2015-08-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/660292摘要：初步分析我們 181位 AML病人之微矩陣資料，濾得一個基因 HOPX，發現 HOPX表達量高者，預後愈差。再分析另外兩個獨立族群 TCGA與 GSE12417GPL96，也看到同樣現象。HOPX是最小的 Homeodomain蛋白，對動物之心臟發育不可或缺。研究顯示HOPX在很多固態腫瘤中有抑癌作用。在腸道、毛囊、造血幹細胞中有表達。除此之外，HOPX在造血系統中的角色則一無所知。我們也發現它與其他造血幹細胞基因 HOX cluster、MEIS1、MN1 有同步之表達趨勢，顯示 HOPX必定在維持幹細胞性質方面有重要功能。高 HOPX 表達可能促進 quiescence 而增加抗藥性。為了證實這個假說並進一步探討 HOPX在正常與惡性之造血系統中的影響，我們在未來三年將完成：(1)把人數擴展至 324人，待基因突變完成後，將更有信心得知 HOPX在 AML中之臨床與生理意義。(2)在正常之小鼠造血幹細胞中操作 Hopx 表達量，以得知 Hopx 在正常造血系統中之角色。(3)以MN1 及MLL-AF9 過度表達以得到 AML小鼠。在這樣的背景下操作 Hopx 表達量，以得知 Hopx 在 AML中的角色。由於 MN1、MLL-AF9、MEIS1、與HOX clusters在這兩種 AML之致病過程中息息相關，且 HOPX與這些基因之表達有同向趨勢，我們預期 HOPX對這兩種 AML之致病機轉必有重要影響。我們測試這些 AML之化療敏感度，以釐清 Hopx 對抗藥性之作用。我們相信這研究有助於解釋 HOPX對病人預後的影響，並了解 HOPX在正常與惡性造血系統中的角色。<br> Abstract: Aberrant gene expression and gene mutations underlie the pathogenesis of acute myeloid leukemia (AML). In our pilot screening of gene signatures of prognostic significance in AML through our microarray data derived from 181 patients, we noted higher expression of HOPX was strongly associated with poor survival. We further analyzed another two independent cohorts, TCGA and GSE12417GPL96, and got the same conclusion. HOPX encodes the shortest hemodomain protein, containing 73 amino acids with a molecular weight of 12 kd. It is essential for cardiac development in mice and zebrafish. Unlike other homeodomain proteins, HOPX doesn’t have DNA-binding domain; it exerts transcriptional regulation through sequestration of serum responsive factor and by recruiting HDAC2. Recent studies indicate a role of HOPX in tumor suppression in cancers of lung, colon, esophagus, pancreas, uterus, and stomach. HOPX appears to be a stem cell marker in intestine and hair follicles. In one study HOPX was among the top genes of leukemia stem cell signature. To get further insight of the pathophysiology of HOPX, we analyzed its associated gene signatures in our microarray data and noted a strong association between high HOPX levels with high expression of stem cell markers MN1, MEIS1, and HOX (HOXA5, A9, A10, B2) clusters, all of which are critical for regulation of normal and malignant hematopoiesis. These data strongly imply a role of HOPX in maintaining the stemness in hematopoiesis. Since stem cell signature is associated with unfavorable prognosis in AML, it’s possible that HOPX expression renders unfavorable prognosis through maintaining stemness. In this 3-year project, we will unravel the pathophysiology of Hopx in hematopoietic system by completing the following 3 tasks: (1) expanding our analysis to 324 patients, all of whom have complete mRNA array, clinical, and lab data except that some gene mutations are to be completed. With this larger cohort we will get more confident clinical and biological implications of HOPX. We will ask if HOPX gene promoter methylation is responsible for its expression. (2) interrogating the role of HOPX in normal hematopoiesis. We will over-express and knock down Hopx in normal mouse hematopoietic stem/progenitor cells, followed by in vitro and in vivo analyses to see how Hopx affects the normal hematopoiesis; (3) exploring the role of Hopx in leukemia background. We will generate MN1- and MLL-AF9-induced leukemia in mice, followed by over-expression and shRNA-mediated knockdown of Hopx to see if the Hopx levels affect leukemogenesis. MN1- and MLL-AF9-induced leukemia is related to aberrant expression of HOX gene cluster, MN1, and MEIS1. Moreover, our preliminary data point to concordant expression of HOPX, HOX cluster, MN1, and MEIS1. Thus we expect to see important impacts of HOPX in these two leukemia models. The sensitivity of leukemia cells in which over-expression and knockdown of Hopx can be tested in vivo to realize how Hopx levels influence sensitivity to chemotherapy. We believe this project will help us understand how HOPX expression affects survival of AML patients. We expect to get information of high impact to the field of Hematology.