Discovery of highly potent acid ceramidase inhibitors with in vitro tumor chemosensitizing activity

Abstract

The expression of acid ceramidase (AC) – a cysteine amidase that hydrolyses the proapoptotic lipid ceramide – is abnormally high in several human tumors, which is suggestive of a role in chemoresistance. Available AC inhibitors lack, however, the potency and drug-likeness necessary to test this idea. Here we show that the antineoplastic drug carmofur, which is used in the clinic to treat colorectal cancers, is a potent AC inhibitor and that this property is essential to its anti-proliferative effects. Modifications in the chemical scaffold of carmofur yield new AC inhibitors that act synergistically with standard antitumoral drugs to prevent cancer cell proliferation. These findings identify AC as an unexpected target for carmofur, and suggest that this molecule can be used as starting point for the design of novel chemosensitizing agents.

Acid ceramidase is a novel drug target for pediatric brain tumors

“…Treating cultures of SJGMB2 cells with 50 μM carmofur resulted in intracellular accumulation of various ceramide species, which were identified and quantified by liquid chromatography and mass spectrometry (Figure 6 ). This finding, which is in consistent with other study [ 10 ], suggests that carmofur inhibits ASAH1 activity and elevates tissue ceramide levels.…”

Acid ceramidase is a novel drug target for pediatric brain tumors

“…Treating cultures of SJGMB2 cells with 50 μM carmofur resulted in intracellular accumulation of various ceramide species, which were identified and quantified by liquid chromatography and mass spectrometry (Figure 6 ). This finding, which is in consistent with other study [ 10 ], suggests that carmofur inhibits ASAH1 activity and elevates tissue ceramide levels.…”

Discovery of New Acid Ceramidase-Targeted Acyclic 5-Alkynyl and 5-Heteroaryl Uracil Nucleosides

“…Since sphingosine kinase 1 (SK1) and acid ceramidase 1 (ASAH1) were recently recognized as novel targets for intervention with antibreast agents, we have assessed the effect of potent cytostatic compounds 6 , 8 , 9c , and 9e on SK1 and ASAH1 expression in MCF-7 breast cancer cells. Acyclonucleosides 6 , 8 , 9c , and 9e can be considered as structural analogs of antineoplastic drug carmofur (Figure ), that was identified as a highly potent inhibitor of intracellular ASAH1 activity . While compounds 6 , 8 , 9c , and 9e contain a PCV-like side chain, carmfour is an acyclic 5-fluorouracil analog bearing 1-hexylcarbamoyl at N-1.…”

Complete Acid Ceramidase ablation prevents cancer-initiating cell formation in melanoma cells

“…As expected from prior work 19 , AC ablation causes substantial changes in the cellular sphingolipidome. We found that ASAH1 -null cells accumulate abnormally high levels of ceramides that are preferred substrates for AC (C14:0, C16:0 and C18:0).…”

Acid ceramidase is a novel drug target for pediatric brain tumors

“…Treating cultures of SJGMB2 cells with 50 μM carmofur resulted in intracellular accumulation of various ceramide species, which were identified and quantified by liquid chromatography and mass spectrometry (Figure 6 ). This finding, which is in consistent with other study [ 10 ], suggests that carmofur inhibits ASAH1 activity and elevates tissue ceramide levels.…”

Discovery of New Acid Ceramidase-Targeted Acyclic 5-Alkynyl and 5-Heteroaryl Uracil Nucleosides

“…Since sphingosine kinase 1 (SK1) and acid ceramidase 1 (ASAH1) were recently recognized as novel targets for intervention with antibreast agents, we have assessed the effect of potent cytostatic compounds 6 , 8 , 9c , and 9e on SK1 and ASAH1 expression in MCF-7 breast cancer cells. Acyclonucleosides 6 , 8 , 9c , and 9e can be considered as structural analogs of antineoplastic drug carmofur (Figure ), that was identified as a highly potent inhibitor of intracellular ASAH1 activity . While compounds 6 , 8 , 9c , and 9e contain a PCV-like side chain, carmfour is an acyclic 5-fluorouracil analog bearing 1-hexylcarbamoyl at N-1.…”

Complete Acid Ceramidase ablation prevents cancer-initiating cell formation in melanoma cells

“…As expected from prior work 19 , AC ablation causes substantial changes in the cellular sphingolipidome. We found that ASAH1 -null cells accumulate abnormally high levels of ceramides that are preferred substrates for AC (C14:0, C16:0 and C18:0).…”

Acid ceramidase is a novel drug target for pediatric brain tumors

“…Treating cultures of SJGMB2 cells with 50 μM carmofur resulted in intracellular accumulation of various ceramide species, which were identified and quantified by liquid chromatography and mass spectrometry (Figure 6 ). This finding, which is in consistent with other study [ 10 ], suggests that carmofur inhibits ASAH1 activity and elevates tissue ceramide levels.…”

Discovery of New Acid Ceramidase-Targeted Acyclic 5-Alkynyl and 5-Heteroaryl Uracil Nucleosides

“…Since sphingosine kinase 1 (SK1) and acid ceramidase 1 (ASAH1) were recently recognized as novel targets for intervention with antibreast agents, we have assessed the effect of potent cytostatic compounds 6 , 8 , 9c , and 9e on SK1 and ASAH1 expression in MCF-7 breast cancer cells. Acyclonucleosides 6 , 8 , 9c , and 9e can be considered as structural analogs of antineoplastic drug carmofur (Figure ), that was identified as a highly potent inhibitor of intracellular ASAH1 activity . While compounds 6 , 8 , 9c , and 9e contain a PCV-like side chain, carmfour is an acyclic 5-fluorouracil analog bearing 1-hexylcarbamoyl at N-1.…”

Complete Acid Ceramidase ablation prevents cancer-initiating cell formation in melanoma cells

“…As expected from prior work 19 , AC ablation causes substantial changes in the cellular sphingolipidome. We found that ASAH1 -null cells accumulate abnormally high levels of ceramides that are preferred substrates for AC (C14:0, C16:0 and C18:0).…”