Preclinical evaluation of WYE-687, a mTOR kinase inhibitor, as a potential anti-acute myeloid leukemia agent.

Mammalian target of rapamycin (mTOR) as a potential drug target for treatment of acute myeloid leukemia (AML). Here, we investigated the potential anti-leukemic activity by WYE-687, a potent mTOR kinase inhibitor. We demonstrated that WYE-687 potently inhibited survival and proliferation of established (HL-60, U937, AML-193 and THP-1 lines) and human AML progenitor cells. Yet, same WYE-687 treatment was non-cytotoxic to the primary peripheral blood mononuclear leukocytes (PBMCs) isolated from healthy donors. WYE-687 induced caspase-dependent apoptotic death in above AML cells/progenitor cells. On the other hand, the pan-caspase inhibitor (Z-VAD-FMK), the caspase-3 specific inhibitor (Z-DEVD-FMK) or the caspase-9 specific inhibitor (z-LEHD-fmk) attenuated WYE-687-induced cytotoxicity. At the molecular level, WYE-687 concurrently inhibited activation of mTORC1 (p70S6K1 and S6 phosphorylations) and mTORC2 (AKT Ser-473 and FoxO1/3a phosphorylations), whiling downregulating mTORC1/2-regulated genes (Bcl-xL and hypoxia-inducible factor 1/2α) in both HL-60/U937 cells and human AML progenitor cells. In vivo, oral administration of WYE-687 potently inhibited U937 leukemic xenograft tumor growth in severe combined immunodeficient (SCID) mice, without causing significant toxicities. In summary, our results demonstrate that targeting mTORC1/2 by WYE-687 leads to potent antitumor activity in preclinical models of AML.

Proteomic Profiling of Iron Overload-Induced Human Hepatic Cells Reveals Activation of TLR2-Mediated Inflammatory Response.

BACKGROUND: Hepatic iron overload is common in patients who have undergone hematopoietic cell transplantation (HCT) and may predispose to peri- and post-HCT toxicity. To better reveal more molecules that might be involved in iron overload-induced liver injury, we utilized proteomics to investigate differentially expressed proteins in iron overload-induced hepatocytes vs. untreated hepatocytes. METHODS AND RESULTS: HH4 hepatocytes were exposed to ferric ammonium citrate (FAC) to establish an in vitro iron overload model. Differentially expressed proteins initiated by the iron overload were studied by two-dimensional liquid chromatography tandem mass spectrometry (2D-LC-MS) analysis. We identified 93 proteins whose quantity statistically significantly changes under excess hepatocyte iron conditions. Gene Ontology (GO) analysis showed that these differentially expressed proteins in HH4 cells are involved in various biological process including endocytosis, response to wounding, di-, trivalent inorganic cation homeostasis, inflammatory response, positive regulation of cytokine production, and etc. Meanwhile, proteomics data revealed protein level of TLR2 and IL6ST significantly increased 7 times and 2.9 times, respectively, in iron overloaded HH4 cells. Our subsequent experiments detected that FAC-treated HH4 cells can activate IL6 expression through TLR2-mediated inflammatory responses via the NF-κB pathway. CONCLUSIONS: In this study, we demonstrated that iron overload induced hepatocytes triggering TLR2-mediated inflammatory response via NF-κB signaling pathway in HH4 cells.

JAK2 V617F, MPL W515L and JAK2 Exon 12 Mutations in Chinese Patients with Primary Myelofibrosis.

OBJECTIVE: JAK2 V617F, MPL W515L and JAK2 exon 12 mutations are novel acquired mutations that induce constitutive cytokine-independent activation of the JAK-STAT pathway in myeloproliferative disorders (MPD). The discovery of these mutations provides novel mechanism for activation of signal transduction in hematopoietic malignancies. This research was to investigate their prevalence in Chinese patients with primary myelofibrosis (PMF). METHODS: We introduced allele-specific PCR (AS-PCR) combined with sequence analysis to simultaneously screen JAK2 V617F, MPL W515L and JAK2 exon 12 mutations in 30 patients with PMF. RESULTS: Fifteen PMF patients (50.0%) carried JAK2 V617F mutation, and only two JAK2 V617F-negative patients (6.7%) harbored MPL W515L mutation. None had JAK2 exon 12 mutations. Furthermore, these three mutations were not detected in 50 healthy controls. CONCLUSION: MPL W515L and JAK2 V617F mutations existed in PMF patients but JAK2 exon 12 mutations not. JAK2 V617F and MPL W515L and mutations might contribute to the primary molecular pathogenesis in patients with PMF.

Bortezomib plus intermediate-dose dexamethasone and thalidomide in elderly untreated patients with multiple myeloma: a Chinese experience.

Bortezomib has proven to be active in patients with multiple myeloma (MM), including elderly patients. The aim of this study was to evaluate the efficacy and toxicity of bortezomib in combination with intermediate-dose dexamethasone (Dex) and thalidomide in untreated MM patients aged > or =65 years in a Chinese single center. In this study, 18 patients were treated with bortezomib at 1.3 mg/m(2) IV on Days 1, 4, 8, and 11 and Dex at 20 mg/day IV on Days 1-4 and 8-11 simultaneously. Thalidomide at dose of 100 mg/day was given everyday. The mean number of cycles of bortezomib treatment was 2.06. Three patients (17%) achieved a complete response (CR), four (22%) a very good partial response (VGPR), and nine (50%) a PR, resulting in an overall response rate of 89%. The median time to response was 22 days (range 14-50 days). The duration of response was significantly longer in patients achieving a CR/VGPR with respect to those achieving only a PR (8.5 vs. 4.2 months, P = 0.03). Grade 3-4 toxicities occurring in patients comprised weakness, thrombocytopenia, diarrhea, infection, and neuropathy. Only one patient suffered from deep vein thrombosis. This preliminary experience in Chinese patients indicated that bortezomib-Dex-thalidomide is highly effective in elderly untreated patients with MM, even in patients with poor prognostic features.

[Correlations of JAK2V617F point mutation with clinical and laboratory features in patients with polycythemia vera].

To evaluate JAK2V617F point mutation in patients with polycythemia vera (PV) and its clinical significance, the point mutation was detected by allele specific polymerase chain reaction (AS-PCR), and the clinical and laboratory features of 50 PV patients with JAK2V617F positive and negative mutations were analyzed and compared each other. The results showed that among 50 patients, 31 patients (62.0%) had JAK2V617F point mutation; 12 patients (24.0%) showed thrombosis and microvascular disturbances; 3 patients had chromosome karyotype abnormalities. As compared with negative mutation group, the age and leukocyte count in patients with JAK2V617F point mutation were older (57.5 +/- 10.0 vs 45.6 +/- 14.9, p < 0.05) and higher (16.2 +/- 6.7 vs 9.0 +/- 5.2, p < 0.05) respectively. It is concluded that the frequency of the JAK2V617F point mutation is 62.0% in PV patients, the age and leukocyte count of patients with JAK2V617F point mutation are older and higher respectively than those in negative mutation group.