Expression And Significance Of Galectin-3 In Acute Myeloid Leukemia

[Background]Acute myeloid leukemia is a malignant clonal disease of hematopoietic stem cells, and it is a highly heterogeneous disease group. With the exception of a few special types of acute myeloid leukemia, most patients with acute myeloid leukemia have low long-term survival rate and poor prognosis. On the clinical, age, initial white blood cell and platelet levels, and abnormal complex karyotype were all the factors of the prognosis in patients with acute myeloid leukemia. APL is a specific subtype of AML with balanced reciprocal translocation t (15;17)(q22;21). Prognosis of APL has significantly improved due to the application of ATRA and arsenic trioxide. However, early death and relapse are still the two major obstacles of long-term survival in patients with APL. With the continuous development of molecular technology, we found that a variety of molecular biological changes can affect the prognosis of patients with acute myeloid leukemia. Some molecular markers (such as FLT3, NPM1, CEBPA, c-KIT, etc.) are very important for risk assessment and prognosis of newly diagnosed acute myeloid leukemia, and even can be used as an important reference index for treatment decision.Galectin-3, encoded by LGALS3 (14q21-22), is a member of the galactoside-binding protein family, which includes three domains:NH2 terminal binding domain, sugar domain recognition domain, and a specific domain containing glycine, proline and tyrosine repeat sequences. Galectin-3 is a multifunctional protein implicated in a variety of biological functions, including tumo rcell adhesion, proliferation, differentiation, angiogenesis, apoptosis, cancer progression, and metastasis. Galectin-3 is secreted by normal cells and tumor cells, and can be detected in serum and plasma. The concentration of Galectin-3 in serum of patients with metastatic tumor was significantly higher than that of local tumor. At present, Galectin-3 is considered as an important indicator to assess the severity of malignant tumor and heart failure. High expression of Galectin-3 was detected in many solid tumors, which can lead to less sensitivity to chemotherapy, higher recurrence rate, shorter survival time, and poorer prognosis. Therefore, Galectin-3 acts as a prognostic indicator in many solid tumors including thyroid cancer, gastric cancer, colon cancer, mammary cancer. Different from other types of galectin molecules, Galectin-3 is the only anti-apoptotic protein in the lectin family. Galectin-3 can provide shelter for leukemia cells, and its high expression can inhibit the apoptosis of leukemic cells and induced multidrug resistance in leukemia cells. Galectin-3 protein levels were significantly increased in patients with non Hodgkin's lymphoma (NHL) including diffuse large B cell lymphoma (DLBCL) and primary effusion lymphoma (PEL) and Multiple myeloma (MM). High expression of Galectin-3 can resist the Fas-induced apoptosis, which plays an important role in the immune escape mechanism of tumor cells. High expression of Galectin-3 in chronic myeloid leukemia (CML) can enhance the proliferation and chemotaxis of leukemic cells, and induce the drug resistance of leukemia cells. Cheng et al reported that the expression of Gal-3 may be one of the independent prognostic factors of AML. With the further research of Galectin-3 in hematologic neoplasms, the research on the anti-tumor drug targeting Galectin-3 has been also widely carried out. GCS-100, as a Galectin-3 antagonist, which is extracted from citrus pectin, have played an exciting role in the treatment of multiple myeloma, lymphoma and chronic lymphocytic leukemia and other diseases. Studies showed that GCS-100, which had no obvious toxicity and more significant effect in vivo, can promote the development of T cells and the immune system to fight the cancer cells, and avoid the occurrence of multidrug resistance in combination with traditional chemotherapy drugs or other molecular targeted agents. There is no report on the correlation between Galectin-3 and blood tumor in China.[Objective]This study discussed the correlation between Galectin-3 and acute myeloid leukemia including APL, in order to find the new molecular prognostic indicators, improve the molecular prognostic scoring system, provide the help for the choice of treatment in newly diagnosed AML, and supply new ideas for biological targeted therapy.[Methods]1. Patients Selection of 298 patients with acute myeloid leukemia,108 patients with acute promyelocytic leukemia as the research object. Diagnosis and classification were carried out according to the classification and diagnostic criteria of FAB and WHO. Strictly comply with the inclusion and exclusion criteria. In addition, 30 normal persons were selected as control group.2. Measurement of serum Galectin-3 The expression levels of serum Galectin-3 in the patients group and control group were detected by enzyme linked immunosorbent assay (ELISA). The operation procedure is carried out strictly according to the specification of ELISA kit.3. Retrospective analysis of clinical data Retrospective analysis of clinical data of all patients with newly diagnosed and sequential treatment. Analyze the correlation of Galectin-3 protein expression and clinical features, clinical stage, the results of laboratory tests and therapeutic effect of the patients.4. Follow-up Out of hospital patients were followed up by telephone, few by visits. The mean follow-up period was 25.8 months in patients with non-M3 acute myeloid leukemia, and the mean follow-up period was 30.3 months in patients with acute promyelocytic leukemia.5. Statistical analysis SPSS20.0 software was used for statistical analysis, t test was used to compare the mean value between the two groups, the rate of the test using chi square test sample size for a little while using Fisher's exact test),<0.05, the difference was statistically significant. Survival analysis was done by the Kaplan-Meier method, univariate analysis by Log-rank test and multivariate analysis by Cox proportional hazard model, respectively.