Choi Jung-Hye, Choi Kyung-Chul, Auersperg Nelly, Leung Peter C K
Department of Obstetrics and Gynecology, British Columbia Children's and Women's Hospital, British Columbia Research Institute for Children's and Women's Health, University of British Columbia, Vancouver, British Columbia, Canada V6H 3V5.
Endocr Relat Cancer. 2005 Jun;12(2):407-21. doi: 10.1677/erc.1.00896.
Gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) have been implicated as probable risk factors in epithelial ovarian carcinomas, most of which are derived from ovarian surface epithelium (OSE). Since epidermal growth factor (EGF) increases the growth of ovarian surface epithelial cells, we determined the effect of gonadotropins on the expression of epidermal growth factor receptor (EGFR). We investigated the basal levels of EGFR mRNA and protein, and the mechanisms involved in the regulation of EGFR at the transcriptional and translational levels by FSH and LH. The immortalized OSE cell lines (IOSE) derived from normal OSE cells by transfecting SV40 T-antigen (IOSE-80 and IOSE-80PC, a post-crisis line) and ovarian cancer cell lines were employed. A significantly lower level of EGFR was observed in both IOSE-80 and IOSE-80PC cells when compared with the ovarian cancer cell lines, OVCAR-3 and SKOV-3. Treatment of IOSE-80PC cells with FSH and LH (10(-7) and 10(-6) g/ml) resulted in a significant increase in EGFR mRNA at 24 h and EGFR protein at 48 h, whereas the treatment with gonadotropins for 24-48 h induced a mild increase in EGFR in OVCAR-3, but not in SKOV-3 cells. In addition, IOSE-80PC cells treated with gonadotropins and EGF (10 nM) exhibited an additive stimulation of mitogenesis. Further, FSH and LH significantly increased activities of various kinases at 5-10 min, and pre-treatments with LY294002 (an inhibitor of PI3K) or PD98059 (an inhibitor of ERK1/2) partially blocked the gonadotropin-induced up-regulation of EGFR in IOSE-80PC cells. We investigated whether the effect of gonadotropins on EGFR mRNA levels is induced by increased transcription and/or by altered mRNA stability. Treatment of IOSE-80PC cells with FSH (10(-7) and 10(-6) g/ml) significantly enhanced the activity of the EGFR promoter (120 and 140% increase, respectively) at 24 h, and treatment with LH (10(-7) g/ml) for 24 h induced an increase in the activity of EGFR promoter (30%) in these cells. On the other hand, LH resulted in a significant increase in EGFR mRNA stability in the decay curves. Taken together, these results suggest that the effect of gonadotropins on the expression of EGFR may affect cell growth via ERK-1/-2 and PI3K pathways in pre-neoplastic ovarian surface epithelial cells, and that FSH and LH increase EGFR mRNA by different mechanisms. The former increased EGFR gene transcription essentially, whereas the latter mainly enhanced EGFR mRNA stability.
促性腺激素，即卵泡刺激素（FSH）和黄体生成素（LH），被认为可能是上皮性卵巢癌的风险因素，其中大多数上皮性卵巢癌起源于卵巢表面上皮（OSE）。由于表皮生长因子（EGF）可促进卵巢表面上皮细胞的生长，我们研究了促性腺激素对表皮生长因子受体（EGFR）表达的影响。我们检测了EGFR mRNA和蛋白的基础水平，以及FSH和LH在转录和翻译水平上调控EGFR的机制。采用通过转染SV40 T抗原从正常OSE细胞衍生而来的永生化OSE细胞系（IOSE）（IOSE - 80和IOSE - 80PC，一种危机后细胞系）以及卵巢癌细胞系。与卵巢癌细胞系OVCAR - 3和SKOV - 3相比，在IOSE - 80和IOSE - 80PC细胞中均观察到EGFR水平显著较低。用FSH和LH（10⁻⁷和10⁻⁶ g/ml）处理IOSE - 80PC细胞24小时后，EGFR mRNA显著增加，48小时后EGFR蛋白显著增加，而用促性腺激素处理24 - 48小时在OVCAR - 3细胞中诱导EGFR轻度增加，但在SKOV - 3细胞中未观察到。此外，用促性腺激素和EGF（10 nM）处理的IOSE - 80PC细胞表现出有丝分裂的累加刺激作用。此外，FSH和LH在5 - 10分钟时显著增加了各种激酶的活性，用LY294002（PI3K抑制剂）或PD98059（ERK1/2抑制剂）预处理可部分阻断促性腺激素诱导的IOSE - 80PC细胞中EGFR的上调。我们研究了促性腺激素对EGFR mRNA水平的影响是由转录增加和/或mRNA稳定性改变所诱导的。用FSH（10⁻⁷和10⁻⁶ g/ml）处理IOSE - 80PC细胞24小时后，EGFR启动子活性显著增强（分别增加120%和140%），用LH（IOSE - 80PC细胞系（IOSE - 80和IOSE - 80PC，一种危机后细胞系）以及卵巢癌细胞系。与卵巢癌细胞系OVCAR - 3和SKOV - 3相比，在IOSE - 80和IOSE - 80PC细胞中均观察到EGFR水平显著较低。用FSH和LH（10⁻⁷和10⁻⁶ g/ml）处理IOSE - 80PC细胞24小时后，EGFR mRNA显著增加，48小时后EGFR蛋白显著增加，而用促性腺激素处理24 - 48小时在OVCAR - 3细胞中诱导EGFR轻度增加，但在SKOV - 3细胞中未观察到。此外，用促性腺激素和EGF（10 nM）处理的IOSE - 80PC细胞表现出有丝分裂的累加刺激作用。此外，FSH和LH在5 - 1给这些细胞中的EGFR启动子活性增加了30%。另一方面，LH导致EGFR mRNA稳定性在衰减曲线中显著增加。综上所述，这些结果表明，促性腺激素对EGFR表达的影响可能通过ERK - 1/-2和PI3K途径影响肿瘤前卵巢表面上皮细胞的生长，并且FSH和LH通过不同机制增加EGFR mRNA。前者主要增加EGFR基因转录，而后者主要增强EGFR mRNA稳定性。
