Edward Laane

Cell death induced by dexamethasone in lymphoid leukemia is mediated through initiation of autophagy

Glucocorticoids are fundamental drugs used in the treatment of lymphoid malignancies with apoptotic cell death as the hitherto proposed mechanism of action. Recent studies, however, showed that an alternative mode of cell death, autophagy, is involved in the response to anticancer drugs. The specific role of autophagy and its relationship to apoptosis remains, nevertheless, controversial: it can either lead to cell survival or can function in cell death. We show that dexamethasone induced autophagy upstream of apoptosis in acute lymphoblastic leukemia cells. Inhibition of autophagy by siRNA-mediated repression of Beclin 1 expression inhibited apoptosis showing an important role of autophagy in dexamethasone-induced cell death. Dexamethasone treatment caused an upregulation of promyelocytic leukemia protein, PML, its complex formation with protein kinase B or Akt and a PML-dependent Akt dephosphorylation. Initiation of autophagy and the onset of apoptosis were both dependent on these events. PML knockout thymocytes were resistant to dexamethasone-induced death and upregulation of PML correlated with the ability of dexamethasone to kill primary leukemic cells. Our data reveal key mechanisms of dexamethasone-induced cell death that may inform the development of improved treatment protocols for lymphoid malignancies.

Bortezomib consolidation after autologous stem cell transplantation in multiple myeloma: a Nordic Myeloma Study Group randomized phase 3 trial

The Nordic Myeloma Study Group conducted an open randomized trial to compare bortezomib as consolidation therapy given after high-dose therapy and autologous stem cell transplantation (ASCT) with no consolidation in bortezomib-naive patients with newly diagnosed multiple myeloma. Overall, 370 patients were centrally randomly assigned 3 months after ASCT to receive 20 doses of bortezomib given during 21 weeks or no consolidation. The hypothesis was that consolidation therapy would prolong progression-free survival (PFS). The PFS after randomization was 27 months for the bortezomib group compared with 20 months for the control group (P = .05). Fifty-one of 90 patients in the treatment group compared with 32 of 90 controls improved their response after randomization (P = .007). No difference in overall survival was seen. Fatigue was reported more commonly by the bortezomib-treated patients in self-reported quality-of-life (QOL) questionnaires, whereas no other major differences in QOL were recorded between the groups. Consolidation therapy seemed to be beneficial for patients not achieving at least a very good partial response (VGPR) but not for patients in the ≥ VGPR category at randomization. Consolidation with bortezomib after ASCT in bortezomib-naive patients improves PFS without interfering with QOL. This trial was registered at www.clinicaltrials.gov as #NCT00417911.

Autophagy as the main means of cytotoxicity by glucocorticoids in hematological malignancies.

Glucocorticoids are fundamental drugs used in the treatment of lymphoid malignancies with apoptotic cell death as the hitherto proposed mechanism of action. We have recently shown that dexamethasone induces autophagy in lymphoid leukemia cells and in this particular setting this cell death modality is a prerequisite for the efficient killing of the leukemic cells by dexamethasone.1 Hence, inhibition of autophagy by siRNA-mediated silencing of Beclin 1, as well as chemical inhibition of type III PtdIns3K, inhibits apoptosis, demonstrating an important role of autophagy in dexamethasone-induced cell death. In this brief report, we review these findings and introduce the Multiple Myeloma cells as a novel system to study autophagy in response to dexamethasone.

Dexamethasone-induced apoptosis in acute lymphoblastic leukemia involves differential regulation of Bcl-2 family members

Background and Objectives The mechanism of glucocorticoid -induced apoptosis is not fully understood and early predictive assays based on apoptotic markers for clinical outcome in acute lymphoblastic leukemia (ALL) are scarce. The aim of this study was to characterize the involvement of Bcl-2 family members and caspase activation in dexamethasone(Dex)-induced apoptosis in ALL. Design and Methods Primary childhood ALL samples, the pre-B ALL cell line RS(4;11), and the T-ALL cell line CCRF-CEM were used. The involvement of Bcl-2 family members was evaluated by flow cytometry, immunocytochemistry, and western and northern blotting. Apoptosis was analyzed by annexin V and TMRE staining. Caspase activity was evaluated by a fluorometric assay. Results Dex induced significant down-regulation of the anti-apoptotic Bcl-2 family members Bcl-2 and Bcl-xL, differential activation of the pro-apoptotic Bak and Bax, loss of Δψm and cytochrome c release. Dex-induced apoptosis also involved early activation of caspases 2 and -3. Inhibition of caspase activity did not, however, protect against Dex-induced Bak/Bax activation, loss of Δψm or cell death. In 12 primary ALL samples Dex-induced apoptosis was associated with activation of Bax (p=0.045) and down-regulation of Bcl-2 (p=0.016) and/or Bcl-xL (p=0.004). Furthermore, ex vivo Dex-sensitivity was associated with an early treatment response to polychemotherapy (p=0.026). Interpretation and Conclusions The differential regulation of pro- and anti-apoptotic Bcl-2 family members appears to be a key event in the execution of Dex-induced apoptosis in ALL cell lines, and also indicates a role for these proteins in primary ALL cells.

