Differential Regulation of Specific Sphingolipids in Colon Cancer Cells during Staurosporine-Induced Apoptosis

Abstract

Apoptosis is accompanied by distinct morphological changes at the plasma and organelle membrane level. Involvement of certain lipids in apoptosis has been established; however, we have limited understanding of the specific lipid structures that participate in this process. We used untargeted comparative lipidomics to study the changes in lipid composition during staurosporine-induced apoptosis in HCT-116. Our results revealed that ceramides, dihydroceramides, and sphingomyelins, with defined acyl chains, constitute the majority of changes in the lipidome. Expression levels and activities of enzymes responsible for the biosynthesis of lipids that change suggest that de novo synthesis causes these specific changes. Further analysis of the lipidome during apoptosis in other cancer and non-cancer cell lines suggested that accumulation of ceramides and dihydroceramides is specific to cancer cells. Taken together, our data propose that these molecules are regulated at the lipid-specific level during apoptosis and that this regulation differs between cancer and non-cancer cells.

Staurosporines decrease ORMDL proteins and enhance sphingomyelin synthesis resulting in depletion of plasmalemmal phosphatidylserine

“…reported that sphingolipid mass increases during STS-induced apoptosis, especially in cancer cell lines47. In this study, treatment of human colorectal carcinoma cells with a comparatively high concentration of STS (300 nM) increased the mass of not only sphingomyelin but also dihydroceramide and ceramide47. Under these conditions, an increase in the expression of the ceramide synthases and a decrease in sphingomyelinase activity is seen.…”

Untargeted Lipidomics Highlight the Depletion of Deoxyceramides during Therapy‐Induced Senescence

“…We followed similar lipidomics workflow as how we described in the past for sample preparation, data acquisition, and analysis. [ 8,11,20 ] Briefly, five biological replicates of proliferating and senescent cells were analyzed in positive and negative electrospray ionization modes. Peak alignment based on mass‐to‐charge ratio ( m / z ), grouping of different adducts, retention time, and isotopic ratio was carried out in Profinder (Agilent Technologies).…”

“…LC‐MS analysis was performed as described previously. [ 8,11,20 ] Briefly, LC‐MS data acquisition was performed using an Agilent 1260 HPLC paired with an Agilent 6530 Accurate‐Mass Quadrupole Time‐of‐Flight mass spectrometer (Agilent Technologies, Santa Clara, CA). Prior to analysis, separation was achieved with reverse phase chromatography.…”

“…Lipids have been shown to play key roles in other cellular processes including cell division, [ 8 ] survival, [ 9 ] and cell death, [ 10‐12 ] both as important structural and signaling molecules. A previous study showed that lipid metabolism and oxidation are upregulated during senescence, suggesting that lipid‐induced toxicity might play a role during this process.…”

Emerging roles for lipids in non-apoptotic cell death

“…Thus, treatment of cells with the saturated fatty acid (SFA) palmitate (16 : 0, annotations herein refer to the number of carbon atoms and points of unsaturation) can trigger apoptosis by causing endoplasmic reticulum (ER) stress, 15 while ceramide (a sphingolipid; Figure 1a) accumulates in cancer cells exposed to pro-apoptotic signals (e.g., ultraviolet irradiation, the small molecule staurosporine) and has an enigmatic role in transducing this signal, perhaps by damaging intracellular membranes or the plasma membrane. 16, 17, 18 Second, lipids have important accessory roles in the execution of apoptosis. For example, in the intrinsic apoptosis pathway, oligomerization of the pore-forming BH3 family members BCL2-associated X protein (BAX) and BCL2-antagonist/killer 1 (BAK) on the mitochondrial outer membrane requires the lipids sphingosine-1-phosphate and hexadecenal as specific cofactors.…”