结直肠癌是一种常见的胃肠道恶性肿瘤。氨基酸代谢物的变化与肿瘤发生和疾病进展有关。基于手性氨基酸的生物标志物,尤其是D-氨基酸,尚未确定CRC的早期诊断。手性氨基酸的定量,特别是很低浓度的内源性D-氨基酸,在技术上具有挑战性。我们在这里报告了从115名CRC患者和155名健康志愿者收集的尿液样本中L-和D-氨基酸的定量。使用改进的方法。手性标记方法,液相色谱法,和串联质谱能够分离和检测28个氨基酸(14个L-氨基酸,13个D-氨基酸和Gly)。正交偏最小二乘判别分析鉴定了这些手性氨基酸中的14个目标变量,其将CRC与健康对照区分开。二元logistic回归分析显示D-α-氨基丁酸(D-AABA)、L-丙氨酸(L-Ala),D-丙氨酸(D-Ala),D-谷氨酰胺(D-Gln)和D-丝氨酸(D-Ser)可能是CRC的潜在生物标志物。组合多变量的受试者工作特征曲线分析导致曲线下面积(AUC)为0.995,灵敏度为98.3%,特异性为96.8%。用D-AABA构建的模型,D-Ala,D-Gln,和D-Ser达到0.988的AUC,表明D-氨基酸对与CRC关联的重要贡献。进一步分析还表明,代谢异常与年龄和CRC的发展有关。在50岁以上的CRC患者中,D-蛋氨酸(D-Met)降低,IV期患者的D/L-Gln高于I期患者。这项研究提供了尿样中D-氨基酸的特征,并为开发CRC的非侵入性诊断提供了有希望的策略。
Colorectal cancer (CRC) is a common malignant tumor in the gastrointestinal tract. Changes in amino acid metabolites have been implicated in tumorigenesis and disease progression. Biomarkers on the basis of chiral amino acids, especially D-amino acids, have not been established for early diagnosis of CRC. Quantification of chiral amino acids, especially very low concentrations of endogenous D-amino acids, is technically challenging. We report here the quantification of L- and D-amino acids in urine samples collected from 115 CRC patients and 155 healthy volunteers, using an improved method. The method of chiral labeling, liquid chromatography, and tandem mass spectrometry enabled separation and detection of 28 amino acids (14 L-amino acids, 13 D-amino acids and Gly). Orthogonal partial least squares discriminant analysis identified 14 targeted variables among these chiral amino acids that distinguished the CRC from the healthy controls. Binary logistic regression analysis revealed that D-α-aminobutyric acid (D-AABA), L-alanine (L-Ala), D-alanine (D-Ala), D-glutamine (D-Gln) and D-serine (D-Ser) could be potential biomarkers for CRC. A receiver operating characteristic curve analysis of combined multi-variables contributed to an area under the curve (AUC) of 0.995 with 98.3 % sensitivity and 96.8 % specificity. A model constructed with D-AABA, D-Ala, D-Gln, and D-Ser achieved an AUC of 0.988, indicating important contributions of D-amino acids to the association with CRC. Further analysis also demonstrated that the metabolic aberration was associated with age and the development of CRC, D-methionine (D-Met) was decreased in CRC patients with age over 50, and D/L-Gln in patients at stage IV was higher than patients at stage I. This study provides the signature of D-amino acids in urine samples and offers a promising strategy for developing non-invasive diagnosis of CRC.