Heikkila R, Trepel J B, Cuttitta F, Neckers L M, Sausville E A
Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland 20892.
J Biol Chem. 1987 Dec 5;262(34):16456-60.
To examine the biochemical basis for growth factor-induced responses in human lung cancer cells, we used the quin2 technique to study the effect of the amphibian peptide bombesin and its congeners including mammalian gastrin-releasing peptide (GRP) on the intracellular free calcium level [Ca2+]i in small cell lung cancer cell lines. In five of eleven cell lines tested, Tyr4-bombesin or GRP elicited a rapid and transient increase in [Ca2+]i. The response was seen with as little as 1 nM ligand, was not affected by membrane depolarization, and derived in part from internal calcium stores. Desensitization to a second addition of active bombesin congeners occurs subsequent to initial addition of Tyr4-bombesin. Structure-activity analysis showed the carboxyl-terminal octapeptide was the active portion of the peptide. Analogs in which the carboxyl terminus was oxidized or deamidated were inactive. Ranatensin, litorin, alytesin, and GRP, but not physalaemin, were as active as Tyr4-bombesin. A monoclonal antibody to the carboxyl terminus of bombesin selectively blocked the increased [Ca2+]i elicited by Tyr4-bombesin. These studies suggest that bombesin congeners can act on some small cell lung cancer cell lines by a pathway utilizing increased [Ca2+]i.
为了研究人类肺癌细胞中生长因子诱导反应的生化基础，我们使用喹啉-2技术来研究两栖类肽蛙皮素及其同类物（包括哺乳动物胃泌素释放肽，GRP）对小细胞肺癌细胞系细胞内游离钙水平[Ca2+]i的影响。在测试的11个细胞系中的5个中，Tyr4-蛙皮素或GRP引起了[Ca2+]i的快速短暂升高。这种反应在低至1 nM的配体浓度下即可观察到，不受膜去极化的影响，部分来源于细胞内钙库。在首次添加Tyr4-蛙皮素后，对再次添加的活性蛙皮素同类物会产生脱敏现象。结构-活性分析表明，羧基末端八肽是该肽的活性部分。羧基末端被氧化或脱酰胺的类似物无活性。蛙皮缩胆囊素、雨蛙肽、产婆蟾肽和GRP（但不是铃蟾肽）与Tyr4-蛙皮素活性相同。一种针对蛙皮素羧基末端的单克隆抗体选择性地阻断了Tyr4-蛙皮素引起的[Ca2+]i升高。这些研究表明，蛙皮素同类物可通过利用[Ca2+]i升高的途径作用于某些小细胞肺癌细胞系。
