Inhibition of DNMT3B and PI3K/AKT/mTOR and ERK Pathways as a Novel Mechanism of Volasertib on Hypomethylating Agent-Resistant Cells.

Resistance to hypomethylating agents (HMAs) in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) is a concerning problem. Polo-like kinase 1 (PLK1) is a key cell cycle modulator and is known to be associated with an activation of the PI3K pathway, which is related to the stabilization of DNA methyltransferase 1 (DNMT1), a target of HMAs. We investigated the effects of volasertib on HMA-resistant cell lines (MOLM/AZA-1 and MOLM/DEC-5) derived from MOLM-13, and bone marrow (BM) samples obtained from patients with MDS (BM blasts >5%) or AML evolved from MDS (MDS/AML). Volasertib effectively inhibited the proliferation of HMA-resistant cells with suppression of DNMTs and PI3K/AKT/mTOR and ERK pathways. Volasertib also showed significant inhibitory effects against primary BM cells from patients with MDS or MDS/AML, and the effects of volasertib inversely correlated with DNMT3B expression. The DNMT3B-overexpressed AML cells showed primary resistance to volasertib treatment. Our data suggest that volasertib has a potential role in overcoming HMA resistance in patients with MDS and MDS/AML by suppressing the expression of DNMT3 enzymes and PI3K/AKT/mTOR and ERK pathways. We also found that DNMT3B overexpression might be associated with resistance to volasertib.

Antileukemic activity of YPN-005, a CDK7 inhibitor, inducing apoptosis through c-MYC and FLT3 suppression in acute myeloid leukemia.

Acute myeloid leukemia (AML) is an aggressive blood cancer with a high rate of relapse associated with adverse survival outcomes, especially in elderly patients. An aberrant expression of cyclin dependent kinase 7 (CDK7) is associated with poor outcomes and CDK7 inhibition has showed antitumor activities in various cancers. We investigated the efficacy of YPN-005, a CDK7 inhibitor in AML cell lines, xenograft mouse model, and primary AML cells. YPN-005 effectively inhibited the proliferation of AML cells by inducing apoptosis and reducing phosphorylation of RNA polymerase II. The c-MYC expression decreased with treatment of YPN-005, and the effect of YPN-005 was negatively correlated with c-MYC expression. YPN-005 also showed antileukemic activities in primary AML cells, especially those harboring FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation and in in vivo mouse model. Phosphorylated FLT3/Signal transducer and activator of transcription 5 (STAT5) was decreased and FLT3/STAT5 was downregulated with YPN-005 treatment. Our data suggest that YPN-005 has a role in treating AML by suppressing c-MYC and FLT3.

Clinical implications and genetic features of clonal cytopenia of undetermined significance compared to lower-risk myelodysplastic syndrome.

Clonal cytopenia of undetermined significance (CCUS) is characterized by persistent cytopenias with genetic aberrations, which do not meet the diagnostic criteria for myelodysplastic syndrome (MDS). We aimed to compare the clinical and genetic characteristics of CCUS with lower-risk MDS and identify patients with CCUS with a high risk of progression. We performed targeted sequencing of bone marrow (BM) samples from patients with idiopathic cytopenia of undetermined significance (ICUS) (n = 139) and MDS (n = 226). Overall survival (OS) of patients with CCUS (n = 78) was worse than non-clonal ICUS (n = 61) and superior to lower-risk MDS (n = 99). Patients with CCUS showed similar characteristics to those with lower-risk MDS, except for higher haemoglobin, lower BM cellularity, and less frequent SF3B1 mutations. Lower haemoglobin, DDX41 (biallelic germline and somatic), ETV6, and RUNX1 mutations were independent prognostic factors for worse OS. Lower haemoglobin and DDX41 mutations were also associated with lower progression-free survival. Patients with CCUS with high-risk features showed similar or worse OS than patients with lower-risk MDS. Our findings suggest that patients with CCUS having certain clinical or genetic features should be regarded and treated as lower-risk MDS despite lacking significant dysplasia or MDS-associated chromosomal abnormalities.

Unique ethnic features of DDX41 mutations in patients with idiopathic cytopenia of undetermined significance, myelodysplastic syndrome, or acute myeloid leukemia.

