Lysosomal membrane permeabilization is an early event in Sigma-2 receptor ligand mediated cell death in pancreatic cancer.
Lysosomal membrane permeabilization is an early event in Sigma-2 receptor ligand mediated cell death in pancreatic cancer.
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DOI：
10.1186/1756-9966-31-41
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发表时间：
2012-05-02
期刊：
影响因子：
--
通讯作者：
Hawkins WG
中科院分区：
文献类型：
--
作者：
Hornick JR;Vangveravong S;Spitzer D;Abate C;Berardi F;Goedegebuure P;Mach RH;Hawkins WG
Sigma-2受体配体已被研究用于治疗胰腺癌，因为它们优先被增殖的细胞内化并诱导细胞凋亡。对细胞凋亡的这种机制知之甚少，关于caspase-3依赖的报道各不相同。在这项研究中，我们评估了多个sigma-2受体配体，每个配体都显示出在人类胰腺癌临床前模型中减轻肿瘤负担。两类荧光标记的Sigma-2受体配体(SW43和PB282的衍生物)定位于Bxpc3和Aspc1胰腺癌细胞的细胞膜成分，并聚集在溶酶体中。我们发现，溶酶体中的相互作用是Sigma-2配体处理后细胞死亡的关键，因为选择性地抑制具有保护作用的溶酶体膜糖蛋白LAMP1与shRNA一起极大地降低了处理后细胞的活力。Sigma-2配体诱导溶酶体膜通透性(LMP)和蛋白酶易位，触发下游的细胞凋亡效应。随后，SW43处理后细胞的氧化应激大大增加，亲水性抗氧化剂N-乙酰半胱氨酸(N-乙酰半胱氨酸)比亲脂性抗氧化剂α-生育酚(α-TOCO)对此有更大的保护作用。相反，PB282介导的细胞毒性较少依赖于细胞氧化，尽管α-TOCO确实提供了对该配体的保护。此外，我们还发现，组织蛋白酶抑制剂对caspase-3诱导的抑制作用不如抗氧化剂显著。Nac和α-toco对pB282诱导的caspase-3均有保护作用，而只有Nac对SW43处理有保护作用。Caspase-3抑制剂DEVD-FMK对PB282有显著的保护作用，但对SW43没有保护作用。Sigma-2配体SW43通过参与LMP和氧化应激的caspase非依赖性过程使胰腺癌细胞死亡，NAC保护其免受氧化应激的影响。然而，在DEVD-FMK和α-TOCO保护下，PB282经历了半胱氨酸酶依赖的死亡，LMP也被认为在凋亡刺激下稳定线粒体膜。这些机制上的差异可能取决于化合物的结构类别与固有的sigma-2结合亲和力。随着胰腺癌对化疗产生的特定凋亡刺激的耐药性得到更好的认识，以及患者量身定做的治疗变得更加可行，应该根据对凋亡途径的敏感性来选择具有高Sigma-2受体亲和力的配体。
Sigma-2 receptor ligands have been studied for treatment of pancreatic cancer because they are preferentially internalized by proliferating cells and induce apoptosis. This mechanism of apoptosis is poorly understood, with varying reports of caspase-3 dependence. We evaluated multiple sigma-2 receptor ligands in this study, each shown to decrease tumor burden in preclinical models of human pancreatic cancer. Fluorescently labeled sigma-2 receptor ligands of two classes (derivatives of SW43 and PB282) localize to cell membrane components in Bxpc3 and Aspc1 pancreatic cancer cells and accumulate in lysosomes. We found that interactions in the lysosome are critical for cell death following sigma-2 ligand treatment because selective inhibition of a protective lysosomal membrane glycoprotein, LAMP1, with shRNA greatly reduced the viability of cells following treatment. Sigma-2 ligands induced lysosomal membrane permeabilization (LMP) and protease translocation triggering downstream effectors of apoptosis. Subsequently, cellular oxidative stress was greatly increased following treatment with SW43, and the hydrophilic antioxidant N-acetylcysteine (NAC) gave greater protection against this than a lipophilic antioxidant, α-tocopherol (α-toco). Conversely, PB282-mediated cytotoxicity relied less on cellular oxidation, even though α-toco did provide protection from this ligand. In addition, we found that caspase-3 induction was not as significantly inhibited by cathepsin inhibitors as by antioxidants. Both NAC and α-toco protected against caspase-3 induction following PB282 treatment, while only NAC offered protection following SW43 treatment. The caspase-3 inhibitor DEVD-FMK offered significant protection from PB282, but not SW43. Sigma-2 ligand SW43 commits pancreatic cancer cells to death by a caspase-independent process involving LMP and oxidative stress which is protected from by NAC. PB282 however undergoes a caspase-dependent death following LMP protected by DEVD-FMK and α-toco, which is also known to stabilize the mitochondrial membrane during apoptotic stimuli. These differences in mechanism are likely dependent on the structural class of the compounds versus the inherent sigma-2 binding affinity. As resistance of pancreatic cancers to specific apoptotic stimuli from chemotherapy is better appreciated, and patient-tailored treatments become more available, ligands with high sigma-2 receptor affinity should be chosen based on sensitivities to apoptotic pathways.
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影响因子：
7.8
作者：
CHEN, JW;MURPHY, TL;WILLINGHAM, MC;PASTAN, I;AUGUST, JT
通讯作者：
AUGUST, JT
影响因子：
7.4
作者：
Kashiwagi H;McDunn JE;Simon PO Jr;Goedegebuure PS;Vangveravong S;Chang K;Hotchkiss RS;Mach RH;Hawkins WG
通讯作者：
Hawkins WG
影响因子：
4.8
作者：
Huss, M;Ingenhorst, G;Wieczorek, H
通讯作者：
Wieczorek, H
影响因子：
7.3
作者：
Berardi, F;Colabufo, NA;Lucchi, L
通讯作者：
Lucchi, L
影响因子：
37.3
作者：
Hornick, John R.;Xu, Jinbin;Hawkins, William G.
通讯作者：
Hawkins, William G.