Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho - Centro de Ciências da Saúde C1-042, Universidade Federal do Rio de Janeiro; Av. Carlos Chagas Filho 373 - Cidade Universitária, CEP 21941-902, Rio de Janeiro/RJ, Brazil
Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho - Centro de Ciências da Saúde C1-042, Universidade Federal do Rio de Janeiro; Av. Carlos Chagas Filho 373 - Cidade Universitária, CEP 21941-902, Rio de Janeiro/RJ, Brazil.
J Biol Chem. 2020 May 8;295(19):6457-6471. doi: 10.1074/jbc.RA120.013090. Epub 2020 Mar 30.
Multidrug resistance (MDR) in cancer arises from cross-resistance to structurally- and functionally-divergent chemotherapeutic drugs. In particular, MDR is characterized by increased expression and activity of ATP-binding cassette (ABC) superfamily transporters. Sphingolipids are substrates of ABC proteins in cell signaling, membrane biosynthesis, and inflammation, for example, and their products can favor cancer progression. Glucosylceramide (GlcCer) is a ubiquitous glycosphingolipid (GSL) generated by glucosylceramide synthase, a key regulatory enzyme encoded by the UDP-glucose ceramide glucosyltransferase () gene. Stressed cells increase biosynthesis of ceramides, which return to sub-toxic levels after UGCG mediates incorporation into GlcCer. Given that cancer cells seem to mobilize UGCG and have increased GSL content for ceramide clearance, which ultimately contributes to chemotherapy failure, here we investigated how inhibition of GSL biosynthesis affects the MDR phenotype of chronic myeloid leukemias. We found that MDR is associated with higher UGCG expression and with a complex GSL profile. UGCG inhibition with the ceramide analog d-threo-1-(3,4,-ethylenedioxy)phenyl-2-palmitoylamino-3-pyrrolidino-1-propanol (EtDO-P4) greatly reduced GSL and monosialotetrahexosylganglioside levels, and co-treatment with standard chemotherapeutics sensitized cells to mitochondrial membrane potential loss and apoptosis. ABC subfamily B member 1 (ABCB1) expression was reduced, and ABCC-mediated efflux activity was modulated by competition with nonglycosylated ceramides. Consistently, inhibition of ABCC-mediated transport reduced the efflux of exogenous C-ceramide. Overall, UGCG inhibition impaired the malignant glycophenotype of MDR leukemias, which typically overcomes drug resistance through distinct mechanisms. This work sheds light on the involvement of GSL in chemotherapy failure, and its findings suggest that targeted GSL modulation could help manage MDR leukemias.
多药耐药性 (MDR) 在癌症中是由于对结构和功能上不同的化疗药物产生交叉耐药性而产生的。特别是，MDR 的特征是 ATP 结合盒 (ABC) 超家族转运蛋白的表达和活性增加。例如，神经酰胺是细胞信号转导、膜生物合成和炎症中 ABC 蛋白的底物，其产物可以促进癌症进展。葡萄糖脑苷脂 (GlcCer) 是一种普遍存在的糖脂 (GSL)，由葡萄糖脑苷脂合酶生成，葡萄糖脑苷脂合酶是由 UDP-葡萄糖神经酰胺葡萄糖基转移酶 () 基因编码的关键调节酶。应激细胞增加神经酰胺的生物合成，然后 UGCG 将其掺入 GlcCer 后，神经酰胺回到亚毒性水平。鉴于癌细胞似乎动员 UGCG 并增加 GSL 含量以清除神经酰胺，这最终导致化疗失败，因此我们研究了抑制 GSL 生物合成如何影响慢性髓性白血病的 MDR 表型。我们发现 MDR 与 UGCG 表达升高和复杂的 GSL 谱有关。用神经酰胺类似物 d-threo-1-(3,4,-ethylenedioxy)phenyl-2-palmitoylamino-3-pyrrolidino-1-propanol (EtDO-P4) 抑制 UGCG 极大地降低了 GSL 和单唾液酸四己糖神经节苷脂的水平，并且与标准化疗药物联合治疗使细胞对线粒体膜电位丧失和凋亡敏感。ABC 亚家族 B 成员 1 (ABCB1) 的表达减少，并且 ABCC 介导的外排活性通过与非糖基化神经酰胺竞争而被调节。一致地，抑制 ABCC 介导的转运减少了外源性 C-神经酰胺的外排。总体而言，UGCG 抑制破坏了 MDR 白血病的恶性糖表型，MDR 白血病通常通过不同的机制克服耐药性。这项工作揭示了 GSL 在化疗失败中的参与，其研究结果表明，靶向 GSL 调节可能有助于管理 MDR 白血病。