DDX41 mutations are associated with hematologic malignancies including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but the incidence in idiopathic cytopenia of undetermined significance (ICUS) is unknown. We investigated the incidence, genetic characteristics, and clinical features of DDX41 mutations in Korean patients with ICUS, MDS, or AML. We performed targeted deep sequencing of 61 genes including DDX41 in 457 patients with ICUS (n=75), MDS (n=210), or AML (n=172). Germline DDX41 mutations with causality were identified in 28 (6.1%) patients, of whom 27 (96.4%) had somatic mutations in the other position of DDX41. Germline origins of the DDX41 mutations were confirmed in all of the 11 patients in whom germline-based testing was performed. Of the germline DDX41 mutations, p.V152G (n=10) was most common, followed by p.Y259C (n=8), p.A500fs (n=6), and p.E7* (n=3). Compared with non-mutated patients, patients with a DDX41 mutation were more frequently male, older, had a normal karyotype, low leukocyte count, and hypocellular marrow at diagnosis. Three of the four ICUS patients with germline DDX41 mutations progressed to MDS. The incidence of DDX41 mutations in Korean patients was high and there was a distinct mutation pattern, in that p.V152G was a unique germline variant. ICUS harboring germline DDX41 mutations may be regarded as a hereditary myeloid neoplasm. Germline DDX41 mutations are not uncommon and should be explored when treating patients with myeloid malignancies.

Clinical implications of copy number alteration detection using panel-based next-generation sequencing data in myelodysplastic syndrome.

Recent advancements in next-generation sequencing (NGS) technologies allow the simultaneous identification of targeted copy number alterations (CNAs) as well as somatic mutations using the same panel-based NGS data. We investigated whether CNAs detected by the targeted NGS data provided additional clinical implications, over somatic mutations, in myelodysplastic syndrome (MDS). Targeted deep sequencing of 28 well-known MDS-related genes was performed for 266 patients with MDS. Overall, 215 (80.8 %) patients were found to have at least one somatic mutation; 67 (25.2 %) had at least one CNA; 227 (85.3 %) had either a somatic mutation or CNA; and 12 had CNA without somatic mutations. Considering the clinical variables and somatic mutations alone, multivariate analysis demonstrated that sex, revised International Prognostic Scoring System (IPSS-R), and NRAS and TP53 mutations were independent prognostic factors for overall survival. For AML-free survival, these factors were sex, IPSS-R, and mutations in NRAS, DNMT3A, and complex karyotype/TP53 mutations. When we consider clinical variables along with somatic mutations and CNAs, genetic alterations in TET2, LAMB4, U2AF1, and CBL showed additional significant impact on the survivals. In conclusion, our study suggests that the concurrent detection of somatic mutations and targeted CNAs may provide clinically useful information for the prognosis of MDS patients.

Expression and prognostic significance of microRNAs in Korean patients with myelodysplastic syndrome.

BACKGROUND/AIMS: Various alterations of microRNA (miRNA) expression have been reported in myelodysplastic syndrome (MDS). We aimed to investigate the unique patterns and prognostic significance of miRNA expression in Korean patients with MDS. METHODS: Bone marrow mononuclear cells were collected from eight healthy controls and 26 patients with MDS, and miRNAs were isolated and assessed via quantitative real-time polymerase chain reaction for selected miRNAs, including miR-21, miR-124a, miR-126, miR-146b-5p, miR-155, miR-182, miR-200c, miR-342-5p, miR-708, and Let-7a. RESULTS: MiR-124a, miR-155, miR-182, miR-200c, miR-342-5p, and Let-7a were significantly underexpressed in patients with MDS, compared to healthy controls. MiR-21, miR-126, 146b-5p, and miR-155 transcript levels were significantly lower in international prognostic scoring system lower (low and intermediate-1) risk MDS than in higher (intermediate-2 and high) risk MDS. Higher expression levels of miR-126 and miR-155 correlated with significantly shorter overall survival and leukemia-free survival. Higher miR-124a expression also tended to be related to shorter survivals. CONCLUSION: Although our study was limited by the relatively small number of patients included, we identified several miRNAs associated with pathogenesis, leukemic transformation, and prognosis in MDS.

TP53 mutation in allogeneic hematopoietic cell transplantation for de novo myelodysplastic syndrome.

