Xiuqiang Wang

MPL mutation profile in JAK2 mutation-negative patients with myeloproliferative disorders.

Mutations in the thrombopoietin receptor gene (myeloproliferative leukemia, MPL) have been reported in patients with JAK2 V617F-negative chronic myeloproliferative disorders (MPDs). We evaluated the prevalence of MPL mutations relative to JAK2 mutations in patients with suspected MPDs. A total of 2790 patient samples submitted for JAK2 mutation analysis were tested using real-time polymerase chain reaction and bidirectional sequencing of plasma RNA. JAK2 V617F-negative samples were tested for JAK2 exons 12 to 14 mutations, and those with negative results were then tested for mutations in MPL exons 10 and 11. Of the 2790 patients, 529 (18.96%) had V617F, 12 (0.43%) had small insertions or deletions in exon 12, and 7 (0.25%) had other JAK2 mutations in exons 12 to 14. Of the 2242 JAK2 mutation-negative patients, 68 (3.03%) had MPL mutations. W515L was the predominant MPL mutation (n=46; 68%), and 10 (15%) patients had other W515 variants. The remaining MPL mutations (n=12, 17%) were detected at other locations in exons 10 and 11 and included 3 insertion/deletion mutations. The S505N mutation, associated with familial MPD, was detected in 3 patients. Overall, for every 100 V617F mutations in patients with suspected MPDs, there were 12.9 MPL mutations, 2.3 JAK2 exon 12 mutations, and 1.3 JAK2 exons 13 to 14 mutations. These findings suggest that MPL mutation screening should be performed before JAK2 exons 12 to 14 testing in JAK2 V617F-negative patients with suspected MPDs.

Significant association between polymorphism of the erythropoietin gene promoter and myelodysplastic syndrome

BackgroundMyelodysplastic syndrome (MDS) may be induced by certain mutagenic environmental or chemotherapeutic toxins; however, the role of susceptibility genes remains unclear. The G/G genotype of the single-nucleotide polymorphism (SNP) rs1617640 in the erythropoietin (EPO) promoter has been shown to be associated with decreased EPO expression. We examined the association of rs1617640 genotype with MDS.MethodsWe genotyped the EPO rS1617640 SNP in 189 patients with MDS, 257 with acute myeloid leukemia (AML), 106 with acute lymphoblastic leukemia, 97 with chronic lymphocytic leukemia, 353 with chronic myeloid leukemia, and 95 healthy controls.ResultsThe G/G genotype was significantly more common in MDS patients (47/187; 25.1%) than in controls (6/95; 6.3%) or in patients with other leukemias (101/813; 12.4%) (all P < 0.001). Individuals with the G/G genotype were more likely than those with other genotypes to have MDS (odd ratio = 4.98; 95% CI = 2.04-12.13). Clinical and follow up data were available for 112 MDS patients and 186 AML patients. There was no correlation between EPO promoter genotype and response to therapy or overall survival in MDS or AML. In the MDS group, the GG genotype was significantly associated with shorter complete remission duration, as compared with the TT genotype (P = 0.03). Time to neutrophils recovery after therapy was significantly longer in MDS patients with the G/G genotype (P = 0.02).ConclusionsThese findings suggest a strong association between the rs1617640 G/G genotype and MDS. Further studies are warranted to investigate the utility of screening for this marker in individuals exposed to environmental toxins or chemotherapy.

Plasma ubiquitin–proteasome system profile in patients with multiple sclerosis: correlation with clinical features, neuroimaging, and treatment with interferon-beta-1b

Abstract Objective: Interferon-beta-1b (IFN-beta-1b) reduces relapses in multiple sclerosis (MS) and improves magnetic resonance imaging (MRI) outcomes. Mechanism of action of IFN-beta-1b is only marginally understood. The roles and plasma levels of factors within the ubiquitin–proteasome system (UPS) and the plasma proteasome enzymatic activity of MS patients have not been explored. We hypothesized that pharmacologic double inhibition of the UPS by IFN-beta-1b occurs in MS patients and contributes to improvement of clinical course and reduction in MRI activity. Methods: During a 6-month prospective study, we measured plasma proteasome and ubiquitin protein levels and the proteasome enzymatic activities in patients with MS pre- (n = 35) and post-treatment (n = 26) with IFN-beta-1b and 96 normal controls. The results were compared to clinical and brain MRI outcomes. Results: Plasma levels of ubiquitin and proteasome enzymatic activities were elevated in MS patients before therapy with IFN-beta-1b as compared to normals (P<0·01). Additionally, UPS enzymatic activities were increased in MS patients before treatment with IFN-beta-1b (P<0·0001). Six months after treatment with IFN-beta-1b, plasma levels of proteasome and ubiquitin showed further elevation as compared to the pre-treatment values and normals. Treatment with IFN-beta-1b suppressed the enzymatic activity of plasma proteasome and such lowered level of enzymatic activity correlated with a decline in the number of post-contrast T1-weighted enhancing lesions. Conclusion: Since UPS is linked to protein degradation, it may contribute to the course of immune-mediated diseases such as MS, and pharmacologic inhibition of UPS through IFN-beta-1b therapy improves the clinical course of MS. Larger clinical trials are needed to confirm the results of this preliminary study.

