Pergolizzi R, Appierto V, Crosti M, Cavadini E, Cleris L, Guffanti A, Formelli F
Chemoprevention Unit, Istituto Nazionale Tumori, Milan, Italy.
Int J Cancer. 1999 May 31;81(5):829-34. doi: 10.1002/(sici)1097-0215(19990531)81:5<829::aid-ijc26>3.0.co;2-3.
The role of retinoic acid receptor (RAR) expression in sensitivity to N-(4-hydroxyphenyl)retinamide (4HPR or fenretinide) as well as on the tumorigenicity of human ovarian carcinoma cells was examined. Two human ovarian cancer cell lines, A2780 and IGROV-1, with a 10-fold difference in sensitivity to 4HPR were chosen to study RAR involvement in the response to 4HPR. To determine which RAR was effective, RARalpha, beta and gamma were individually overexpressed in A2780 cells, which are the most sensitive to 4HPR. Sensitivity to 4HPR was increased in RARbeta-overexpressing clones, whereas it was slightly decreased in RARalpha transfectants (which had diminished RARbeta expression) and was unchanged in clones transfected with RARgamma. IGROV-1 cells, which are RARbeta negative, were transfected with RARbeta. Surprisingly, none of the obtained IGROV-1 RARbeta transfectants expressed RARbeta protein, in spite of RARbeta mRNA transcription. All clones were similar to the parental IGROV-1 cells in their sensitivity to 4HPR. Treatment with a pharmacologically achievable concentration of 4HPR (1 microM) led to a rapid 2-fold increase in RARbeta mRNA levels in A2780 cells, but it did not induce RARbeta expression in IGROV-1 cells. Analysis of the tumorigenicity of A2780-transfected clones revealed that overexpression of RARalpha was associated with a significant reduction in tumor takes (50% and 67%, respectively, vs. 96% for the parent line) and with a reduced growth rate. Oncogenicity was clearly decreased in only 1 of the 2 RARbeta-overexpressing clones (33% takes) and was unchanged in the 2 clones with increased RARgamma expression. Our results demonstrate that basal expression and 4HPR inducibility of RARbeta play a role in mediating 4HPR response in ovarian cancer cells. The findings of reduced oncogenicity of clones overexpressing RARalpha and of one clone overexpressing RARbeta indicate that RARalpha and RARbeta might have a tumor-suppressive effect in ovarian tumors.
研究了视黄酸受体（RAR）表达在对N-（4-羟苯基）视黄酰胺（4HPR或非瑞司他）敏感性以及对人卵巢癌细胞致瘤性方面的作用。选择了对4HPR敏感性相差10倍的两种人卵巢癌细胞系A2780和IGROV-1，以研究RAR在对4HPR反应中的作用。为了确定哪种RAR起作用，分别在对4HPR最敏感的A2780细胞中过表达RARα、β和γ。在过表达RARβ的克隆中对4HPR的敏感性增加，而在RARα转染子（其RARβ表达减少）中敏感性略有降低，在用RARγ转染的克隆中敏感性未改变。对RARβ阴性的IGROV-1细胞转染RARβ。令人惊讶的是，尽管有RARβ mRNA转录，但所有获得的IGROV-1 RARβ转染子均未表达RARβ蛋白。所有克隆对4HPR的敏感性与亲代IGROV-1细胞相似。用药理学可达到的浓度4HPR（1μM）处理导致A2780细胞中RARβ mRNA水平迅速增加2倍，但未在IGROV-1细胞中诱导RARβ表达。对A2780转染克隆的致瘤性分析表明，RARα的过表达与肿瘤发生率的显著降低（分别为50％和67％，而亲代细胞系为96％）以及生长速率降低有关。在2个过表达RARβ的克隆中只有1个克隆的致癌性明显降低（发生率为33％），而在2个RARγ表达增加的克隆中致癌性未改变。我们的结果表明，RARβ的基础表达和4HPR诱导性在介导卵巢癌细胞对4HPR的反应中起作用。过表达RARα和一个过表达RARβ的克隆致癌性降低的结果表明，RARα和RARβ可能在卵巢肿瘤中具有肿瘤抑制作用。