We investigated the prognostic role of somatic mutations in allogeneic hematopoietic cell transplantation (HCT) for de novo myelodysplastic syndrome (MDS). We performed targeted deep sequencing analysis of 26 genes on bone marrow samples obtained within 6 weeks before HCT from 202 patients with de novo MDS. Overall, 76% of patients carried one or more somatic mutations, and TP53 mutation was present in 23 patients (11.4%). Overall survival (OS) at 5 years was 63.6%, cumulative incidence of relapse (CIR) was 18.6%, event-free survival (EFS) was 58.5%, and non-relapse mortality (NRM) was 22.9%. TP53 mutation was an independent risk factor for lower OS (41% vs. 67%; P = 0.001), higher CIR (49% vs. 15%; P = 0.001), and lower EFS (38% vs. 61%; P = 0.005), but not for NRM (13% vs. 24%). N-RAS mutation was an independent risk factor for higher CIR (HR, 5.91; P = 0.008). TP53 mutation did not have significant interactions with conditioning intensity or the occurrence of graft-versus-host disease with regard to post-transplant outcomes. In conclusion, TP53 mutation was significantly associated with poor outcomes after HCT for patients with de novo MDS, mainly due to a higher incidence of disease relapse.

Comparison of anthracyclines used for induction chemotherapy in patients with FLT3-ITD-mutated acute myeloid leukemia.

This retrospective analysis compared anthracyclines (as part of an induction regimen) in 128 newly diagnosed FLT3-ITD-mutated AML patients. Induction regimens comprised high-dose daunorubicin (HD-DN; 90 mg/m2/d × 3d; n = 44), standard-dose daunorubicin (SD-DN; 45 mg/m2/d × 3d; n = 51), or idarubicin (IDA; 12 mg/m2/d × 3d; n = 33) in combination with cytarabine (100-200 mg/m2/d × 7d). Fifty-three patients showing persistent leukemia on interim bone marrow examination received a second course of induction chemotherapy comprising 2 days of daunorubicin (45 mg/m2/d) or IDA (8 or 12 mg/m2/d) in addition to 5 days of cytarabine. Complete remission (CR) rates were 77.3%, 56.9%, and 69.7% for HD-DN, SD-DN, and IDA, respectively (P = 0.101; HD-DN vs. SD-DN, P = 0.036; HD-DN vs. IDA, P = 0.453; IDA vs. SD-DN, P = 0.237). The HD-DN showed higher overall survival (OS) and event-free survival (EFS) than SD-DN and IDA: the differences between HD-DN and SD-DN (P = 0.009 for OS and P = 0.010 for EFS) were statistically significant. Results of in vitro studies using FLT3-ITD-mutated cell lines supported these findings. In conclusion, HD-DN improved the CR rate, OS, and EFS of FLT3-ITD-mutated AML patients. HD-DN also tended to yield better outcomes than IDA, though the difference was not significant. The superiority of HD-DN over IDA should be confirmed in future studies.

Prospective Randomized Comparison of Idarubicin and High-Dose Daunorubicin in Induction Chemotherapy for Newly Diagnosed Acute Myeloid Leukemia.

Purpose We compared two induction regimens, idarubicin (12 mg/m2/d for 3 days) versus high-dose daunorubicin (90 mg/m2/d for 3 days), in young adults with newly diagnosed acute myeloid leukemia (AML). Patients and Methods A total of 299 patients (149 randomly assigned to cytarabine plus idarubicin [AI] and 150 assigned to cytarabine plus high-dose daunorubicin [AD]) were analyzed. All patients received cytarabine (200 mg/m2/d for 7 days). Results Complete remission (CR) was induced in 232 patients (77.6%), with no difference in CR rates between the AI and AD arms (80.5% v 74.7%, respectively; P = .224). At a median follow-up time of 34.9 months, survival and relapse rates did not differ between the AI and AD arms (4-year overall survival, 51.1% v 54.7%, respectively; P = .756; cumulative incidence of relapse, 35.2% v 25.1%, respectively; P = .194; event-free survival, 45.5% v 50.8%, respectively; P = .772). Toxicity profiles were also similar in the two arms. Interestingly, overall and event-free survival times of patients with FLT3 internal tandem duplication (ITD) mutation were significantly different (AI v AD: median overall survival, 15.5 months v not reached, respectively; P = .030; event-free survival, 11.9 months v not reached, respectively; P = .028). Conclusion This phase III trial comparing idarubicin with high-dose daunorubicin did not find significant differences in CR rates, relapse, and survival. Significant interaction between the treatment arm and the FLT3-ITD mutation was found, and high-dose daunorubicin was more effective than idarubicin in patients with FLT3-ITD mutation.

