【佳學基因檢測】通過抑癌基因高甲基化組檢測尿液中的膀胱癌

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根據(jù)基因檢測結(jié)果分析中的基因解碼方法發(fā)現(xiàn)《Clin Cancer Res》在 2004 Mar 15;10(6):1887-93發(fā)表了一篇題目為《通過抑癌基因高甲基化組檢測尿液中的膀胱癌》腫瘤靶向藥物治療基因檢測臨床研究文章。該研究由Essel Dulaimi, Robert G Uzzo, Richard E Greenberg, Tahseen Al-Saleem, Paul Cairns等完成。該方法提供了一種高效、靈敏的通過尿液檢測膀胱癌的癌癥基因的檢測方法，是基因解碼促進了惡性膀胱癌早期診斷的一種更為方便的方法。

腫瘤靶向藥物及正確治療臨床研究內(nèi)容關(guān)鍵詞：

膀胱癌,抑癌基因,甲基化,高甲基化組,尿液基因檢測

腫瘤靶向治療基因檢測臨床應用結(jié)果

膀胱癌基因檢測的研究目的：膀胱癌在大多數(shù)情況下是可以治好的,然而，就診時患有晚期疾病的患者的預后仍然很差。當前的非侵入性測試（例如細胞學）缺乏足夠的靈敏度來檢測低級別、低階段的腫瘤。沉默腫瘤抑制基因，如 p16(INK4a)、VHL 和錯配修復基因 hMLH1，已確定啟動子高甲基化是人類癌癥中腫瘤抑制基因失活的常見機制。它也是一個有前途的新目標，用于在包括尿液在內(nèi)的體液中進行分子基因檢測。尿液是一種易于獲取的液體，已知含有膀胱癌細胞。甲基化特異性 PCR (MSP)基因檢測 可以在以1000 個未甲基化等位基因中存在 1 個甲基化等位基因的靈敏度水平確定基因位點甲基化的存在與否，適用于識別體液中的癌細胞 DNA。膀胱癌甲基化基因檢測的實驗設計：膀胱癌基因檢測技術(shù)研究小組首先通過亞硫酸氫鹽測序確定了 Rb 腫瘤抑制基因的高甲基化頻率，并通過甲基化特異性 PCR基因檢測確定了 45 種膀胱癌中 p16（INK4a）、p14（ARF）、APC 和 RASSF1A 抑癌基因的高甲基化頻率。然后，膀胱癌基因檢測設計團隊設計了一個由 APC、RASSF1A 和 p14(ARF) 腫瘤抑制基因組成的賊適合診斷覆蓋率的基因檢測包。對該組進行了測試，以檢測來自相同 45 名膀胱癌患者（2 名 Tis、16 名 Ta、10 名 T1 和 17 名 T2-4）以及正常和良性對照 DNA 在手術(shù)前獲得的尿液樣本中匹配的沉積物 DNA 中的高甲基化。結(jié)果：在所有 45 種腫瘤 DNA 中發(fā)現(xiàn)了至少一種抑制基因（APC、RASSF1A 和 p14(ARF)）的高甲基化（100% 的診斷覆蓋率）。膀胱癌基因檢測技術(shù)研究小組在 45 名患者中的 39 名（敏感性 87%）中檢測到匹配的尿液 DNA 中的基因高甲基化，其中包括 16 名細胞學陰性的病例。在正常移行細胞 DNA 或來自正常健康個體和炎癥性泌尿疾病（膀胱炎）患者的尿液 DNA 中未觀察到 APC、RASSF1A 或 p14(ARF) 的高甲基化。此外，腫瘤 DNA 中的未甲基化基因在匹配的尿液 DNA 中始終未甲基化（100% 特異性）。膀胱癌基因檢測技術(shù)研究小組結(jié)論：腫瘤抑制基因的啟動子高甲基化在膀胱癌中很常見，并且在所檢查的腫瘤的所有等級和階段中都存在。 45 名患者中有 39 名 (87%) 的尿液 DNA 中檢測到高甲基化，包括可治好的早期疾病病例。甲基化特異性 PCR基因檢測 可以使用非侵入性尿檢來增強膀胱癌的早期檢測。

腫瘤發(fā)生與反復轉(zhuǎn)移國際數(shù)據(jù)庫描述：

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.