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1.  Tanespimycin with bortezomib: activity in relapsed/refractory patients with multiple myeloma 
British journal of haematology  2010;150(4):428-437.
Summary
Tanespimycin (17-allylamino-17-demethoxygeldanamycin, 17-AAG) disrupts heat shock protein 90 (HSP90), a key molecular chaperone for signal transduction proteins critical to myeloma growth, survival and drug resistance. In previous studies, tanespimycin monotherapy was well tolerated and active in heavily pretreated patients with relapsed/refractory multiple myeloma (MM). Preclinical data have shown antitumour synergy between tanespimycin and bortezomib, with more pronounced intracellular accumulation of ubiquitinated proteins than either drug alone, an effect attributed to the synergistic suppression of chymotryptic activity in the 20S proteasome. HSP70 induction has been observed in all Phase 1 tanespimycin studies in which it has been measured, with several separate reports of HSP70 overexpression protecting against peripheral nerve injury. In this Phase 2, open-label multicentre study, we compared 1·3 mg/m2 bortezomib + three doses of tanespimycin: 50, 175 and 340 mg/m2 in heavily pretreated patients with relapsed and refractory MM and measured HSP70 expression and proteasome activity levels in plasma of treated patients. The study was closed prematurely for resource-based reasons, precluding dose comparison. Nonetheless, antitumour activity was observed, with promising response rates and promising severity of peripheral neuropathy.
doi:10.1111/j.1365-2141.2010.08264.x
PMCID: PMC3418598  PMID: 20618338
tanespimycin; bortezomib; HSP90; HSP70; peripheral neuropathy
2.  Effects of Clinically Relevant MPL Mutations in the Transmembrane Domain Revealed at the Atomic Level through Computational Modeling 
PLoS ONE  2011;6(8):e23396.
Background
Mutations in the thrombopoietin receptor (MPL) may activate relevant pathways and lead to chronic myeloproliferative neoplasms (MPNs). The mechanisms of MPL activation remain elusive because of a lack of experimental structures. Modern computational biology techniques were utilized to explore the mechanisms of MPL protein activation due to various mutations.
Results
Transmembrane (TM) domain predictions, homology modeling, ab initio protein structure prediction, and molecular dynamics (MD) simulations were used to build structural dynamic models of wild-type and four clinically observed mutants of MPL. The simulation results suggest that S505 and W515 are important in keeping the TM domain in its correct position within the membrane. Mutations at either of these two positions cause movement of the TM domain, altering the conformation of the nearby intracellular domain in unexpected ways, and may cause the unwanted constitutive activation of MPL's kinase partner, JAK2.
Conclusions
Our findings represent the first full-scale molecular dynamics simulations of the wild-type and clinically observed mutants of the MPL protein, a critical element of the MPL-JAK2-STAT signaling pathway. In contrast to usual explanations for the activation mechanism that are based on the relative translational movement between rigid domains of MPL, our results suggest that mutations within the TM region could result in conformational changes including tilt and rotation (azimuthal) angles along the membrane axis. Such changes may significantly alter the conformation of the adjacent and intrinsically flexible intracellular domain. Hence, caution should be exercised when interpreting experimental evidence based on rigid models of cytokine receptors or similar systems.
doi:10.1371/journal.pone.0023396
PMCID: PMC3157383  PMID: 21858098
3.  Tanespimycin monotherapy in relapsed multiple myeloma: results of a phase 1 dose-escalation study 
British journal of haematology  2010;150(4):438-445.
Summary
Tanespimycin, a heat shock protein 90 (HSP90) inhibitor, induces apoptosis in drug-sensitive and -resistant MM cell lines and in tumour cells from patients with relapsed MM. In this phase 1 dose-escalation study, the safety, plasma pharmacokinetics, and biological/antitumour activity of tanespimycin were evaluated in heavily pretreated patients with relapsed/refractory MM. Tanespimycin (150–525 mg/m2) was given on days 1, 4, 8, and 11 of each 3-week cycle for up to 8 cycles. Non-haematological AEs included diarrhoea (59%), back pain (35%), fatigue (38%), and nausea (35%); haematological AEs included anaemia (24%) and thrombocytopenia (21%). One patient (3%) achieved minimal response (MR), with a progression-free survival (PFS) of 3 months, a 41% decrease from baseline in urine M protein, and a 33% decrease from baseline in serum M protein. Fifteen patients (52%) achieved SD with a median PFS of 2·1 months; 5/15 had reductions in serum M protein ranging from 7% to 38% and in urine M protein ranging from 6% to 91%. Mean HSP70 levels increased from day 1 h 0 to day 1 h 4 with further increases on day 11 h 0 and day 11 h 4, consistent with a therapeutic treatment effect. Tanespimycin monotherapy was well tolerated and demonstrated activity across all doses tested.
doi:10.1111/j.1365-2141.2010.08265.x
PMCID: PMC3126095  PMID: 20618337
Multiple myeloma; tanespimycin; HSP90; HSP70; 17-AAG
4.  Significant association between polymorphism of the erythropoietin gene promoter and myelodysplastic syndrome 
BMC Medical Genetics  2010;11:163.
Background
Myelodysplastic 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.
Methods
We 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.
Results
The 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).
Conclusions
These 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.
doi:10.1186/1471-2350-11-163
PMCID: PMC2992491  PMID: 21078205
5.  JAK2 Exon 14 Deletion in Patients with Chronic Myeloproliferative Neoplasms 
PLoS ONE  2010;5(8):e12165.
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.
doi:10.1371/journal.pone.0012165
PMCID: PMC2921382  PMID: 20730051
6.  Structural effects of clinically observed mutations in JAK2 exons 13-15: comparison with V617F and exon 12 mutations 
Background
The functional relevance of many of the recently detected JAK2 mutations, except V617F and exon 12 mutants, in patients with chronic myeloproliferative neoplasia (MPN) has been significantly overlooked. To explore atomic-level explanations of the possible mutational effects from those overlooked mutants, we performed a set of molecular dynamics simulations on clinically observed mutants, including newly discovered mutations (K539L, R564L, L579F, H587N, S591L, H606Q, V617I, V617F, C618R, L624P, whole exon 14-deletion) and control mutants (V617C, V617Y, K603Q/N667K).
Results
Simulation results are consistent with all currently available clinical/experimental evidence. The simulation-derived putative interface, not possibly obtained from static models, between the kinase (JH1) and pseudokinase (JH2) domains of JAK2 provides a platform able to explain the mutational effect for all mutants, including presumably benign control mutants, at the atomic level.
Conclusion
The results and analysis provide structural bases for mutational mechanisms of JAK2, may advance the understanding of JAK2 auto-regulation, and have the potential to lead to therapeutic approaches. Together with recent mutation profiling results demonstrating the breadth of clinically observed JAK2 mutations, our findings suggest that molecular testing/diagnostics of JAK2 should extend beyond V617F and exon 12 mutations, and perhaps should encompass most of the pseudo-kinase domain-coding region.
doi:10.1186/1472-6807-9-58
PMCID: PMC2749040  PMID: 19744331

Results 1-7 (7)