Sigma-2 receptor agonists activate a novel apoptotic pathway and potentiate antineoplastic drugs in breast tumor cell lines.
Sigma-2 receptor agonists activate a novel apoptotic pathway and potentiate antineoplastic drugs in breast tumor cell lines.
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发表时间：
2002
期刊：
影响因子：
11.2
通讯作者：
K. Crawford;W. Bowen
中科院分区：
文献类型：
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作者：
K. Crawford;W. Bowen
我们之前报道过sigma-2受体在多种肿瘤细胞类型中高密度表达（B. J. Vilner et al., Cancer Res., 55: 408-413, 1995），并且各种sigma配体具有细胞毒性作用（B. J. Vilner et al.， J. Neurosci.）。科学进展，15:117-134,1995)。其他研究者已经证实在快速增殖的肿瘤中sigma-2受体的表达增加（R. H. Mach等，Cancer Res., 57: 156- 161,1997）和一些sigma配体抑制增殖的能力（P. J. Brent和G. T. Pang, Eur.）。j .杂志。中华医学杂志，1995)。我们在这里证明了sigma-2受体激动剂通过与细胞凋亡一致的机制诱导细胞死亡的能力。在对抗肿瘤药物敏感（MCF-7）和耐药（MCF-7/Adr-、T47D和SKBr3）的乳腺肿瘤细胞系中，与sigma-2亚型选择性激动剂CB-64D和CB-184孵育产生剂量依赖性的细胞毒性（通过乳酸脱氢酶释放到培养基中来测量）。无论p53基因型和耐药表型如何，这种反应的EC（50）在不同细胞系中是相似的。CB-64D和亚型非选择性sigma-2激动剂氟哌啶醇和还原氟哌啶醇在MCF-7和T47D细胞中诱导末端脱氧核苷酸转移酶介导的dUTP缺口末端标记染色，表明细胞通过凋亡发生死亡。CB-64D引起的Annexin V结合增加也表明细胞凋亡。在MCF-7细胞中，抗肿瘤药物阿霉素和放线菌素D诱导的细胞毒性和膜联蛋白V结合被某些特定的和一般的半胱天冬酶抑制剂部分或完全消除。相反，caspase抑制剂对sigma-2受体介导的（CB-64D和CB-184）细胞毒性或膜联蛋白V结合没有影响。在药物敏感（MCF-7）和耐药（MCF-7/Adr-）细胞系中，亚毒性剂量的CB-184与阿霉素或放线菌素D联合使用可显著增强细胞毒性。氟哌啶醇仅在耐药细胞中增强阿霉素。这些发现表明，sigma-2受体使用了一种新的p53和caspase不依赖的凋亡途径，这与一些dna损伤、抗肿瘤药物和其他凋亡刺激所使用的机制不同。这些观察结果进一步表明，sigma-2受体可能是治疗药物敏感和耐药转移性肿瘤的靶点。
We have reported previously that sigma-2 receptors are expressed in high densities in a variety of tumor cell types (B. J. Vilner et al., Cancer Res., 55: 408-413, 1995) and that various sigma ligands have cytotoxic effects (B. J. Vilner et al., J. Neurosci., 15: 117-134, 1995). Other investigators have demonstrated increased expression of sigma-2 receptors in rapidly proliferating tumors (R. H. Mach et al., Cancer Res., 57: 156-161, 1997) and the ability of some sigma ligands to inhibit proliferation (P. J. Brent and G. T. Pang, Eur. J. Pharmacol., 278: 151-160, 1995). We demonstrate here the ability of sigma-2 receptor agonists to induce cell death by a mechanism consistent with apoptosis. In breast tumor cell lines that are sensitive (MCF-7) and resistant (MCF-7/Adr-, T47D, and SKBr3) to antineoplastic agents, incubation with the sigma-2 subtype-selective agonists CB-64D and CB-184 produced dose-dependent cytotoxicity (measured by lactate dehydrogenase release into medium). The EC(50) for this response was similar across cell lines, irrespective of p53 genotype and drug-resistance phenotype. CB-64D and the subtype nonselective sigma-2 agonists haloperidol and reduced haloperidol induced terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining in MCF-7 and T47D cells, indicating that cell death occurs via apoptosis. Apoptosis was also indicated by increases in Annexin V binding caused by CB-64D. In MCF-7 cells, cytotoxicity and Annexin V binding induced by the antineoplastics doxorubicin and actinomycin D was partially or completely abrogated by certain specific and general inhibitors of caspases. In contrast, caspase inhibitors had no effect on sigma-2 receptor-mediated (CB-64D and CB-184) cytotoxicity or Annexin V binding. Marked potentiation of cytotoxicity was observed when a subtoxic dose of CB-184 was combined with doxorubicin or actinomycin D, both in drug-sensitive (MCF-7) and drug-resistant (MCF-7/Adr-) cell lines. Haloperidol potentiated doxorubicin only in drug-resistant cells. These findings suggest the involvement of a novel p53- and caspase-independent apoptotic pathway used by sigma-2 receptors, which is distinct from mechanisms used by some DNA-damaging, antineoplastic agents and other apoptotic stimuli. These observations further suggest that sigma-2 receptors may be targets that can be therapeutically exploited in the treatment of both drug-sensitive and drug-resistant metastatic tumors.