Mashal R D, Lester S C, Sklar J
Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts.
Cancer Res. 1993 Oct 1;53(19):4676-9.
Analysis of clonality by X chromosome inactivation has proven to be a powerful strategy in the study of neoplastic and preneoplastic disorders (P. J. Fialkow, Biochim. Biophys. Acta, 458: 283-321, 1976; B. Vogelstein et al., Cancer Res., 47: 4806-4813, 1987). Recently, the gene for the androgen receptor has been shown to be a highly polymorphic locus in which methylation of DNA correlates with inactivation of one or the other X homologue (R. C. Allen et al., Am. J. Hum. Genet., 51: 1229-1239, 1992). Unlike other loci used for analysis of X inactivation, the methylation sites within the androgen receptor gene lie close to the region of DNA containing the polymorphism. Consequently, it should be possible to use methylation-sensitive restriction enzymes and polymerase chain reaction to study differential methylation among alleles of this gene in formalin-fixed and paraffin-embedded archival tissue specimens. To investigate this question, we performed clonal analysis on a variety of randomly selected, formalin-fixed, paraffin-embedded tumor tissues from 15 women. Thirteen of the women were found to be heterozygous for polymorphisms at the androgen receptor locus. Among these women, 11 tumors were clearly clonal in assays of methylation of the androgen receptor gene. Interpretation of results for the remaining two cases was complicated because of a skewed pattern of X chromosome inactivation found in normal control tissues. We conclude that analysis of methylation in the androgen receptor gene should allow study of clonality in most formalin-fixed, paraffin-embedded tissue specimens from women, including small preneoplastic lesions or rare conditions for which sufficient material is not available for analysis by other techniques.
通过X染色体失活分析克隆性已被证明是研究肿瘤性和肿瘤前疾病的一种强大策略（P. J. 菲亚尔科夫，《生物化学与生物物理学学报》，458: 283 - 321, 1976；B. 沃格尔斯坦等人，《癌症研究》，47: 4806 - 4813, 1987）。最近，雄激素受体基因已被证明是一个高度多态性位点，其中DNA甲基化与一条或另一条X同源染色体的失活相关（R. C. 艾伦等人，《美国人类遗传学杂志》，51: 1229 - 1239, 1992）。与用于分析X失活的其他位点不同，雄激素受体基因内的甲基化位点靠近包含多态性的DNA区域。因此，应该有可能使用甲基化敏感限制酶和聚合酶链反应来研究福尔马林固定和石蜡包埋存档组织标本中该基因等位基因之间的差异甲基化。为了研究这个问题，我们对15名女性的各种随机选择的福尔马林固定、石蜡包埋肿瘤组织进行了克隆分析。发现其中13名女性在雄激素受体位点的多态性方面是杂合的。在这些女性中，11个肿瘤在雄激素受体基因甲基化检测中明显是克隆性的。由于在正常对照组织中发现X染色体失活模式偏斜，其余两例结果的解释较为复杂。我们得出结论，雄激素受体基因甲基化分析应该能够研究大多数来自女性的福尔马林固定石蜡包埋组织标本中的克隆性，包括小的肿瘤前病变或因材料不足无法用其他技术分析的罕见情况。
