Waridel F, Estreicher A, Bron L, Flaman J M, Fontolliet C, Monnier P, Frebourg T, Iggo R
Oncogene Group, Swiss Institute for Experimental Cancer Research (ISREC), Epalinges.
Oncogene. 1997 Jan 16;14(2):163-9. doi: 10.1038/sj.onc.1200812.
Field cancerisation of the aerodigestive tract is caused by chronic exposure to alcohol and tobacco, but the nature of the genetic alterations preceding overt malignancy is unknown. To identify potential field changes we have used a functional assay which tests the transcriptional competence of human p53 expressed in yeast. To increase the sensitivity and reliability of the technique for samples containing under 20% mutant p53, the 5' and 3'-ends of the p53 cDNA were examined separately. With this split form of the assay the tissue p53 mRNA acts as its own control for RNA quality. Mutations were detected in 87% (46/53) of tumours, reflecting the high sensitivity of the technique. Multiple biopsies of histologically normal tissue from the upper aero-digestive tract were tested and clonal p53 mutations were identified in 76% (38/50) of biopsies from patients presenting with multiple tumours compared with 32% (38/117) of biopsies from patients presenting with single tumours (P<0.000001). All patients (16/16) presenting with multiple tumours had at least one positive biopsy, compared with only 53% (19/36) of patients presenting with single tumours (P <0.001). This defines expansion of multiple clones of mutant p53-containing cells as an important biological mechanism of field cancerisation, and provides a means to identify patients likely to benefit from intensive screening for the development of new head and neck tumours.
上呼吸道和消化道的场癌化是由长期接触酒精和烟草引起的，但在明显恶变之前的基因改变的性质尚不清楚。为了识别潜在的场变化，我们使用了一种功能测定法，该方法测试在酵母中表达的人p53的转录能力。为了提高该技术对含有低于20%突变型p53的样品的敏感性和可靠性，分别检查了p53 cDNA的5'和3'末端。采用这种分裂形式的测定法，组织p53 mRNA可作为其自身RNA质量的对照。在87%（46/53）的肿瘤中检测到突变，这反映了该技术的高敏感性。对上呼吸道和消化道组织学正常组织进行多次活检，结果显示，与单发肿瘤患者活检样本中的32%（38/117）相比，多发肿瘤患者活检样本中的76%（38/50）检测到克隆性p53突变（P<0.000001）。所有多发肿瘤患者（16/16）至少有一次活检呈阳性，而单发肿瘤患者中只有53%（19/36）的患者活检呈阳性（P<0.001）。这表明含有突变型p53的细胞的多个克隆的扩增是场癌化的一种重要生物学机制，并提供了一种手段来识别可能从密集筛查中受益的患者，以预防新的头颈肿瘤的发生。
