Abstract: Expression and Clinical Significance of Axl in Acute Myeloid LeukemiaFanghui ZHOU, Juan FAN, Liping HAN, XinWANG, RuiWANG, Ying LICorrespondence to: Juan FAN, E-mail: fanjuan@medmail.com.cnDepartment of Hematology, Provincial Hospital Affiliated to Shandong University, Ji'nan 250021, ChinaThis work was supported by a grant from the: Science and Technology Development Program of Shandong Province (No.2007GG30002013)Abstract Objective: To explore the effects of receptor tyrosine kinase Axl on acute myeloid leukemia ( AML ) and to examine theexpression of Axl. Method: Real-time quantitative reverse-transcription polymerase chain reaction ( RQ-RT-PCR ) was used to detect AxlmRNA expression in bone marrow cells from 24 patients recently diagnosed with AML, 11 relapsed/refractory patients, 12 patients incomplete remission ( CR ) and 11 controls. The correlation of Axl expression with clinical remission rates was also examined. Results: ①The median mRNA expression of Axl in the 24 recently diagnosed patients and 11 relapsed/refractory patients was much higher than thatin the controls ( Z = -2.791, -2.310, P < 0.05 ). Furthermore, the Axl expression in relapsed/refractory patients was higher than in recentlydiagnosed patients (Z = -2.239, P = 0.025 ). The expression of Axl was much higher in recently diagnosed patients than in the CR group (Z = -1.956, P = 0.040). No statistical difference was found between the CR group and the control group ( Z = -0.895, P = 0.325). ②Therewas no correlation of Axl mRNA expression with gender, age, peripheral WBC ( white blood cell ) counts, bone marrow blast percentage,chromosome karyotypes and immunophenotype in recently diagnosed patients ( P > 0.05 ). ③After two courses of chemotherapy, the levelof Axl mRNA was much higher in the relapsed/refractory group than in the CR group ( Z = -3.465, P = 0.001 ). Conclusion: The level ofAxl mRNA expression is closely related to multidrug resistance and development of AML.Keywords Acute leukemia; Axl mRNA; Multidrug resistance; RQ-RT-PCR