Induction of immunoglobulin transcription factor 2 and resistance to MEK inhibitor in melanoma cells.

Primary or acquired resistance to MEK inhibitors has been a barrier to successful treatment with MEK inhibitors in many tumors. In this study, we analyzed genome-wide gene expression profiling data from 6 sensitive and 6 resistant cell lines to identify candidate genes whose expression changes are associated with responses to a MEK inhibitor, selumetinib (AZD6244). Of 62 identified differentially expressed genes, we selected Immunoglobulin Transcription Factor 2, also known as transcription factor 4 as a potential drug resistance marker for further analysis. This was because the ITF-2 expression increase in resistant cell lines was relatively high and a previous study has suggested that ITF-2 functions as an oncogene in human colon cancers. We also established an AZD6244 resistant cell line (M14/AZD-3) from an AZD6244 sensitive M14 cell line. The expression of the ITF-2 was elevated both in primary AZD6244 resistant cell line, LOX-IMVI and acquired resistant cell line, M14/AZD-3. Targeted silencing of ITF-2 by siRNA significantly enhanced susceptibility to AZD6244 in resistant cells. Wnt/ß-catenin pathway was activated through direct interaction of p-ERK and GSK3ß. Our results suggest that up-regulation of the ITF-2 gene expression is associated with cellular resistance to MEK inhibitors, and activation of Wnt signaling pathway through interaction of p-ERK and GSK3ß seems to be a mechanism for increase of ITF-2.

Establishment and characterization of hypomethylating agent-resistant cell lines, MOLM/AZA-1 and MOLM/DEC-5.

Two hypomethylating agents (HMAs), azacitidine and decitabine, have demonstrated clinical activities in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML); however, potential problems include development of acquired resistance. HMA-resistant patients have very poor prognosis and this cohort of patients constitutes an important area of research. To understand the mechanisms underlying HMA-resistance and to overcome it, we established an azacitidine-resistant cell line, MOLM/AZA-1 and a decitabine-resistant cell line, MOLM/DEC-5 using MOLM-13. For cytogenetic characterization, we performed microarray-based comparative genomic hybridization (array-CGH), which identified a total of 15 copy number alterations (CNAs). Among these CNAs, eight regions in HMA-resistant cell lines showed CNA patterns distinct from the parental MOLM-13 genome. Single nucleotide polymorphism (SNP) microarray was also performed to obtain a more reliable interpretation of the identified CNAs, and all HMA-resistance-specific CNAs except one detected by array-CGH were successfully validated. In addition to CNAs, copy neutral loss of heterozygosity and mosaic loss events were identified in HMA-resistant cell lines. In our resistant cell lines, MDR-1 was not overexpressed, while DNMT3b was upregulated. Azacitidine and decitabine did not inhibit DNMT1, DNMT3a, or DNMT3b in both HMA-resistant cell lines, while they inhibited the enzymes in parental MOLM-13. We also developed mouse xenograft models using MOLM/AZA-1 and MOLM/DEC-5. Our in vitro and in vivo models of HMA-resistant cell lines will provide clues for the elucidation of molecular mechanisms related to the development of resistance to HMA and tools for the application of novel therapeutics for AML and MDS.

Somatic mutations predict outcomes of hypomethylating therapy in patients with myelodysplastic syndrome.

Although hypomethylating therapy (HMT) is the first line therapy in higher-risk myelodysplastic syndromes (MDS), predicting response to HMT remains an unresolved issue. We aimed to identify mutations associated with response to HMT and survival in MDS. A total of 107 Korean patients with MDS who underwent HMT (57 responders and 50 non-responders) were enrolled. Targeted deep sequencing (median depth of coverage 1,623X) was performed for 26 candidate MDS genes. In multivariate analysis, no mutation was significantly associated with response to HMT, but a lower hemoglobin level (<10g/dL, OR 3.56, 95% CI 1.22-10.33) and low platelet count (<50,000/µL, OR 2.49, 95% CI 1.05-5.93) were independent markers of poor response to HMT. In the subgroup analysis by type of HMT agents, U2AF1 mutation was significantly associated with non-response to azacitidine, which was consistent in multivariate analysis (OR 14.96, 95% CI 1.67-134.18). Regarding overall survival, mutations in DNMT1 (P=0.031), DNMT3A (P=0.006), RAS (P=0.043), and TP53 (P=0.008), and two clinical variables (male-gender, P=0.002; IPSS-R H/VH, P=0.026) were independent predicting factors of poor prognosis. For AML-free survival, mutations in DNMT3A (P<0.001), RAS (P=0.001), and TP53 (P=0.047), and two clinical variables (male-gender, P=0.024; IPSS-R H/VH, P=0.005) were independent predicting factors of poor prognosis. By combining these mutations and clinical predictors, we developed a quantitative scoring model for response to azacitidine, overall- and AML-free survival. Response to azacitidine and survival rates became worse significantly with increasing risk-scores. This scoring model can make prognosis prediction more reliable and clinically applicable.

