Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy.
Cell Death Dis. 2013 Aug 1;4(8):e747. doi: 10.1038/cddis.2013.275.
We have previously shown that estrogens binding to estrogen receptor (ER) α increase proliferation of Leydig tumor cells. Estrogens can also bind to G protein-coupled ER (GPER) and activation of this receptor can either increase or decrease cell proliferation of several tumor types. The aim of this study was to investigate GPER expression in R2C rat tumor Leydig cells, evaluate effects of its activation on Leydig tumor cell proliferation and define the molecular mechanisms triggered in response to its activation. R2C cells express GPER and its activation, using the specific ligand G-1, is associated with decreased cell proliferation and initiation of apoptosis. Apoptosis after G-1 treatment was asserted by appearance of DNA condensation and fragmentation, decrease in Bcl-2 and increase in Bax expression, cytochrome c release, caspase and poly (ADP-ribose) polymerase-1 (PARP-1) activation. These effects were dependent on GPER activation because after silencing of the gene, using a specific small interfering RNA, cyt c release, PARP-1 activation and decrease in cell proliferation were abrogated. These events required a rapid, however, sustained extracellular regulated kinase 1/2 activation. G-1 was able to decrease the growth of R2C xenograft tumors in CD1 nude mice while increasing the number of apoptotic cells. In addition, in vivo administration of G-1 to male CD1 mice did not cause any alteration in testicular morphology, while cisplatin, the cytotoxic drug currently used for the therapy of Leydig tumors, severely damaged testicular structure, an event associated with infertility in cisplatin-treated patients. These observations indicate that GPER targeting for the therapy of Leydig cell tumor may represent a good alternative to cisplatin to preserve fertility in Leydig tumor patients.
我们之前已经表明，雌激素与雌激素受体（ER）α结合会增加莱迪希细胞瘤细胞的增殖。雌激素也可以与 G 蛋白偶联受体（GPER）结合，这种受体的激活可以增加或减少几种肿瘤类型的细胞增殖。本研究的目的是研究 R2C 大鼠肿瘤莱迪希细胞瘤中 GPER 的表达，评估其激活对莱迪希细胞瘤增殖的影响，并确定其激活所引发的分子机制。R2C 细胞表达 GPER，其激活（使用特定配体 G-1）与细胞增殖减少和凋亡起始有关。G-1 处理后的细胞凋亡通过 DNA 凝聚和片段化的出现、Bcl-2 减少和 Bax 表达增加、细胞色素 c 释放、半胱天冬酶和多聚（ADP-核糖）聚合酶-1（PARP-1）激活来证明。这些效应依赖于 GPER 的激活，因为在用特定的小干扰 RNA 沉默基因后，细胞色素 c 释放、PARP-1 激活和细胞增殖减少被阻断。这些事件需要快速但持续的细胞外调节激酶 1/2 激活。G-1 能够减少 CD1 裸鼠中 R2C 异种移植肿瘤的生长，同时增加凋亡细胞的数量。此外，在体内给予 G-1 不会引起雄性 CD1 小鼠睾丸形态发生任何改变，而顺铂，目前用于莱迪希细胞瘤治疗的细胞毒性药物，严重损害了睾丸结构，这与顺铂治疗患者的不育有关。这些观察结果表明，针对莱迪希细胞瘤的 GPER 靶向治疗可能是保留莱迪希细胞瘤患者生育能力的顺铂的良好替代方法。
