急性骨髓性白血病相關生物指標之探索

Abstract

急性骨髓性白血病（AML）是一種造血細胞發生變異導致的疾病。由於AML在血液腫瘤中具有高發生率及低存活率，發展生物指標幫助臨床診斷及預後評估，顯得相當重要。本研究從血管新生作用及幹細胞調控機制兩方向，希望尋找合適之AML生物指標。共收集52名剛發病的AML患者，與20名正常骨髓捐贈者，以酵素免疫分析法測量骨髓血漿中的蛋白濃度。 骨髓中的血管新生作用，被認為和AML的致病機轉有關。本研究討論的血管新生因子，主要來自和血管新生最有關的vascular endothelial growth factor（VEGF）家族和angiopoietin（Ang）家族。共有VEGF-A、VEGF/PlGF、VEGF-C、VEGF-D、Ang-1、Ang-2、Tie-2七種。和正常對照相比，骨髓血漿中的VEGF/PlGF、Ang-2、Tie-2的濃度在AML病患顯著升高，VEGF-C與Ang-1濃度則顯著降低。以31名經過治療的病患進行存活分析，發現Ang-2和Tie-2濃度低、VEGF/PlGF和VEGF-D濃度高的AML病患，有較佳的預後。更進一步以上述四項因子，建立血管新生係數（angio-index），計算公式為(Ang-2×Tie-2)/(VEGF/PlGF×VEGF-D)。使用存活及迴歸分析都觀察到，血管新生係數較高的病患，有較差的預後。 在骨髓利基（bone marrow niche）中，造骨蛋白osteopontin（OPN）扮演維持造血幹細胞靜止狀態的角色，同時也可負向調控其生長及活性。本研究發現，OPN的濃度在AML病患較正常對照顯著增加。在31名進行存活分析的病患中，低OPN濃度者有較好的一年存活率。多變項迴歸分析則顯示，不論在一年或五年的追蹤，高OPN濃度之病患都有較差的預後。 綜合以上結果，本研究為AML的診斷及預後評估，提供了相當好的指標。對於今後的生物指標發展，也提出新的方向。

Acute myeloid leukemia (AML) is a heterogenous clonal disorder of hematopoietic cells. Because AML has high incidence rate and low survival probability among hematopoietic malignancies, it is important to develop biomarkers for clinical diagnosis and prognosis prediction. In the present study, AML biomarkers were estimated from two directions, angiogenesis and stem cell regulation. Bone marrow (BM) plasma from 52 AML patients before chemotherapy and 20 healthy controls were included, and protein concentrations were detected by ELISA. Angiogenesis in BM was thought to correlate with pathogenesis of AML. Vascular endothelial growth factor (VEGF) and angiopoietin (Ang) are the two families involved in the angiogenesis. Seven angiogenic factors were investigated in this study: VEGF-A, VEGF/PlGF, VEGF-C, VEGF-D, Ang-1, Ang-2, and Tie-2. Comparing to normal controls, the marrow levels of VEGF/PlGF, Ang-2, and Tie-2 were significantly higher, and those of VEGF-C and Ang-1 were significantly lower in the AML patients. Thirty-one patients were further subjected to survival analysis. Patients with lower Tie-2 and Ang-2 levels displayed a survival advantage, same as patients with higher VEGF/PlGF and VEGF-D levels. An angio-index [(Ang-2×Tie-2)/(VEGF/PlGF×VEGF-D)] was established. Both survival analysis and Cox regression models revealed that patients with higher angio-index values displayed poor prognosis Osteopontin (OPN) appears to maintain hematopoietic stem cells quiescence in BM niche and to negatively regulate their proliferation and activity. The marrow OPN levels were significantly higher in AML patients than those in healthy controls. Of the 31 patients subjected to survival analysis, those with lower OPN displayed a longer survival time in one-year analysis. Multivariate Cox regression models revealed patients with higher OPN level displayed poor prognosis in both one-year and five-year analysis. As a summary, this study provided good biomarkers for AML diagnosis and prognosis. It also showed new directions for AML biomarker discovery.