Bunn P A, Chan D, Stewart J, Gera L, Tolley R, Jewett P, Tagawa M, Alford C, Mochzuki T, Yanaihara N
Department of Medicine, University of Colorado Cancer Center, Denver 80262.
Cancer Res. 1994 Jul 1;54(13):3602-10.
Small cell lung cancers (SCLC) and some non-small cell lung cancers (NSCLC) have neuroendocrine features which include production of a variety of neuropeptides, cell surface expression of the receptors for these peptides, and autocrine stimulation by the peptides. Previous studies showed that some peptide antagonists and anti-peptide antibodies inhibited the growth of SCLC cell lines which expressed receptors for the specific peptide. We and others showed that the heterogeneity of peptide receptor expression and responsiveness was a major potential obstacle for developing therapeutic uses of peptide antagonists. In this manuscript we evaluated the effects of 11 peptide antagonists (3 bombesin-specific, 2 cholecystokinin-specific, 1 arginine vasopressin (AVP)-specific, and 5 substance P derivatives with broad specificity) on peptide-induced calcium mobilization and growth of SCLC and NSCLC cell lines. For each antagonist, we determined the dose-response effects, specificity of peptide antagonism, and biological stability in serum using Indo-1AM-based flow cytometric assays. We found that the three bombesin antagonists, S30, SC196, and L336,175, varied in potency from 10 nM to 10 microM, varied in serum stability from 6 h to more than 24 h, and had no effect on the calcium response elicited by other peptides. None of these compounds effectively inhibited the growth of SCLC cell lines in [3H]dThd and cell growth assays in vitro. Similarly, the three cholecystokinin and AVP antagonists were highly specific for cholecystokinin and AVP, respectively, had widely varying potency, but had little inhibitory effect on SCLC growth in vitro. In contrast, the five substance P derivatives inhibited the calcium response to bombesin, AVP, bradykinin, and fetal bovine serum. None of these five antagonists were as potent as the six specific antagonists described above, but they were more effective in inhibiting the growth of SCLC cell lines in vitro. These substance P derivatives inhibited the growth of peptide-sensitive SCLC cell lines more efficiently than their inhibition of peptide-insensitive NSCLC or breast cancer cell lines. Relatively high concentrations of these substance P derivatives were required to inhibit in vitro growth, even in the absence of added peptide. It is likely that more potent broad spectrum antagonists, toxins, or radiolabeled stable antagonists will need to be developed for maximal clinical development of this type of anti-growth factor therapy.
小细胞肺癌（SCLC）和一些非小细胞肺癌（NSCLC）具有神经内分泌特征，包括产生多种神经肽、这些肽的受体在细胞表面的表达以及肽的自分泌刺激。先前的研究表明，一些肽拮抗剂和抗肽抗体可抑制表达特定肽受体的SCLC细胞系的生长。我们和其他人表明，肽受体表达和反应性的异质性是开发肽拮抗剂治疗用途的主要潜在障碍。在本论文中，我们评估了11种肽拮抗剂（3种蛙皮素特异性、2种胆囊收缩素特异性、1种精氨酸加压素（AVP）特异性和5种具有广泛特异性的P物质衍生物）对肽诱导的SCLC和NSCLC细胞系钙动员和生长的影响。对于每种拮抗剂，我们使用基于Indo-1AM的流式细胞术测定法确定了剂量反应效应、肽拮抗的特异性以及在血清中的生物稳定性。我们发现，三种蛙皮素拮抗剂S30、SC196和L336,175，效力在10 nM至10 microM之间变化，血清稳定性在6小时至超过24小时之间变化，并且对其他肽引发的钙反应没有影响。在[3H]dThd和体外细胞生长测定中，这些化合物均未有效抑制SCLC细胞系的生长。同样，三种胆囊收缩素和AVP拮抗剂分别对胆囊收缩素和AVP具有高度特异性，效力差异很大，但对体外SCLC生长几乎没有抑制作用。相比之下，五种P物质衍生物抑制了对蛙皮素、AVP、缓激肽和胎牛血清的钙反应。这五种拮抗剂均不如上述六种特异性拮抗剂有效，但它们在体外抑制SCLC细胞系生长方面更有效。这些P物质衍生物抑制肽敏感的SCLC细胞系生长的效率高于其抑制肽不敏感的NSCLC或乳腺癌细胞系的效率。即使在没有添加肽的情况下，也需要相对高浓度的这些P物质衍生物来抑制体外生长。为了这种抗生长因子疗法的最大临床开发，可能需要开发更有效的广谱拮抗剂、毒素或放射性标记的稳定拮抗剂。
