Emons G, Ortmann O, Becker M, Irmer G, Springer B, Laun R, Hölzel F, Schulz K D, Schally A V
Department of Obstetrics and Gynecology, Philipps University, Marburg, Germany.
Cancer Res. 1993 Nov 15;53(22):5439-46.
Recently, specific binding sites for luteinizing hormone releasing hormone (LHRH) and its analogues have been demonstrated in biopsy samples of human epithelial ovarian cancer. Their biological significance remained obscure. In this study we ascertained whether such LHRH-binding sites are also present in the human epithelial ovarian cancer cell lines EFO-21 and EFO-27 and if they could mediate antiproliferative effects of LHRH analogues. Using [125I, D-Trp6]LHRH, a high affinity/low capacity binding site was detected in both lines: EFO-21 (Kd1 = 1.5 x 10(-9) M; binding capacity (Bmax1) = 4.9 fmol/10(6) cells) and EFO-27 (Kd1 = 1.7 x 10(-9) M; Bmax1 = 3 fmol/10(6) cells). In addition, a second class of low affinity/high capacity binding sites (EFO-21: Kd2 = 7.5 x 10(-6) M; Bmax2 = 24 pmol/10(6) cells; EFO-27: Kd2 = 4.3 x 10(-6) M; Bmax2 = 14.5 pmol/10(6) cells) was demonstrated. Specific binding of [125I, D-Trp6]LHRH was displaced with nearly equal efficiency by unlabeled [D-Trp6]LHRH, the LHRH-antagonists SB-75 and Hoe-013, and by native LHRH but not by unrelated peptides such as oxytocin and somatostatin. In the presence of 10(-5) M agonist [D-Trp6]LHRH, the proliferation of both cell lines was significantly reduced to 77% of controls after 24 h and to approx. 60% after 6 days. Lower concentrations (10(-9) M) of the agonist, significantly decreased the proliferation to 87.5% for EFO-21 and 86% for EFO-27 after 6 days. These antiproliferative effects were enhanced by increasing doses of [D-Trp6]LHRH and were maximal at 10(-5) M (EFO-21: 65.5% of control, EFO-27: 68% of control). Similar dose-dependent antiproliferative effects were obtained in EFO-21 line with the LHRH-antagonists SB-75 and Hoe-013, while these analogues had no effects on the proliferation of EFO-27 cells. SB-75 partly antagonized the antiproliferative effect of [D-Trp6]LHRH in a dose dependent way in the EFO-27 line. These data suggest that LHRH analogues can directly inhibit the in vitro proliferation of human ovarian cancer cells. This effect might be mediated through the high affinity LHRH binding sites.
最近，在人上皮性卵巢癌活检样本中已证实存在促黄体生成素释放激素（LHRH）及其类似物的特异性结合位点。但其生物学意义仍不清楚。在本研究中，我们确定人上皮性卵巢癌细胞系EFO - 21和EFO - 27中是否也存在此类LHRH结合位点，以及它们是否能介导LHRH类似物的抗增殖作用。使用[125I, D - Trp6]LHRH，在这两种细胞系中均检测到一个高亲和力/低容量结合位点：EFO - 21（解离常数Kd1 = 1.5×10(-9) M；结合容量Bmax1 = 4.9 fmol/10(6)个细胞）和EFO - 27（Kd1 = 1.7×10(-9) M；Bmax1 = 3 fmol/10(6)个细胞）。此外，还证实存在第二类低亲和力/高容量结合位点（EFO - 21：Kd2 = 7.5×10(-6) M；Bmax2 = 24 pmol/10(6)个细胞；EFO - 27：Kd2 = 4.3×10(-6) M；Bmax2 = 14.5 pmol/10(6)个细胞）。未标记的[D - Trp6]LHRH、LHRH拮抗剂SB - 75和Hoe - 013以及天然LHRH能以几乎相同的效率取代[125I, D - Trp6]LHRH的特异性结合，而无关肽如催产素和生长抑素则不能。在10(-5) M激动剂[D - Trp6]LHRH存在的情况下，两种细胞系的增殖在24小时后均显著降低至对照的77%，6天后降至约60%。较低浓度（10(-9) M）的激动剂在6天后使EFO - 21的增殖显著降低至87.5%，使EFO - 27的增殖降低至86%。这些抗增殖作用通过增加[D - Trp6]LHRH的剂量而增强，在10(-5) M时达到最大（EFO - 21：对照的65.5%，EFO - 27：对照的68%）。在EFO - 21细胞系中，LHRH拮抗剂SB - 75和Hoe - 013也获得了类似的剂量依赖性抗增殖作用，而这些类似物对EFO - 27细胞的增殖没有影响。在EFO - 27细胞系中，SB - 75以剂量依赖性方式部分拮抗了[D - Trp6]LHRH的抗增殖作用。这些数据表明，LHRH类似物可直接抑制人卵巢癌细胞的体外增殖。这种作用可能是通过高亲和力LHRH结合位点介导的。
