Gentamicin Targets Acid Sphingomyelinase in Cancer: The Case of the Human Gastric Cancer NCI-N87 Cells

Abstract

Emerging literature implicates acid sphingomyelinase in tumor sensitivity/resistance to anticancer treatments. Gentamicin is a drug commonly used as an antimicrobial but its serendipity effects have been shown. Even though many evidences on the role of gentamicin in cancer have been reported, its mechanism of action is poorly understood. Here, we explored acid sphingomyelinase as a possible new target of gentamicin in cancer. Since gastric cancer is one of the most common cancers and represents the second cause of death in the world, we performed the study in NCI-N87 gastric cancer cell line. The effect of the drug resulted in the inhibition of cell proliferation, including a reduction of cell number and viability, in the decrease of MIB-1 proliferative index as well as in the upregulation of cyclin-dependent kinase inhibitor 1A and 1B (CDKN1A and CDKN1B), and growth arrest and DNA-damage 45A (GADD45A) genes. The cytotoxicity was apoptotic as shown by FACS analysis. Additionally, gentamicin reduced HER2 protein, indicating a minor tumor aggressiveness. To further define the involvement of sphingomyelin metabolism in the response to the drug, gene and protein expression of acid and neutral sphingomeylinase was analyzed in comparison with phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and vitamin D receptor (VDR), molecules involved in cancer. Gentamicin induced a downregulation of PTEN, VDR, and neutral sphingomyelinase and a strong upregulation of acid sphingomyelinase. Of note, we identified the same upregulation of acid sphingomyelinase upon gentamicin treatment in other cancer cells and not in normal cells. These findings provide new insights into acid sphingomyelinase as therapeutic target, reinforcing studies on the potential role of gentamicin in anticancer therapy.

Vitamin D3 Enriches Ceramide Content in Exosomes Released by Embryonic Hippocampal Cells

“…In order to test whether physiological concentration of VD3 (100 nmol/L), previously used to induce HN9.10 cell differentiation [16,17] was the better concentration, we first set out to study the dose-dependent effect of VD3 on HN9.10 cell viability after 24 h of culture by using MTT assay. The results demonstrated that VD3 from 25 nmol/L to 300 nmol/L concentration did not induce damage in the cells, indicating that it is not a cytotoxic substance; 1% and 2% DMSO were used as positive controls.…”

Cholesterol and Sphingolipid Enriched Lipid Rafts as Therapeutic Targets in Cancer

“…Interestingly, the breakdown of sphingomyelin, due to the action of both acid and neutral sphingomyelinases, with the consequent production of different species of ceramides, is involved in the apoptosis of cancer cells. Notably, ingastric cancer cells gentamicin stimulates acid sphingomyelinase [ 22 ] and vitamin D3 neutral sphingomyelinase [ 23 ]. Moreover, vitamin D3 reduces glioblastoma cell aggressivenessvia neutral sphingomyelinase [ 24 ].…”

Exploring Sphingolipid Implications in Neurodegeneration

“…The SM breakdown is carried out by different SMase isoenzymes belonging to three families classified based on their activity pH optima into acid, and neutral subtypes: aSMase and nSMase (2). aSMase that is specifically located in lysosomes and under stress conditions, rapidly translocates from lysosomes to the outer leaflet of the plasma membrane (2). An array of nSMases reside in specific subcellular structures, including cell nucleus (3).…”