Mitchell Rod T, Camacho-Moll Maria, Macdonald Joni, Anderson Richard A, Kelnar Christopher Jh, O'Donnell Marie, Sharpe Richard M, Smith Lee B, Grigor Ken M, Wallace W Hamish B, Stoop Hans, Wolffenbuttel Katja P, Donat Roland, Saunders Philippa Tk, Looijenga Leendert Hj
MRC Centre for Reproductive Health, The University of Edinburgh, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh, EH16 4TJ, Scotland, UK.
Edinburgh Royal Hospital for Sick Children, 9 Sciennes Road, Edinburgh, EH9 1LF, Scotland, UK.
Mod Pathol. 2014 Sep;27(9):1255-1266. doi: 10.1038/modpathol.2013.246. Epub 2014 Jan 24.
Testicular germ cell cancer develops from premalignant intratubular germ cell neoplasia, unclassified cells that are believed to arise from failure of normal maturation of fetal germ cells from gonocytes (OCT4(+)/MAGEA4(-)) into pre-spermatogonia (OCT4(-)/MAGEA4(+)). Intratubular germ cell neoplasia cell subpopulations based on stage of germ cell differentiation have been described, however the importance of these subpopulations in terms of invasive potential has not been reported. We hypothesized that cells expressing an immature (OCT4(+)/MAGEA4(-)) germ cell profile would exhibit an increased proliferation rate compared with those with a mature profile (OCT4(+)/MAGEA4(+)). Therefore, we performed triple immunofluorescence and stereology to quantify the different intratubular germ cell neoplasia cell subpopulations, based on expression of germ cell (OCT4, PLAP, AP2γ, MAGEA4, VASA) and proliferation (Ki67) markers, in testis sections from patients with preinvasive disease, seminoma, and non-seminoma. We compared these subpopulations with normal human fetal testis and with seminoma cells. Heterogeneity of protein expression was demonstrated in intratubular germ cell neoplasia cells with respect to gonocyte and spermatogonial markers. It included an embryonic/fetal germ cell subpopulation lacking expression of the definitive intratubular germ cell neoplasia marker OCT4, that did not correspond to a physiological (fetal) germ cell subpopulation. OCT4(+)/MAGEA4(-) cells showed a significantly increased rate of proliferation compared with the OCT4(+)/MAGEA4(+) population (12.8 versus 3.4%, P<0.0001) irrespective of histological tumor type, reflected in the predominance of OCT4(+)/MAGEA4(-) cells in the invasive tumor component. Surprisingly, OCT4(+)/MAGEA4(-) cells in patients with preinvasive disease showed significantly higher proliferation compared to those with seminoma or non-seminoma (18.1 versus 10.2 versus 7.2%, P<0.05, respectively). In conclusion, this study has demonstrated that OCT4(+)/MAGEA4(-) cells are the most frequent and most proliferative cell population in tubules containing intratubular germ cell neoplasia, which appears to be an important factor in determining invasive potential of intratubular germ cell neoplasia to seminomas.
睾丸生殖细胞癌由癌前性管内生殖细胞瘤变发展而来，这种未分类的细胞被认为是由于胎儿生殖细胞从生殖母细胞（OCT4(+)/MAGEA4(-)）正常成熟为精原细胞前体细胞（OCT4(-)/MAGEA4(+)）失败所致。基于生殖细胞分化阶段的管内生殖细胞瘤变细胞亚群已被描述，然而这些亚群在侵袭潜能方面的重要性尚未见报道。我们推测，与具有成熟特征（OCT4(+)/MAGEA4(+)）的细胞相比，表达不成熟（OCT4(+)/MAGEA4(-)）生殖细胞特征的细胞增殖率会增加。因此，我们进行了三重免疫荧光和体视学分析，以定量基于生殖细胞（OCT4、PLAP、AP2γ、MAGEA4、VASA）和增殖（Ki67）标志物表达的不同管内生殖细胞瘤变细胞亚群，这些样本来自原位癌、精原细胞瘤和非精原细胞瘤患者的睾丸切片。我们将这些亚群与正常人类胎儿睾丸以及精原细胞瘤细胞进行了比较。在管内生殖细胞瘤变细胞中，关于生殖母细胞和精原细胞标志物的蛋白质表达存在异质性。其中包括一个缺乏确定性管内生殖细胞瘤变标志物OCT4表达的胚胎/胎儿生殖细胞亚群，它并不对应于一个生理性（胎儿）生殖细胞亚群。无论组织学肿瘤类型如何，OCT4(+)/MAGEA4(-)细胞的增殖率均显著高于OCT4(+)/MAGEA4(+)群体（分别为12.8%和3.4%，P<0.0001），这反映在侵袭性肿瘤成分中OCT4(+)/MAGEA4(-)细胞占优势。令人惊讶的是，原位癌患者的OCT4(+)/MAGEA4(-)细胞增殖率显著高于精原细胞瘤或非精原细胞瘤患者（分别为18.1%、10.2%和7.2%，P<0.05）。总之，本研究表明，OCT4(+)/MAGEA4(-)细胞是含有管内生殖细胞瘤变的小管中最常见且增殖性最强的细胞群体，这似乎是决定管内生殖细胞瘤变向精原细胞瘤侵袭潜能的一个重要因素。
