Establishment of tumor maker test using tumor-derived nucleic acids in plasma

在B细胞淋巴系统恶性肿瘤中，恶性细胞单克隆增殖，具有相同的免疫球蛋白基因重排。这种重排可以通过使用聚合酶链反应（PCR）检测。最近，有报道通过PCR分析从B细胞恶性肿瘤患者血浆中提取的DNA可以证明克隆细胞的增殖。然而，问题是，在这项研究中，使用从同一B细胞白血病患者的恶性细胞和血浆中提取的DNA，我试图通过半定量PCR扩增免疫球蛋白重链（IgH）互补决定区3（CDR 3）。结果表明，血浆DNA与肿瘤细胞DNA的序列完全一致，这些结果表明，血浆DNA是从肿瘤细胞中释放出来的，下一步有必要提高灵敏度，如果成功，血浆DNA IgH-PCR可能成为诊断患者和评估治疗效果的有用工具，特别是在病情危重，任何活检都很困难的患者中。

In B cell lymphoid malignancies, malignant cells proliferate monoclonally with the same immunoglobulin gene rearrangement.This rearrangement can be detected by the use of the polymerase chain reaction(PCR).Recently, it has been reported that proliferation of clonal cells could be demonstrated by PCR analyzing DNA extracted from patients' plasma with B cell malignancies.The question, however, still remains whether amplified products were derived from tumor cells or not.In this study, using DNA extracted from both malignant cells and plasma of the same patients with B cell leukemia, I attempted to amplify immunoglobulin heavy chain(IgH) complementarity determining region 3(CDR3) by semi-nested PCR and to analyze the sequences respectively.The results showed that sequences of DNA from plasma were identical with that of DNA from tumor cells in all cases.In addition, some of them showed homology to CDR3 that was previously reported.These findings indicate that plasma DNA is released from tumor cells.In the next stage, it is necessary to raise the sensitivity, and if it works, IgH-PCR using plasma DNA might be useful tool for diagnosing patients and evaluating the efficacy of treatment, especially in patients with critical condition under which any biopsies were difficult.