Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA.
Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA.
Anticancer Res. 2012 Jul;32(7):2479-2485.
The effectiveness of photodynamic therapy (PDT) for cancer treatment correlates with apoptosis. We previously observed that the knockdown of ceramide synthase 6, an enzyme from the de novo sphingolipid biosynthesis pathway, is associated with marked reduction in C18-dihydroceramide and makes cells resistant to apoptosis post-PDT. Down-regulation of ceramide synthase 1 (CERS1) can also render cells resistant to anticancer drugs.
To explore the impact of CERS1 knockdown on apoptosis and the sphingolipid profile, post-PDT, with the silicone phthalocyanine Pc 4, in a human head and neck squamous carcinoma cell line.
Besides siRNA transfection and PDT treatment, the following methods were used: immunoblotting for protein expression, mass spectrometry for sphingolipid analysis, spectroflurometry and flow cytometry for apoptosis detection, and trypan blue assay for cell viability evaluation.
CERS1 knockdown led to inhibition of PDT-induced caspase 3-like (DEVDase) activation, of apoptosis and cell death. CERS1 knockdown was associated with global and selective decreases in ceramides and dihydroceramides, in particular C18-, C18:1- and C20-ceramide post-PDT.
Our novel findings are consistent with the notion that CERS1 regulates apoptotic resistance to PDT, partly via C18- and C20-ceramide, and that CERS1 is a molecular target for controlling resistance to PDT.
光动力疗法（PDT）治疗癌症的效果与细胞凋亡有关。我们之前观察到，从头合成鞘脂生物合成途径的酶——神经酰胺合酶 6 的敲低与 C18-二氢神经酰胺的显著减少有关，并使细胞对 PDT 后凋亡产生抗性。神经酰胺合酶 1（CERS1）的下调也可以使细胞对抗癌药物产生抗性。
探讨 CERS1 敲低对人头颈鳞癌细胞系经硅酞菁 Pc 4 介导的 PDT 后细胞凋亡和鞘脂谱的影响。
除了 siRNA 转染和 PDT 处理外，还使用了以下方法：蛋白表达的免疫印迹、鞘脂分析的质谱、凋亡检测的荧光光度法和流式细胞术以及台盼蓝测定法评估细胞活力。
CERS1 敲低导致 PDT 诱导的半胱天冬酶 3 样（DEVDase）活性、凋亡和细胞死亡的抑制。CERS1 敲低与鞘脂和二氢神经酰胺的全局和选择性降低有关，特别是 C18-、C18:1-和 C20-神经酰胺在 PDT 后。
我们的新发现与以下观点一致，即 CERS1 通过 C18-和 C20-神经酰胺调节对 PDT 的凋亡抵抗，并且 CERS1 是控制对 PDT 抵抗的分子靶标。
