Vilner B J, John C S, Bowen W D
Unit on Receptor Biochemistry and Pharmacology, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Cancer Res. 1995 Jan 15;55(2):408-13.
Thirteen tumor-derived cell lines of human and nonhuman origin and from various tissues were examined for the presence and density of sigma-1 and sigma-2 receptors. Sigma-1 receptors of a crude membrane fraction were labeled using 3H-pentazocine, and sigma-2 receptors were labeled with [3H]1,3-di-o-tolylguanidine ([3H]DTG); in the presence or absence of dextrallorphan. 3H-Pentazocine-binding sites were heterogeneous. In rodent cell lines (e.g., C6 glioma, N1E-115 neuroblastoma, and NG108-15 neuroblastoma x glioma hybrid), human T47D breast ductal carcinoma, human NCI-H727 lung carcinoid, and human A375 melanoma, 3H-pentazocine bound to high- and low-affinity sites with Kd1 = 0.67-7.0 nM, Bmax1 = 25.5-108 fmol/mg protein, Kd2 = 127-600 nM, and Bmax2 = 942-5431 fmol/mg protein. However, 3H-pentazocine bound to a single site in other cell lines. In human U-138MG glioblastoma, SK-N-SH neuroblastoma, and LNCaP.FGC prostate, Kd = 28-61 nM and Bmax = 975-1196 fmol/mg protein, whereas in ThP-1 leukemia Kd = 146 nM and Bmax = 1411 fmol/mg protein. The sigma-1-like nature of 3H-pentazocine-binding sites was confirmed by competition studies which revealed high affinity for haloperidol and enantioselectivity for (+)-pentazocine over (-)-pentazocine. Interestingly, human MCF-7 breast adenocarcinoma showed little or no specific binding of 3H-pentazocine, suggesting the absence of sigma-1 receptors in this cell line. All cell lines examined expressed a high density of sigma-2 receptors with Kd values for [3H]DTG ranging from 20 to 101 nM and Bmax values of 491 to 7324 fmol/mg protein. Competition studies indicated possible heterogeneity of sigma-2 receptors. While sites labeled by [3H]DTG in all cell lines tested exhibited affinity for haloperidol and preference for (-)-pentazocine over the (+)-enantiomer, human cell lines generally showed 4- to 7-fold lower affinity for haloperidol and approximately 10-fold lower affinity for (-)-pentazocine compared with the rodent cell lines. The high density of sigma-1 and sigma 2-binding sites in these cell lines suggests important cellular functions in cancer, as well as potential diagnostic utility for tumor-imaging agents which target sigma sites. These cell lines may be useful as model systems in which to study the functions of sigma sites in normal tissues, as well as their possible role in tumor biology.
对13种来源于人类和非人类、来自不同组织的肿瘤衍生细胞系进行了σ-1和σ-2受体的存在情况及密度检测。使用3H-喷他佐辛标记粗膜组分的σ-1受体，并用[3H]1,3-二邻甲苯基胍（[3H]DTG）标记σ-2受体；在有或没有右美沙芬的情况下进行。3H-喷他佐辛结合位点具有异质性。在啮齿动物细胞系（如C6胶质瘤、N1E-115神经母细胞瘤和NG108-15神经母细胞瘤×胶质瘤杂交细胞系）、人T47D乳腺导管癌、人NCI-H727肺类癌和人A375黑色素瘤中，3H-喷他佐辛与高亲和力和低亲和力位点结合，Kd1 = 0.67 - 7.0 nM，Bmax1 = 25.5 - 108 fmol/mg蛋白，Kd2 = 127 - 600 nM，Bmax2 = 942 - 5431 fmol/mg蛋白。然而，3H-喷他佐辛在其他细胞系中与单个位点结合。在人U-138MG胶质母细胞瘤、SK-N-SH神经母细胞瘤和LNCaP.FGC前列腺癌中，Kd = 28 - 61 nM，Bmax = 975 - 1196 fmol/mg蛋白，而在ThP-1白血病中，Kd = 146 nM，Bmax = 1411 fmol/mg蛋白。3H-喷他佐辛结合位点的σ-1样性质通过竞争研究得到证实，该研究显示其对氟哌啶醇具有高亲和力，对(+)-喷他佐辛比对(-)-喷他佐辛具有对映体选择性。有趣的是，人MCF-7乳腺腺癌显示3H-喷他佐辛几乎没有或没有特异性结合，表明该细胞系中不存在σ-1受体。所有检测的细胞系都表达高密度的σ-2受体，[3H]DTG的Kd值范围为20至101 nM，Bmax值为491至7324 fmol/mg蛋白。竞争研究表明σ-2受体可能具有异质性。虽然在所有测试的细胞系中由[3H]DTG标记的位点对氟哌啶醇具有亲和力，并且对(-)-喷他佐辛比对(+)-对映体更偏好，但与人细胞系相比，啮齿动物细胞系对氟哌啶醇的亲和力通常低4至7倍，对(-)-喷他佐辛的亲和力低约10倍。这些细胞系中σ-1和σ-2结合位点的高密度表明其在癌症中具有重要的细胞功能，以及对靶向σ位点的肿瘤成像剂具有潜在的诊断用途。这些细胞系可用作模型系统，用于研究σ位点在正常组织中的功能及其在肿瘤生物学中的可能作用。