Single nucleotide polymorphism of Wilms' tumor 1 gene rs16754 in Korean patients with cytogenetically normal acute myeloid leukemia.

A recent study from Germany showed that WT1 single nucleotide polymorphism (SNP) rs16754 was an independent prognostic factor in cytogenetically normal acute myeloid leukemia (CN-AML). We analyzed clinical impact of the WT1 rs16754 genotype on disease characteristics and outcomes in Korean patients with CN-AML. A total of 73 patients with CN-AML were included in the study. All patients received standard induction chemotherapy and their bone marrow or peripheral blood samples were cryopreserved at the time of diagnosis. WT1 exons 7 and 9 were amplified using polymerase chain reaction and directly sequenced. The genotype frequency for WT1 rs16754 was 6.8% for AA, 39.7% for GA, and 53.4% for GG. G was a minor allele in German population, whereas it was a major allele in Korean (13.7% vs. 73.3%, P < 0.001). Complete remission was induced in 85.3% of patients with GA/AA and 84.6% of those with GG (P = 0.936). Survival rates were also similar between patients with GG and those with GA/AA. Asian and Western populations exhibited significant differences in allele and genotype frequencies of WT1 rs16754. In Korean patients with CN-AML, WT1 SNP rs16754 had no significant impact on clinical outcomes and further investigations are needed to define prognostic implication of WT1 SNP rs16754 in CN-AML.

Influence of GST gene polymorphisms on the clearance of intravenous busulfan in adult patients undergoing hematopoietic cell transplantation.

Intravenous (i.v.) busulfan can produce a more consistent pharmacokinetic profile than oral formulations can, but nonetheless, significant interpatient variability is evident. We investigated the influence of polymorphisms of 3 GST isozyme genes (GSTA1, GSTM1, and GSTT1) on i.v. busulfan clearance. Fifty-eight adult patients who received 3.2 mg/kg/day of busulfan as conditioning for hematopoietic cell transplantation were included in this study. Stepwise multiple linear regression demonstrated that GSTA1 variant GSTA1∗B (P = .004), GSTM1/GSTT1 double-null genotype (P = .039), and actual body weight (P = .001) were significantly associated with lower clearance of i.v. busulfan. A trend test analyzing the overall effect of GST genotype on busulfan pharmacokinetics, combining GSTA1 gene polymorphism and the number of GSTM1- and GSTT-null genotypes, showed a significant correlation between GST genotype and busulfan clearance (P = .001). The clearance of i.v. busulfan was similar between patients with GSTA1∗A/∗A and GSTM1/GSTT1 double-null genotypes and those with GSTA1∗A/∗B and GSTM1/GSTT1 double-positive genotypes. In conclusion, a pharmacogenetic approach using GST gene polymorphisms may be valuable in optimizing the i.v. busulfan dosage scheme. Our results also highlight the importance of including polygenic analyses and addressing interactions among isozyme genes in pharmacogenetic studies.

Clinical significance of GSTM1 and GSTT1 polymorphisms in younger patients with acute myeloid leukemia of intermediate-risk cytogenetics.

We investigated the association between GSTM1 or GSTT1 polymorphisms and clinical outcomes in 133 younger patients with AML of intermediate-risk cytogenetics. Clinical outcomes were not significantly different among the GSTM1 polymorphism genotypes, whereas cumulative incidence of relapse (CIR) was significantly lower and event-free survival (EFS) was significantly higher in patients with the GSTT1-present genotype compared with those with the GSTT1-null genotype (CIR at 5 year, 28.9% vs. 44.6%, P=0.018; EFS at 5 year, 51.4% vs. 34.1%, P=0.029). Our results suggest that GSTT1 gene polymorphism has significant clinical implications in younger patients with AML of intermediate-risk cytogenetics.