Measurement of Cetuximab and Panitumumab-Unbound Serum EGFR Extracellular Domain Using an Assay Based on Slow Off-Rate Modified Aptamer (SOMAmer) Reagents

Background Response to cetuximab (Erbitux®) and panitumumab (Vectibix®) varies among individuals, and even those who show response ultimately gain drug resistance. One possible etiologic factor is differential interaction between the drug and target. We describe the development of an assay based on Slow Off-rate Modified Aptamer (SOMAmer™) reagents that can distinguish drug-bound from unbound epidermal growth factor receptor (EGFR). Methods This quantitative assay uses a SOMAmer reagent specific for EGFR extracellular domain (ECD) as a capturing reagent. Captured SOMAmer is quantitated using PCR. Linearity and accuracy (recovery) of the assay were assessed using normal sera and purified EGFR ECD. Results This EGFR ECD assay showed linearity between 2.5 and 600 ng/mL. Average recovery was 101%. The assay detected EGFR but showed little cross-reactivity to other ErbB proteins: 0.4% for ErbB2, 6.9% for ErbB3, and 1.3% for ErbB4. Preincubation of normal serum with either cetuximab or panitumumab resulted in a dose-dependent decrease in EGFR ECD levels measured using the SOMAmer assay; preincubation did not affect measurement with an ELISA. Conclusions This SOMAmer-based serum EGFR ECD assay accurately and specifically measures EGFR in serum. Detection of significant amounts of drug-unbound EGFR in patients undergoing cetuximab or panitumumab treatment could be an indicator of poor drug response. Further studies are needed to evaluate the utility of the assay as an indicator of drug efficacy or as a guide to dosing.

Three novel alternative splicing mutations in BCR-ABL1 detected in CML patients with resistance to kinase inhibitors

Introduction:  Multiple types of mutations in the BCR‐ABL1 kinase domain have been reported. We previously reported a common alternatively spliced BCR‐ABL mRNA with a 35‐nucleotide insertion (35INS). We report three novel alternative splicing mutants expressed as the dominant transcripts in patient with chronic myelogenous leukemia and resistance to kinase inhibitors.

JAK2 Exon 14 Deletion in Patients with Chronic Myeloproliferative Neoplasms

Background The JAK2 V617F mutation in exon 14 is the most common mutation in chronic myeloproliferative neoplasms (MPNs); deletion of the entire exon 14 is rarely detected. In our previous study of >10,000 samples from patients with suspected MPNs tested for JAK2 mutations by reverse transcription-PCR (RT-PCR) with direct sequencing, complete deletion of exon 14 (Δexon14) constituted <1% of JAK2 mutations. This appears to be an alternative splicing mutation, not detectable with DNA-based testing. Methodology/Principal Findings We investigated the possibility that MPN patients may express the JAK2 Δexon14 at low levels (<15% of total transcript) not routinely detectable by RT-PCR with direct sequencing. Using a sensitive RT-PCR–based fluorescent fragment analysis method to quantify JAK2 Δexon14 mRNA expression relative to wild-type, we tested 61 patients with confirmed MPNs, 183 with suspected MPNs (93 V617F-positive, 90 V617F-negative), and 46 healthy control subjects. The Δexon14 variant was detected in 9 of the 61 (15%) confirmed MPN patients, accounting for 3.96% to 33.85% (mean  = 12.04%) of total JAK2 transcript. This variant was also detected in 51 of the 183 patients with suspected MPNs (27%), including 20 of the 93 (22%) with V617F (mean [range] expression  = 5.41% [2.13%–26.22%]) and 31 of the 90 (34%) without V617F (mean [range] expression  = 3.88% [2.08%–12.22%]). Immunoprecipitation studies demonstrated that patients expressing Δexon14 mRNA expressed a corresponding truncated JAK2 protein. The Δexon14 variant was not detected in the 46 control subjects. Conclusions/Significance These data suggest that expression of the JAK2 Δexon14 splice variant, leading to a truncated JAK2 protein, is common in patients with MPNs. This alternatively spliced transcript appears to be more frequent in MPN patients without V617F mutation, in whom it might contribute to leukemogenesis. This mutation is missed if DNA rather than RNA is used for testing.

Ubiquitin‐proteasome profiling for enhanced detection of hepatocellular carcinoma in patients with chronic liver disease

Background and Aim:  A reliable test for the detection of hepatocellular carcinoma (HCC) could improve disease management. Recent reports suggested a link between abnormalities in the ubiquitin‐proteasome system (UPS) and HCC. We investigated the potential of using UPS markers, along with HCC markers, to differentiate HCC from chronic liver disease (CLD).