Should MAGE be the rage in myeloma?

Comparative genetics of warfarin resistance

Warfarin and other 4-hydroxycoumarin-based oral anticoagulants targeting vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) are administered to humans, mice and rats with different purposes in mind - to act as pesticides in high-dosage baits for killing rodents, but also to save lives when administered in low dosages as antithrombotic drugs in humans. However, high-dosage warfarin used to control rodent populations has resulted in numerous mutations causing warfarin resistance. Currently, six single missense mutations in mice, 12 distinct missense mutations in rats, as well as compound heterozygous or homozygous mutations with up to six distinct missense mutations per Vkorc1 allele have been described. Warfarin resistance missense mutations for human VKORC1 have also been found world-wide, but differ characteristically from those in rodents. In humans, 26 distinct mutations have been characterized, but occur only rarely either in heterozygous or, even rarer, in homozygous form. In this review, we summarize the known VKORC1 missense mutations causing warfarin and other 4-hydroxycoumarin drug resistance, identify genomics databases as new sources of data, explore possible underlying genetic mechanisms, and summarize similarities and differences between warfarin resistant VKORC1 variants in humans and rodents.

Diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is one of the most common subtypes of non-Hodgkin lymphoma. It is a heterogeneous disease, and a distinctive subgroup of patients with different treatment outcome can be identified based on clinical and molecular prognostic factors. Cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy has been the standard systemic therapy for this disease with a cure rate of 40% to 50%, although, more recently, the addition of rituximab has been shown in phase III trials to confer a significant survival benefit in both older and younger patients. To further improve on the treatment outcome of this disease, dose-dense, and/or dose-intense regimens have been developed and tested against CHOP. However, these regimens are not yet accepted as standard therapy because of the increased toxicity as well as the uncertain benefit over CHOP with rituximab. In patients with localized DLBCL, available randomized trials suggest that radiation therapy improves local control and disease-free survival and that the addition of radiation therapy cannot replace inadequate chemotherapy.

Management of cold haemolytic syndrome

Most haemolytic disease is mediated by immunoglobulin G (IgG) antibodies and leads to red blood cell destruction outside of the circulatory system. However, rare syndromes, such as paroxysmal cold haemoglobinuria, show IgG antibodies causing intravascular destruction. Haemolysis may also occur because of immunoglobulin M antibodies. Historically, these antibodies have been termed 'cold agglutinins' because they cause agglutination of red blood cells at 3 degrees C. Cold agglutinin haemolytic anaemia has been associated with a number of autoimmune and lymphoproliferative disorders, and its management differs substantially from warm antibody-mediated haemolytic anaemia. This review of cold haemolytic syndromes describes new therapies and clinical strategies to determine a correct diagnosis.

Select cancer testes antigens of the MAGE-A, -B, and -C families are expressed in mast cell lines and promote cell viability in vitro and in vivo

MAGE antigens are proteins that are normally expressed only in gametes but are often aberrantly expressed in melanomas, hematopoietic malignancies, and other "cancers". The functions of most MAGE proteins are unknown. Data have accumulated suggesting expression of MAGE proteins by malignant cells may contribute to advanced disease or resistance to chemotherapy, but direct evidence supporting this hypothesis is lacking. We show here that small interfering RNA (siRNA) suppression of MAGE-A, -B, and -C gene expression slows proliferation and induces caspase independent apoptosis in human and murine mast cell lines. Furthermore, treatment with MAGE specific siRNA suppresses growth of malignant cells in an in vivo murine model of mastocytosis. These observations demonstrate that MAGE protein expression can contribute to the development of tumors by permitting proliferation and prolonging the survival of malignant cells. We suggest a shift of the current clinical paradigm from one that envisions MAGE proteins solely as targets for immunologic attack to one in which MAGE genes and proteins are also targets for functional manipulation.

Insights into abnormal hemostasis in the Quebec platelet disorder from analyses of clot lysis

BACKGROUND

The Quebec platelet disorder (QPD) is inherited and characterized by delayed-onset bleeding following hemostatic challenge. Other characteristics include increased expression and storage of active urokinase-type plasminogen activator (u-PA) in platelets in the setting of normal to increased u-PA in plasma. There is also consumption of platelet plasminogen activator inhibitor-1 and increased generation of plasmin in platelets accompanied by proteolysis of stored alpha-granule proteins, including Factor V.

AIMS AND METHODS

Although fibrinolysis has been proposed to contribute to QPD bleeding, the effects of QPD blood and platelets on clot lysis have not been evaluated. We used thromboelastography (TEG), biochemical evaluations of whole blood clot lysis, assessments of clot ultrastructure, and perfusion of blood over preformed fibrin to gain insights into the disturbed hemostasis in the QPD.

RESULTS

Thromboelastography was not sensitive to the increased u-PA in QPD blood. However, there was abnormal plasmin generation in QPD whole blood clots, generated at low shear, with biochemical evidence of increased fibrinolysis. The incorporation of QPD platelets into a forming clot led to progressive disruption of fibrin and platelet aggregates unless drugs were added to inhibit plasmin. In whole blood perfusion studies, QPD platelets showed normal adherence to fibrin, but their adhesion was followed by accelerated fibrinolysis.

CONCLUSIONS

The QPD is associated with "gain-of-function" abnormalities that increase the lysis of forming or preformed clots. These findings suggest accelerated fibrinolysis is an important contributor to QPD bleeding.