D.O. Ott Research Institute of Obstetrics, Gynecology and Reproductology, St. Petersburg, Russian Federation,
Department of Genetics and Biotechnology, Saint Petersburg State University, St. Petersburg, Russian Federation,
Cytogenet Genome Res. 2021;161(1-2):43-51. doi: 10.1159/000513173. Epub 2021 Feb 5.
In the present study, we aimed to check whether uterine leiomyomas (ULs) with an apparently normal karyotype in vitro comprise "hidden" cell subpopulations with numerical chromosome abnormalities (heteroploid cells). A total of 32 ULs obtained from 32 patients were analyzed in the study. Each UL was sampled for in vivo and in vitro cytogenetic studies. Karyotyping was performed on metaphase preparations from the cultured UL samples. A normal karyotype was revealed in 20 out of the 32 ULs, of which 9 were selected for further study based on the good quality of the interphase preparations. Then, using interphase FISH with centromeric DNA probes, we analyzed the copy number of chromosomes 7 and 16 in 1,000 uncultured and 1,000 cultured cells of each selected UL. All of the ULs included both disomic cells representing a predominant subpopulation and heteroploid cells reaching a maximum frequency of 21.6% (mean 9.8%) in vivo and 11.5% (mean 6.1%) in vitro. The spectrum of heteroploid cells was similar in vivo and in vitro and mostly consisted of monosomic and tetrasomic cells. However, their frequencies in the cultured samples differed from those in the uncultured ones: while the monosomic cells decreased in number, the tetrasomic cells became more numerous. The frequency of either monosomic or tetrasomic cells both in vivo and in vitro was not associated with the presence of MED12 exon 2 mutations in the tumors. Our results suggest that ULs with an apparently normal karyotype consist of both karyotypically normal and heteroploid cells, implying that the occurrence of minor cell subpopulations with numerical chromosome abnormalities may be considered a characteristic of UL tumorigenesis. Different frequencies of heteroploid cells in vivo and in vitro suggest their dependence on microenvironmental conditions, thus providing a pathway for regulation of their propagation, which may be important for the UL pathogenesis.
在本研究中，我们旨在检查体外具有正常核型的子宫平滑肌瘤（ULs）是否包含具有染色体数目异常（异倍体细胞）的“隐藏”细胞亚群。研究共分析了 32 名患者的 32 个 UL。对每个 UL 进行了体内和体外细胞遗传学研究。对培养的 UL 样本的中期制备物进行了核型分析。在 32 个 UL 中，有 20 个显示正常核型，其中 9 个根据间期制备物的良好质量被选择用于进一步研究。然后，使用间期 FISH 与着丝粒 DNA 探针，我们分析了每个选定 UL 的 1000 个未培养和 1000 个培养细胞中染色体 7 和 16 的拷贝数。所有 UL 均包含占主导地位亚群的二倍体细胞和异倍体细胞，体内最大频率为 21.6%（平均值为 9.8%），体外最大频率为 11.5%（平均值为 6.1%）。体内和体外的异倍体细胞谱相似，主要由单体和四倍体细胞组成。然而，它们在培养样本中的频率与未培养样本中的频率不同：单体细胞数量减少，四倍体细胞数量增加。无论是在体内还是体外，单体或四倍体细胞的频率都与肿瘤中 MED12 外显子 2 突变的存在无关。我们的结果表明，具有正常核型的 UL 由核型正常和异倍体细胞组成，这表明存在具有染色体数目异常的少数细胞亚群可能被认为是 UL 肿瘤发生的特征。体内和体外异倍体细胞的不同频率表明它们依赖于微环境条件，从而为调节其增殖提供了途径，这对 UL 发病机制可能很重要。