Sorafenib Has Potent Antitumor Activity against Multiple Myeloma In Vitro, Ex Vivo, and In Vivo in the 5T33MM Mouse Model

Multiple myeloma (MM) is a B-cell malignancy characterized by the expansion of clonal plasma blasts/plasma cells within the bone marrow that relies on multiple signaling cascades, including tyrosine kinase activated pathways, to proliferate and evade cell death. Despite emerging new treatment strategies, multiple myeloma remains at present incurable. Thus, novel approaches targeting several signaling cascades by using the multi-tyrosine kinase inhibitor (TKI), sorafenib, seem a promising treatment approach for multiple myeloma. Here, we show that sorafenib induces cell death in multiple myeloma cell lines and in CD138(+)-enriched primary multiple myeloma patient samples in a caspase-dependent and -independent manner. Furthermore, sorafenib has a strong antitumoral and -angiogenic activity in the 5T33MM mouse model leading to increased overall survival. Multiple myeloma cells undergo autophagy in response to sorafenib, and inhibition of this cytoprotective pathway potentiated the efficacy of this TKI. Mcl-1, a survival factor in multiple myeloma, is downregulated at the protein level by sorafenib allowing for the execution of cell death, as ectopic overexpression of this protein protects multiple myeloma cells. Concomitant targeting of Mcl-1 by sorafenib and of Bcl-2/Bcl-xL by the antagonist ABT737 improves the efficacy of sorafenib in multiple myeloma cell lines and CD138(+)-enriched primary cells in the presence of bone marrow stromal cells. Altogether, our data support the use of sorafenib as a novel therapeutic modality against human multiple myeloma, and its efficacy may be potentiated in combination with ABT737.

Glucocorticoid-induced cell death is mediated through reduced glucose metabolism in lymphoid leukemia cells

Malignant cells are known to have increased glucose uptake and accelerated glucose metabolism. Using liquid chromatography and mass spectrometry, we found that treatment of acute lymphoblastic leukemia (ALL) cells with the glucocorticoid (GC) dexamethasone (Dex) resulted in profound inhibition of glycolysis. We thus demonstrate that Dex reduced glucose consumption, glucose utilization and glucose uptake by leukemic cells. Furthermore, Dex treatment decreased the levels of the plasma membrane-associated glucose transporter GLUT1, thus revealing the mechanism for the inhibition of glucose uptake. Inhibition of glucose uptake correlated with induction of cell death in ALL cell lines and in leukemic blasts from ALL patients cultured ex vivo. Addition of di-methyl succinate could partially overcome cell death induced by Dex in RS4;11 cells, thereby further supporting the notion that inhibition of glycolysis contributes to the induction of apoptosis. Finally, Dex killed RS4;11 cells significantly more efficiently when cultured in lower glucose concentrations suggesting that modulation of glucose levels might influence the effectiveness of GC treatment in ALL. In summary, our data show that GC treatment blocks glucose uptake by leukemic cells leading to inhibition of glycolysis and that these effects play an important role in the induction of cell death by these drugs.

Investigation and management of IgM and Waldenström‐associated peripheral neuropathies: recommendations from the IWWM‐8 consensus panel

Paraproteinaemic neuropathies are a heterogeneous group of disorders most frequently associated with IgM monoclonal gammopathies including Waldenström macroglobulinaemia (WM). Their consequences are significant for affected patients, and their management challenging for their physicians. The variability in clinical presentation and time course hamper classification and management. The indications for invasive investigations such as cerebrospinal fluid analysis, nerve conduction tests and sensory nerve biopsies are unclear, and the optimum way to measure clinical response to treatment unknown. When to intervene and and how to treat, also present challenges to physicians. As part of its latest deliberations at the International Workshops on WM (IWWM) in London, UK (August 2014), the IWWM8 panel have proposed a consensus approach to the diagnosis and management of peripheral neuropathies associated with IgM monoclonal gammopathies, including WM. Importantly, a consensus regarding the use of clinical outcome measures and recommended models of care for this group of patients is discussed, as well as appropriate treatment interventions.

Acute de novo Leukemia in Estonia and Western Sweden 1982-2006: Positive Trend in the Survival of Acute Leukemia over 25 Years

This study focuses on the incidence, treatment, and survival of de novo acute leukemia in a 25-year perspective in western Sweden and Estonia. At the beginning of our study, Estonia was a part of the Eastern bloc with planned economy, but since 1991 it is a member of the European Union and transforming into a market economy. Survival rates have steadily increased in both countries. However, a gap between their survival curves remains. Based on our data, it is difficult to explain the big difference in the 5-year relative survival in favor of western Sweden (55 vs. 22%). In Germany, there was a big difference in overall cancer survival between East and West Germany after the fall of the iron curtain, but today no difference is seen. Differences in survival are probably due to a higher proportion of intense chemotherapy regimens and a higher rate of hematopoietic stem cell transplantations in Sweden. Other important factors might be better supportive care and diagnostics as well as better adjuvant therapy. Better staff training and conditions in wards are also factors that might play an essential role.