increase in SphK1 expression (Figure 7d).…”

“…After 2-3 weeks, green cells were sorted with an EPICS 753 argon laser flow cytometer (Beckman Coulter Epics Elite). The construction of the mouse Bcl-2 expression plasmid based on pIRES (Clontech) has been reported previously and has been shown to be functional in A-375 cells (Raisova et al, 2002). Tetracycline/doxycycline-inducible BroTet-On melanoma cells have been described previously .…”

Overcoming resistance to γ-rays in squamous carcinoma cells by poly-drug elevation of ceramide levels

“…The advantage of combining several drugs that interfere with the endogenous ceramide pathway, rather than blocking one specific pathway (Raisova et al, 2002) or adding short-chain exogenous ceramide (Sugiki et al, 2000), should be in reducing the concentration of potentially toxic chemical agents and blocking different metabolic routes only partially. The separate addition of these compounds did not generate ceramide release or apoptotic death in either cellular model, as previously described in lymphoid cell lines .…”

“…For instance, Chmura et al (1997a) reversed the radioresistance of the SQ20B tumour model in vitro and in vivo by increasing sphingomyelinase activity by the addition of chelerythrine. Raisova et al (2002) increased the ceramide content and induced apoptosis in HaCaT keratinocytes and human melanoma cells by the addition of a ceramidase inhibitor.…”

The natural marine anhydrophytosphingosine, Jaspine B, induces apoptosis in melanoma cells by interfering with ceramide metabolism

“…In human melanoma cell lines, resistance to stress-induced apoptosis has been associated with low ceramide levels and, conversely, high sphingosine-1-phosphate levels and sphingosine kinase activity [7]. On the contrary, treatment with a ceramidase inhibitor was shown to 4 increase ceramide content and elicit apoptosis [8]. As elevations in ceramide levels promote apoptosis in melanoma cells, the hypothesis that related analogs of ceramide could be used as chemotherapeutic agents has been proposed.…”