【佳学基因检测】通过抑癌基因高甲基化组检测尿液中的膀胱癌

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根据基因检测结果分析中的基因解码方法发现《Clin Cancer Res》在 2004 Mar 15;10(6):1887-93发表了一篇题目为《通过抑癌基因高甲基化组检测尿液中的膀胱癌》肿瘤靶向药物治疗基因检测临床研究文章。该研究由Essel Dulaimi, Robert G Uzzo, Richard E Greenberg, Tahseen Al-Saleem, Paul Cairns等完成。该方法提供了一种高效、灵敏的通过尿液检测膀胱癌的癌症基因的无创检测方法，是基因解码促进了恶性膀胱癌早期诊断的一种更为方便的方法。

肿瘤靶向药物及精准治疗临床研究内容关键词：

膀胱癌,抑癌基因,甲基化,高甲基化组,尿液基因检测

肿瘤靶向治疗基因检测临床应用结果

膀胱癌基因检测的研究目的：膀胱癌在大多数情况下是可以治愈的,然而，就诊时患有晚期疾病的患者的预后仍然很差。当前的非侵入性测试（例如细胞学）缺乏足够的灵敏度来检测低级别、低阶段的肿瘤。沉默肿瘤抑制基因，如 p16(INK4a)、VHL 和错配修复基因 hMLH1，已确定启动子高甲基化是人类癌症中肿瘤抑制基因失活的常见机制。它也是一个有前途的新目标，用于在包括尿液在内的体液中进行分子基因检测。尿液是一种易于获取的液体，已知含有膀胱癌细胞。甲基化特异性 PCR (MSP)基因检测 可以在以1000 个未甲基化等位基因中存在 1 个甲基化等位基因的灵敏度水平确定基因位点甲基化的存在与否，适用于识别体液中的癌细胞 DNA。膀胱癌甲基化基因检测的实验设计：膀胱癌基因检测技术研究小组首先通过亚硫酸氢盐测序确定了 Rb 肿瘤抑制基因的高甲基化频率，并通过甲基化特异性 PCR基因检测确定了 45 种膀胱癌中 p16（INK4a）、p14（ARF）、APC 和 RASSF1A 抑癌基因的高甲基化频率。然后，膀胱癌基因检测设计团队设计了一个由 APC、RASSF1A 和 p14(ARF) 肿瘤抑制基因组成的最适合诊断覆盖率的基因检测包。对该组进行了测试，以检测来自相同 45 名膀胱癌患者（2 名 Tis、16 名 Ta、10 名 T1 和 17 名 T2-4）以及正常和良性对照 DNA 在手术前获得的尿液样本中匹配的沉积物 DNA 中的高甲基化。结果：在所有 45 种肿瘤 DNA 中发现了至少一种抑制基因（APC、RASSF1A 和 p14(ARF)）的高甲基化（100% 的诊断覆盖率）。膀胱癌基因检测技术研究小组在 45 名患者中的 39 名（敏感性 87%）中检测到匹配的尿液 DNA 中的基因高甲基化，其中包括 16 名细胞学阴性的病例。在正常移行细胞 DNA 或来自正常健康个体和炎症性泌尿疾病（膀胱炎）患者的尿液 DNA 中未观察到 APC、RASSF1A 或 p14(ARF) 的高甲基化。此外，肿瘤 DNA 中的未甲基化基因在匹配的尿液 DNA 中始终未甲基化（100% 特异性）。膀胱癌基因检测技术研究小组结论：肿瘤抑制基因的启动子高甲基化在膀胱癌中很常见，并且在所检查的肿瘤的所有等级和阶段中都存在。 45 名患者中有 39 名 (87%) 的尿液 DNA 中检测到高甲基化，包括可治愈的早期疾病病例。甲基化特异性 PCR基因检测 可以使用非侵入性尿检来增强膀胱癌的早期检测。

肿瘤发生与复发转移国际数据库描述：

Purpose: Bladder cancer is potentially curable in the majority of cases; however, the prognosis for patients with advanced disease at presentation remains poor. Current noninvasive tests such as cytology lack sufficient sensitivity to detect low-grade, low-stage tumors. Silencing of tumor suppressor genes, such as p16(INK4a), VHL, and the mismatch repair gene hMLH1, has established promoter hypermethylation as a common mechanism for tumor suppressor inactivation in human cancers. It is also a promising new target for molecular detection in bodily fluids including urine, a readily accessible fluid known to contain bladder cancer cells. Methylation-specific PCR (MSP) can determine the presence or absence of methylation of a gene locus at a sensitivity level of up to 1 methylated allele in 1000 unmethylated alleles, appropriate for identifying cancer cell DNA in a bodily fluid.Experimental design: We first determined the frequency of hypermethylation of the Rb tumor suppressor gene by bisulfite sequencing and of the p16(INK4a), p14(ARF), APC, and RASSF1A tumor suppressor genes by MSP in 45 bladder cancers. We then designed a panel optimal for diagnostic coverage composed of the APC, RASSF1A, and p14(ARF) tumor suppressor genes. This panel was tested for detection of hypermethylation in matched sediment DNA from urine specimens obtained before surgery from the same 45 bladder cancer patients (2 Tis, 16 Ta, 10 T1, and 17 T2-4) as well as normal and benign control DNAs.Results: Hypermethylation of at least one of three suppressor genes (APC, RASSF1A, and p14(ARF)) was found in all 45 tumor DNAs (100% diagnostic coverage). We detected gene hypermethylation in the matched urine DNA from 39 of 45 patients (87% sensitivity), including 16 cases that had negative cytology. No hypermethylation of APC, RASSF1A, or p14(ARF) was observed in normal transitional cell DNAs or in urine DNAs from normal healthy individuals and patients with inflammatory urinary disease (cystitis). Furthermore, an unmethylated gene in the tumor DNA was always found to be unmethylated in the matched urine DNA (100% specificity).Conclusions: Promoter hypermethylation of tumor suppressor genes is common in bladder cancer and was found in all grades and stages of tumors examined. Hypermethylation was detected in the urine DNA from 39 of 45 (87%) patients, including cases of early-stage disease amenable to cure. MSP may enhance early detection of bladder cancer using a noninvasive urine test.