[Results]1. Expression of Galectin-3 protein in serumThe level of serum Galectin-3 protein in patients with non M3 acute myeloid leukemia was significantly higher than that in normal control (5.40±4.31 vs 2.21±1.84 ng/ml;P<0.001). The level of serum Galectin-3 is highest in M5 subtype, but lowest in M1 subtype. Galectin-3 protein levels were significantly decreased in all patients with acute myeloid leukemia during complete remission (P<0.001), and the level of Galectin-3 expression was significantly increased (P=0.048), but there was no significant difference between recurrence and initial diagnosis.The level of serum Galectin-3 protein in patients with acute promyelocytic leukemia was significantly higher than that in normal controls (4.09±2.25 vs 2.21±1.84 ng/ml; P<0.001), but was significantly lower than that in non M3 patients with acute myeloid leukemia (P=0.003).2. Correlation between Galectin-3 expression level and clinical characteristics and laboratory indexes of patientsIn the non-M3 acute myeloid leukemia research group, patients with Galectin-3 high expression were older (P<0.001), serum lactate dehydrogenase (LDH) levels were lower (P=0.036), cytogenetic abnormalities were more common (P=0.032), and the incidence of CEBPA double mutations was lower (P=0.016). But in sex, initial peripheral blood white blood cell count, hemoglobin level, platelet levels, serum ferritin, percentage of bone marrow blast cells and other molecular abnormalities including AML1/ETO, FLT3-ITD, NPM1, c-KIT, FLT3-TKD and WT1, there was no significant differences between 2 groups.In the study group of patients with acute promyelocytic leukemia, patients with Galectin-3 high expression were older (P<0.001), with psoriasis history (P=0.036), newly diagnosed with abnormal blood coagulation mechanism (P=0.042), and positively correlated with the CD34 expression (P=0.004).3. Correlation between Galectin-3 and clinical prognosisIn the non-M3 acute myeloid leukemia research group, the CR rate of Galectin-3 high expression group was significantly lower (57.1% vs 80.2%; P=0.001), and the rate of 1-year-OS was significantly lower (66.2% vs 88.5%; P=0.002), and the 1-year cumulative relapse was significantly higher than the lower expression group (P=0.001). But there were no significant differences in the rate of PR, the rate of induced mortality and the 3-year cumulative incidence of relapse (P>0.05) between the two groups, and there was also no significant difference in the rate of 3-year-OS (26% vs 28.5%;P=0.75). Survival curves showed that the survival time of Galectin-3 high expression group was significantly shorter than that in low expression group (?=0.009), and the difference was more significant in the patients with normal karyotype (P-0.005). This study demonstrated that Galectin-3 overexpression in AML1/ETO patients may predict poor prognosis. The research constructs Cox proportion risk model including age, initial WBC, Galectin-3, karyotype and molecular abnormalities (AML1/ETO, NPM1/FLT3-ITD, c-KIT, CEBPA, FLT3-TKD, WT1). Multivariate Cox regression analysis indicated that Galectin-3 was an independent adverse factor for OS in patients with non-M3 acute myeloid leukemia (hazard ratio (HR) 1.81,95% confidence interval (CI) 1.233-2.658; P=0.002). For patients with normal karyotype, high expression of Galectin-3 is still an independent unfavorable factor for OS. According to the Cox proportional hazards model results, a multi-factors risk scoring system including age, initial WBC, karyotype, Galectin-3, NPM1/FLT3-ITD, CEBPAdouble-mutation, c-KIT and WT1 mutations was formed to evaluate the prognosis of patients with non-M3 AML.In the study group of patients with acute promyelocytic leukemia, The 1-year-RFS rate of Galectin-3 high expression group was significantly lower than that of the low expression group (86.9% vs 96.2%; p=0.04). Although the CR rate of Galectin-3 high expression group was lower (83.7% vs 91.2%), and the mortality rate was higher (14.3% vs 7%), the recurrence rate was higher (18.4% vs 5.3%), but the differences between the two groups were not statistically significant (P>0.05). Survival curves showed that the patients with higher Galectin-3 expression had significant shorter median OS (P=0.028) and RFS (P=0.001). The cumulative incidence of relapse of high expression group was significantly higher than that of low expression group (P=0.02), but there was no significant difference in cumulative incidence of mortality between the two groups (P=0.209). Meanwhile, the patients were grouped according to the quartiles of serum Galectin-3. The study found that the overexpression or very low expression of Galectin-3 was correlated with poorer prognosis. The study also revealed that CD2 expression was significant associated with reduced CR and with an increased rate of early death. Age was closely correlated with increased early death and relapse rate. The significant unfavorable factors were old age, higher Galectin-3 levels, the presence of CD34 and CD56 expression for 1-year RFS (p<0.05).[Conclusions]High expression of serum Galectin-3 protein in the patients with AML including APL is associated with a variety of clinical and laboratory prognostic indicators. Galectin-3 expression level was significantly different during newly diagnosed, complete remission and relapse stages, suggesting that Galectin-3 may become an indicator of evaluation of curative effect, detection of minimal residual disease, and prediction of recurrence. The patients with higher Galectin-3 expression have poorer response to treatment, shorter survival time, and worse prognosis. Multivariate analysis showed that serum Galectin-3 can be used as independent prognostic indicators in patients with non-M3 AML and APL. The potential of Galectin-3 for evaluating the prognosis of leukemia is great. Serum Galectin-3 may be a reliable prognostic indicator and potential therapeutic targets in patients with acute leukemia.