Doraiswamy V, Parrott J A, Skinner M K
Center for Reproductive Biology, School of Molecular Biosciences, Washington State University, Pullman, Washington 99163-4231, USA.
Biol Reprod. 2000 Sep;63(3):789-96. doi: 10.1095/biolreprod63.3.789.
Greater than 95% of ovarian cancers originate in the epithelial cells on the surface of the ovary. The current study investigates the expression and action of transforming growth factor alpha (TGFalpha) in ovarian surface epithelium (OSE) and the underlying stroma in both normal and tumorigenic ovarian tissues. Normal bovine ovaries are used in the current study as a model system to investigate normal OSE functions. Transforming growth factor alpha and its receptor, the epidermal growth factor receptor (EGFR), were detected in the OSE from normal ovaries by immunocytochemistry (ICC). Ovarian stromal tissue also contained reduced but positive TGFalpha and EGFR immunostaining. To examine TGFalpha and EGFR gene expression, RNA was collected from normal bovine OSE and ovarian stromal cells. The TGFalpha and EGFR transcripts were detected in both fresh and cultured OSE and stromal cells by a sensitive quantitative reverse transcription polymerase chain reaction (QRT-PCR) assay. Transforming growth factor alpha gene expression was found to be high in freshly isolated OSE, but low in freshly isolated stroma. In contrast, EGFR expression was higher in the stroma compared to the OSE. Both the ICC and QRT-PCR indicate that normal OSE express high levels of TGFalpha in vivo and in vitro. In vitro, normal ovarian stromal cells develop the capacity to express high levels of EGFR. Human ovarian tumors from stage II, stage III, and stage IV ovarian cancer cases were found to express TGFalpha and EGFR protein in the epithelial cell component of the tumor by ICC analysis. The stromal cell component of human ovarian tumors contained little or no TGFalpha/EGFR immunostaining. Observations suggest that tumor progression may in part require autocrine stimulation of the epithelia. Transforming growth factor alpha was found to stimulate the growth of normal bovine OSE and stroma cells to the same level as epidermal growth factor. Two ovarian cancer cell lines, SKOV3 and OCC1, were also stimulated to proliferate in response to TGFalpha. Transforming growth factor alpha was also found to stimulate the expression of two growth factors previously shown to be produced by OSE. Transforming growth factor alpha stimulates both kit ligand/stem cell factor and keratinocyte growth factor production by OSE. The effect of hormones on TGFalpha and EGFR expression by the OSE was also examined. Human chorionic gonadotropin stimulated TGFalpha expression, but not FSH. Both hCG and FSH stimulated EGFR expression by OSE. Combined observations suggest a role of systemic hormones and a locally produced growth factor, TGFalpha, in OSE biology. Insight is also provided into how the OSE may develop abnormal growth characteristics involved in the onset and progression of ovarian cancer.
超过95%的卵巢癌起源于卵巢表面的上皮细胞。本研究调查了转化生长因子α（TGFα）在正常和致瘤性卵巢组织的卵巢表面上皮（OSE）及下方基质中的表达和作用。本研究使用正常牛卵巢作为模型系统来研究正常OSE的功能。通过免疫细胞化学（ICC）在正常卵巢的OSE中检测到了转化生长因子α及其受体表皮生长因子受体（EGFR）。卵巢基质组织中TGFα和EGFR免疫染色也呈弱阳性。为了检测TGFα和EGFR基因表达，从正常牛OSE和卵巢基质细胞中收集RNA。通过灵敏的定量逆转录聚合酶链反应（QRT-PCR）检测新鲜和培养的OSE及基质细胞中的TGFα和EGFR转录本。发现新鲜分离的OSE中TGFα基因表达高，而新鲜分离的基质中低。相反，与OSE相比，基质中EGFR表达更高。ICC和QRT-PCR均表明正常OSE在体内和体外均表达高水平的TGFα。在体外，正常卵巢基质细胞具有表达高水平EGFR的能力。通过ICC分析发现，来自II期、III期和IV期卵巢癌病例的人卵巢肿瘤在肿瘤上皮细胞成分中表达TGFα和EGFR蛋白。人卵巢肿瘤的基质细胞成分几乎没有或没有TGFα/EGFR免疫染色。观察结果表明肿瘤进展可能部分需要上皮细胞的自分泌刺激。发现转化生长因子α刺激正常牛OSE和基质细胞生长，其程度与表皮生长因子相同。两种卵巢癌细胞系SKOV3和OCC1也对TGFα刺激有增殖反应。还发现转化生长因子α刺激OSE先前显示产生的两种生长因子的表达。转化生长因子α刺激OSE产生kit配体/干细胞因子和角质形成细胞生长因子。还研究了激素对OSE中TGFα和EGFR表达的影响。人绒毛膜促性腺激素刺激TGFα表达，但不刺激FSH。hCG和FSH均刺激OSE表达EGFR。综合观察结果表明，全身激素和局部产生的生长因子TGFα在OSE生物学中起作用。还深入了解了OSE如何发展出与卵巢癌发生和进展相关的异常生长特征。
