Martinet N, Alla F, Farré G, Labib T, Drouot H, Vidili R, Picard E, Gaube M P, Le Faou D, Siat J, Borelly J, Vermylen P, Bazarbachi T, Vignaud J M, Martinet Y
Centre Lorrain d'Etudes et de Recherches sur les Cancers Pulmonaires, Faculté de Médecine, Vandoeuvre-Lès-Nancy, France.
Cancer Res. 2000 Jun 1;60(11):2869-75.
Smoking prevention will decrease lung cancer incidence in time. However, early detection would improve lung cancer prognosis in subjects at risk provided that specific markers could be identified. We previously reported that retinoic acid receptor (RAR) and retinoid X receptor (RXR) expression was altered in lung tumors. RAR-beta gene status could be derived from corresponding allelotyping and immunohistochemistry data. We now report the continued study on lung cancer precursor lesions. Fluorescence PCR-based assays were used for allelotyping at the RAR/RXR loci of: (a) 66 lung precursor lesions found at the free resection margins of 41 patients undergoing surgery for lung cancer (+ 31 paired tumors); and (b) bronchial cells also found at the free resection margins from 16 current and 8 never smokers operated on for noncancerous diseases. Three microsatellites located at 3p14-21 and 9p21 were also used for interwork comparison. Immunohistochemistry was additionally performed to evaluate P53 and RAR-beta expression in precursor lesions. Chi2 tests showed significant differences (P < 0.05) when comparing the results obtained from never smokers, smokers, squamous metaplasia, dysplasia + in situ carcinoma, and tumors. Microsatellite changes occurred frequently in all samples, but without specificity for any group (P < 0.08-0.52). They were globally correlated with tobacco exposure (P < 0.04), for which the RAR-gamma marker appeared as a preferential target (P < 0.004). Few reparation error phenotypes were observed, mostly at the RXR-alpha and RXR-gamma markers for which combined changes were also linearly increasing from never smokers to dysplasia + in situ carcinoma (P < 0.05 and P < 0.03). RAR-beta marker losses also increased from the first to the last group studied (P < 0.01), with a concomitant decrease in RAR-beta protein expression and correlated p53 increased immunoreactivity (P < 0.02). Losses at 3p14, 3p21, and P16 were frequent, but no significant differences between groups could be found. Unexpectedly, high constitutive homozygosity was observed near the RAR-alpha locus in squamous cell lung cancer cases. RARs/RXRs form homodimers or heterodimers involved in ligand binding. Their added alterations could result in a state of functional vitamin A deficiency in the affected bronchial cells. Further deletion events drawn from a limited repertoire of specific regions such as 3p14-21 and 9p21 could subsequently drive the deficient cells to invasive carcinoma.
预防吸烟将及时降低肺癌发病率。然而，倘若能够识别出特定标志物，早期检测将改善高危人群的肺癌预后。我们之前报道过，肺癌组织中维甲酸受体（RAR）和维甲酸X受体（RXR）的表达发生了改变。RAR-β基因状态可从相应的等位基因分型和免疫组化数据得出。我们现在报告对肺癌前体病变的持续研究。基于荧光PCR的检测方法用于对以下样本的RAR/RXR基因座进行等位基因分型：（a）在41例接受肺癌手术患者的游离手术切缘发现的66个肺前体病变（+31对肿瘤组织）；（b）在16例现吸烟者和8例从不吸烟者因非癌性疾病接受手术的游离手术切缘也发现的支气管细胞。位于3p14 - 21和9p21的三个微卫星也用于相互比较。另外进行免疫组化以评估前体病变中P53和RAR-β的表达。卡方检验显示，在比较从不吸烟者、吸烟者、鳞状化生、发育异常+原位癌和肿瘤组织的结果时存在显著差异（P<0.05）。微卫星变化在所有样本中频繁发生，但对任何组均无特异性（P<0.08 - 0.52）。它们总体上与烟草暴露相关（P<0.04），其中RAR-γ标志物似乎是一个优先靶点（P<0.004）。观察到很少的修复错误表型，主要出现在RXR-α和RXR-γ标志物上，其联合变化也从从不吸烟者到发育异常+原位癌呈线性增加（P<0.05和P<0.03）。RAR-β标志物缺失也从研究的第一组到最后一组增加（P<0.01），同时RAR-β蛋白表达降低，而相关的p53免疫反应性增加（P<0.02）。3p14、3p21和P16的缺失很常见，但组间未发现显著差异。出乎意料的是，在肺鳞状细胞癌病例中，在RAR-α基因座附近观察到高组成型纯合性。RARs/RXRs形成参与配体结合的同二聚体或异二聚体。它们额外的改变可能导致受影响的支气管细胞中功能性维生素A缺乏状态。从3p14 - 21和9p21等特定区域的有限基因库中进一步发生的缺失事件可能随后将缺陷细胞驱动为浸润性癌。
