Department of Obstetrics and Gynecology, University Medical Center Regensburg, Landshuter Str. 65, 93053, Regensburg, Germany.
Second Department of Gynecology, Medical University of Lublin, Lublin, Poland.
BMC Cancer. 2019 Jul 29;19(1):745. doi: 10.1186/s12885-019-5928-2.
Estrogen receptor β (ERβ) has been repeatedly suggested to play important roles in hormone-dependent cancer like in tumors of the breast, ovary or prostate. In this study, we intended to further elucidate its role in endometrial cancer.
For this purpose, we knocked down ERβ expression in two endometrial cancer cell lines, the ERα-negative/ERβ-positive line HEC-1A and the ERα/β-positive cell line RL95/2, by means of siRNA transfection. Cell proliferation after transfection was assessed using the fluorescent CTB Assay (Promega). In order to elucidate possible molecular mechanisms which might underlie the effect on proliferation, we performed transcriptome analyses by means of human Affymetrix Human Gene Chip 2.0. Additionally, we treated the employed cell lines with different ERβ modulators to examine their effect on proliferation.
siRNA-mediated knockdown of ERβ significantly increased proliferation of both endometrial cancer cell lines. In HEC-1A cells, proliferation was significantly increased 4, 5 and 6 days after transfection, with a maximum of about 1.7-fold (p < 0.05) on day 6. Endometrial RL95/2 cells with an ERβ knockdown exhibited a clearly enhanced proliferation on day 3 and days 4 to 8, when even 2.4-fold higher numbers of viable cells were detected (p < 0.01). Transcriptome analysis revealed that this was accompanied by increased expression of several genes being known to be upregulated in cancer, including proliferation-associated genes and oncogenes, and by repression of genes associated with differentiation, apoptosis or growth inhibition. Corroborating the observed knockdown effects, treatment with the ERβ antagonists PHTTP and (R, R) THC was also able to induce proliferation of both cell lines.
Our data clearly support the putative role of ERβ as tumor suppressor in endometrium as previously suggested in studies on other tissues and encourage further studies to find out to what extent this molecule might be a potential therapy target in this cancer entity.
雌激素受体 β（ERβ）已被反复证明在激素依赖性癌症中发挥重要作用，如乳腺癌、卵巢癌或前列腺癌。在这项研究中，我们旨在进一步阐明其在子宫内膜癌中的作用。
为此，我们通过 siRNA 转染敲低了两种子宫内膜癌细胞系，即 ERα-阴性/ERβ-阳性的 HEC-1A 系和 ERα/β-阳性的 RL95/2 系中的 ERβ 表达。转染后通过荧光 CTB 分析（Promega）评估细胞增殖。为了阐明可能是增殖效应基础的潜在分子机制，我们通过人类 Affymetrix Human Gene Chip 2.0 进行了转录组分析。此外，我们用不同的 ERβ调节剂处理所使用的细胞系，以检查它们对增殖的影响。
siRNA 介导的 ERβ 敲低显著增加了两种子宫内膜癌细胞系的增殖。在 HEC-1A 细胞中，转染后 4、5 和 6 天，增殖明显增加，第 6 天达到约 1.7 倍（p<0.05）。具有 ERβ 敲低的子宫内膜 RL95/2 细胞在第 3 天和第 4 天至第 8 天表现出明显增强的增殖，此时检测到的活细胞数甚至增加了 2.4 倍（p<0.01）。转录组分析显示，这伴随着一些已知在癌症中上调的基因的表达增加，包括增殖相关基因和癌基因，以及与分化、凋亡或生长抑制相关的基因的抑制。与观察到的敲低效应一致，用 ERβ 拮抗剂 PHTTP 和（R，R）THC 处理也能诱导两种细胞系的增殖。
我们的数据清楚地支持 ERβ 作为子宫内膜肿瘤抑制因子的假定作用，如先前在其他组织的研究中所表明的，并鼓励进一步的研究，以了解该分子在这种癌症实体中作为潜在治疗靶点的程度。