C3435T polymorphism of the MDR1 gene is not associated with P-glycoprotein function of leukemic blasts and clinical outcome in patients with acute myeloid leukemia.

We investigated the association between the MDR1 C3435T polymorphism and P-glycoprotein function of leukemic blasts as well as clinical outcomes in 200 patients with AML, excluding the M3 subtype. The CC, CT and TT genotype frequencies of the C3435T polymorphism among patients were 71, 93 and 36, respectively. The C3435T polymorphism genotypes did not have influence on the P-glycoprotein function of leukemic blasts. Complete remission rates and overall, relapse-free and event-free survival rates were not significantly different among the C3435T polymorphism genotypes. In conclusion, the MDR1 C3435T polymorphism does not appear to have significant clinical implications in AML.

Randomized comparison of four-times-daily versus once-daily intravenous busulfan in conditioning therapy for hematopoietic cell transplantation.

Sixty patients were randomized to receive intravenous busulfan (iBU) either as 0.8 mg/kg, over 2 hours 4 times a day (BU4 arm) or 3.2 mg/kg, over 3 hours once a day (BU1 arm) in conditioning therapy for hematopoietic cell transplantation. The complete pharmacokinetic parameters for the first busulfan dose were obtained from all patients and were comparable between the 2 arms: for the BU4 and BU1 groups, elimination half-life (mean+/-SD) was 2.75+/-0.22 versus 2.83+/-0.21 hours, estimated daily AUC was 6058.0+/-1091.9 versus 6475.5+/-1099.4 microM.min per day, and clearance was 2.05+/-0.36 versus 1.91+/-0.31 mL/min/kg, respectively. Times to engraftment after transplantation were similar between the 2 arms. No significant differences were evident in the occurrence of acute graft-versus-host disease (aGVHD) and hepatic veno-occlusion disease (VOD). Moreover, other toxicities observed within 100 days after transplantation were not significantly different between the 2 arms. The cumulative incidence of nonrelapse mortality was 20.8% in BU4 arm and 13.3% in BU1 arm. In conclusion, our randomized study demonstrates that the pharmacokinetic profiles and posttransplant complications are similar for once-daily iBU and traditional 4-times-daily iBU.

Functional identification of the pro-apoptotic effector domain in human Sox4.

Recent studies provide evidence that Sox4 is involved in regulating apoptosis as well as tumorigenesis of various human cancers; however, its role in the apoptotic machinery is not fully understood. Here we describe that the central domain containing glycine-rich region in Sox4, named CD, is a pivotal pro-apoptotic domain to induce apoptotic cell death. Deletion of the DNA-binding domain or trans-activation domain in Sox4 did not significantly affect pro-apoptotic activity, whereas transient transfection of the high mobility group box or the serine-rich region abrogated the apoptotic activity. Moreover, overexpression of the CD construct (aa 166-342) revealed the apoptotic activity comparable to that of wild-type Sox4, approximately 60% of cell death. Our data suggest that the apoptotic activity of Sox4 can be dissociated from its transcriptional trans-activation and is mediated through its CD.

Rapid purification and analysis of alpha-synuclein proteins: C-terminal truncation promotes the conversion of alpha-synuclein into a protease-sensitive form in Escherichia coli.

Parkinson's disease (PD) is the most common neurodegenerative movement disorder and is characterized by the loss of dopaminergic neurons and the formation of eosinophilic intracytoplasmic inclusion bodies known as Lewy bodies. Although alpha-synuclein is known to be a pivotal factor implicated in the pathogenesis of PD, its function remains to be elucidated. We used the pGEX expression system to develop a simple and rapid method for purifying alpha-synuclein proteins in suitable forms for biochemical studies of their functions. The wild-type alpha-synuclein protein was overexpressed in Escherichia coli and purified to approx. 80% purity with relatively high yields. We also used this expression system to investigate the expression pattern of the various domains of alpha-synuclein. With the exception of the alpha-synuclein protein that was truncated at amino acid residue 95, all domain constructs of alpha-synuclein were purified at similar levels with relatively high yields. Unexpectedly, removal of amino acid residues 96-140 in the C-terminal acidic region of alpha-synuclein promotes its conversion to a protease-sensitive form during expression and purification in E. coli. Our study suggests a method for generating useful reagents to investigate the molecular mechanism by which alpha-synuclein regulates the pathogenesis of PD.