Aoyama Yuka, Sobue Sayaka, Mizutani Naoki, Inoue Chisato, Kawamoto Yoshiyuki, Nishizawa Yuji, Ichihara Masatoshi, Kyogashima Mamoru, Suzuki Motoshi, Nozawa Yoshinoti, Murate Takashi
College of Life and Health Sciences, Chubu University, Kasugai, 487-8501, Japan.
Division of Molecular Carcinogenesis, Nagoya University Graduate School of Medicine, Nagoya, 466-0064, Japan.
Biochem Biophys Res Commun. 2017 Apr 29;486(2):551-557. doi: 10.1016/j.bbrc.2017.03.084. Epub 2017 Mar 18.
Taxoids are anti-cancer drugs frequently used to treat solid tumors, but they are sometimes ineffective and tumors may become resistant to their action. Here, we examined the involvement of sphingolipid metabolic enzymes in paclitaxel (PTX) resistance using a human prostate cancer cell line, PC3, and its PTX-resistant subline, PC3-PR. PTX (20 nM) suppressed cell proliferation and increased various ceramide species in PC3, but not PC3-PR, cells. PC3-PR contained higher S1P levels than did PC3, regardless of PTX treatment. Western blotting revealed that PC3-PR cells expressed higher levels of sphingosine kinase 1 (SPHK1) and glucosylceramide synthase (GCS) but lower levels of acid sphingomyelinase (ASMase) and neutral sphingomyelinase 2 than did PC3 cells. Inhibition of SPHK1 using siRNA or a pharmacological inhibitor decreased S1P levels in PC3-PR cells and inhibited proliferation in the presence or absence of PTX, suggesting that SPHK1 is at least partially responsible for PTX resistance. Similarly, GCS inhibitors (PDMP and PPMP) increased cellular ceramides and suppressed the proliferation of PC3-PR. However, inhibition of proteasome function or histone deacetylase activity increased SMase and ceramide levels and suppressed PC3-PR proliferation. These results suggest that modulation of metabolic enzyme expression and alteration of the sphingolipid rheostat protects cancer cells against PTX.
紫杉烷类是常用于治疗实体瘤的抗癌药物，但它们有时会无效，而且肿瘤可能会对其作用产生耐药性。在此，我们使用人前列腺癌细胞系PC3及其耐紫杉醇亚系PC3-PR，研究了鞘脂代谢酶在紫杉醇（PTX）耐药中的作用。PTX（20 nM）抑制PC3细胞的增殖并增加多种神经酰胺种类，但对PC3-PR细胞无效。无论是否进行PTX处理，PC3-PR细胞中的S1P水平均高于PC3细胞。蛋白质印迹分析显示，与PC3细胞相比，PC3-PR细胞中鞘氨醇激酶1（SPHK1）和葡萄糖神经酰胺合酶（GCS）的表达水平较高，而酸性鞘磷脂酶（ASMase）和中性鞘磷脂酶2的表达水平较低。使用小干扰RNA（siRNA）或药物抑制剂抑制SPHK1可降低PC3-PR细胞中的S1P水平，并在有或无PTX的情况下抑制细胞增殖，这表明SPHK1至少部分地导致了PTX耐药。同样，GCS抑制剂（PDMP和PPMP）可增加细胞内神经酰胺水平并抑制PC3-PR细胞的增殖。然而，抑制蛋白酶体功能或组蛋白脱乙酰酶活性可增加鞘磷脂酶和神经酰胺水平，并抑制PC3-PR细胞的增殖。这些结果表明，代谢酶表达的调节和鞘脂变阻器的改变可保护癌细胞免受PTX的影响。
