Verri Carla, Roz Luca, Conte Davide, Liloglou Triantafillos, Livio Anna, Vesin Aurelien, Fabbri Alessandra, Andriani Francesca, Brambilla Christian, Tavecchio Luca, Calarco Giuseppe, Calabrò Elisa, Mancini Andrea, Tosi Diego, Bossi Paolo, Field John K, Brambilla Elisabeth, Sozzi Gabriella
Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
Am J Respir Crit Care Med. 2009 Mar 1;179(5):396-401. doi: 10.1164/rccm.200807-1153OC. Epub 2008 Dec 18.
Fragile histidine triad (FHIT) is a tumor suppressor gene involved in the pathogenesis of lung cancer.
The purpose of this study was to investigate the different molecular alterations leading to the inactivation of FHIT gene function and to validate their use as biomarkers of risk for progression of the disease in patients belonging to the multicentric European study for the Early detection of Lung Cancer (EUELC) who were resected for early-stage lung tumors.
FHIT immunostaining was performed on 305 tumor samples. The methylation status of FHIT promoter was assessed by nested methylation-specific polymerase chain reaction (MSP-PCR) in 232 tumor and 225 normal lung samples of which a subset of 187 patients had available normal/tumor DNA pairs. Loss of heterozygosity (LOH) at the FHIT locus was analyzed in 202 informative cases by D3S1300 and D3S1234 microsatellite markers.
Lost or reduced FHIT expression was found in 36.7 and 75.7% of the tumor samples, respectively. Methylation of the FHIT promoter was found in 36.7% of tumor and 32.7% of normal lung samples, whereas LOH was detected in 61.9% of the tumors. A strong association with complete loss of FHIT expression was present when methylation and LOH were analyzed together (P = 0.0064). Loss of FHIT protein expression was significantly more frequent in squamous cell carcinoma histotype (P < 0.0001) and in smokers (P = 0.008). FHIT methylation in normal lung was associated with an increased risk of progressive disease (OR, 2.27; P = 0.0415).
Our results indicate that different molecular mechanisms interplay to inactivate FHIT expression and support the proposition that FHIT methylation in normal lung tissue could represent a prognostic marker for progressive disease.
脆性组氨酸三联体（FHIT）是一种参与肺癌发病机制的肿瘤抑制基因。
本研究旨在调查导致FHIT基因功能失活的不同分子改变，并验证其作为疾病进展风险生物标志物在多中心欧洲肺癌早期检测研究（EUELC）中接受早期肺癌肿瘤切除术患者中的应用。
对305个肿瘤样本进行FHIT免疫染色。通过巢式甲基化特异性聚合酶链反应（MSP-PCR）评估232个肿瘤样本和225个正常肺样本中FHIT启动子的甲基化状态，其中187例患者有可用的正常/肿瘤DNA对。通过D3S1300和D3S1234微卫星标记分析202例信息丰富病例中FHIT基因座的杂合性缺失（LOH）。
分别在36.7%和75.7%的肿瘤样本中发现FHIT表达缺失或降低。在36.7%的肿瘤样本和32.7%的正常肺样本中发现FHIT启动子甲基化，而在61.9%的肿瘤中检测到LOH。当一起分析甲基化和LOH时，与FHIT表达完全缺失存在强关联（P = 0.0064）。FHIT蛋白表达缺失在鳞状细胞癌组织学类型中显著更常见（P < 0.0001），在吸烟者中也更常见（P = 0.008）。正常肺组织中的FHIT甲基化与疾病进展风险增加相关（OR，2.27；P = 0.0415）。
我们的结果表明，不同的分子机制相互作用使FHIT表达失活，并支持正常肺组织中FHIT甲基化可代表疾病进展预后标志物的观点。
