Hugo F, Fischer G, Eigenbrodt E
Krankenhaus Nordwest, Zentrallabor, Frankfurt, Germany.
Anticancer Res. 1999 Jul-Aug;19(4A):2753-7.
The majority of tumors express an isoform of the glycolytic enzyme pyruvate kinase, the type tumor M2. The isoenzyme exists in an active tetrameric and a less active dimeric form. The dimeric form is strongly overexpressed in tumor cells and this new tumor marker is thus called tumor M2-PK. This isoenzyme is released from tumor cells and is quantitatively detectable in body fluids by a sensitive enzyme-linked immunosorbent assay (ELISA). To establish the ELISA for the routine diagnostic in a clinical laboratory, the sample stability was evaluated. Therefore, blood samples were collected in different ways from healthy donors. Reproducibility of tumor M2-PK detection in EDTA-plasma was not affected by the day to day 'stress' in a clinical routine (e.g. shaking, leaving the samples at room temperature for several hours without prior centrifugation). Similar results were obtained with citrate-plasma, whereas detection in serum and heparin-plasma was only reproducible when the blood samples were centrifuged within 2 hrs after collection. It appears that lymphocytes contain small amounts of the tumor M2-PK isoenzyme. They might release tumor M2-PK in heparin-plasma and serum samples, but not in EDTA-plasma samples. The results indicated that EDTA-plasma appears to be most appropriate for the routine diagnostic of tumor M2-PK as a tumor marker.
大多数肿瘤表达糖酵解酶丙酮酸激酶的一种同工型，即肿瘤M2型。该同工酶以活性四聚体和活性较低的二聚体形式存在。二聚体形式在肿瘤细胞中强烈过表达，因此这种新的肿瘤标志物被称为肿瘤M2-PK。这种同工酶从肿瘤细胞中释放出来，通过灵敏的酶联免疫吸附测定（ELISA）可在体液中进行定量检测。为在临床实验室建立用于常规诊断的ELISA，对样本稳定性进行了评估。因此，从健康供体以不同方式采集血样。在临床常规操作中，EDTA血浆中肿瘤M2-PK检测的重现性不受日常“应激”（如振荡、样本在室温下放置数小时而未预先离心）的影响。柠檬酸盐血浆也得到了类似结果，而血清和肝素血浆中的检测只有在血样采集后2小时内离心才具有重现性。似乎淋巴细胞含有少量肿瘤M2-PK同工酶。它们可能在肝素血浆和血清样本中释放肿瘤M2-PK，但不在EDTA血浆样本中释放。结果表明，EDTA血浆似乎最适合作为肿瘤标志物对肿瘤M2-PK进行常规诊断。
