Methionine-induced hyperhomocysteinemia reverts fibrinolytic pathway activation in a murine model of acute promyelocytic leukemia

Abstract

Increased fibrinolysis is an important component of acute promyelocytic leukemia (APL) bleeding diathesis. APL blasts overexpress annexin II (ANXII), a receptor for tissue plasminogen activator (tPA), and plasminogen, thereby increasing plasmin generation. Previous studies suggested that ANXII plays a pivotal role in APL coagulopathy. ANXII binding to tPA can be inhibited by homocysteine and hyperhomocysteinemia can be induced by L-methionine supplementation. In the present study, we used an APL mouse model to study ANXII function and the effects of hyperhomocysteinemia in vivo. Leukemic cells expressed higher ANXII and tPA plasma levels (11.95 ng/mL in leukemic vs 10.74 ng/mL in wild-type; P ‫؍‬ .004). In leukemic mice, administration of L-methionine significantly increased homocysteine levels (49.0 mol/mL and < 6.0 mol/mL in the treated and nontreated groups, respectively) and reduced tPA levels to baseline concentrations. The latter were also decreased after infusion of the LCKLSL peptide, a competitor for the ANXII tPA-binding site (11.07 ng/mL; P ‫؍‬ .001). We also expressed and purified the p36 component of ANXII in Pichia methanolica. The infusion of p36 in wild-type mice increased tPA and thrombin-antithrombin levels, and IntroductionHemorrhage is the main complication of acute promyelocytic leukemia (APL), and approximately 60%-80% of patients present with a coagulation abnormality at diagnosis. [1][2][3] Despite the improvement in APL treatment outcome, early mortality due to bleeding is still prevalent. 4 At least 3 components contribute to bleeding due to APL: activation of coagulation, proteolysis, and fibrinolysis. APL blasts express both tissue factor and cancer procoagulant and secrete IL-1␤ and TNF␣, 5-7 which leads to excessive fibrin production. Concomitantly, there is proteolytic activity with the generation of D-like fibrin fragments that have an anticoagulant effect. 8 Several elements contribute to fibrinolysis in APL. Reduced levels of plasminogen activator inhibitor 1 (PAI1) 9 and alpha 2 -antiplasmin 10 are observed in the plasma, and thrombinactivatable fibrinolysis inhibitor activity is markedly below normal. 11 Furthermore, urokinase plasminogen activator protein levels are higher in both plasma and leukemic cells. 12,13 Using an in vitro assay, Menell et al demonstrated that the APL cell lineage NB4 can up-regulate plasmin synthesis by approximately 28-fold in a medium containing plasminogen and tissue plasminogen activator (tPA). 14 Annexin II (ANXII) is thought to play a critical role in APL-associated fibrinolysis. It is a phosphatidylinositol-4,5-bisphosphate-binding protein that is overexpressed in APL cells. [14][15][16] ANXII is a receptor for both tPA and plasminogen and in patients with APL, it increases plasmin generation approximately 60-fold and therefore may participate in the pathogenesis of APL bleeding diathesis. 17 Homocysteine competes with tPA for the same site of ANXII through its motif LCKLSL. 18 We hypothesized that by inhibiting ANXII activity through the ind...

Evaluation of D-dimer and lactate dehydrogenase plasma levels in patients with relapsed acute leukemia

“…Activation of coagulation and secondary activation of fibrinolysis are likely to occur continuously and simultaneously throughout circulation (20,24,34). The activation of coagulation is most likely associated with the leukemic cells circulating in the blood, which may contain procoagulants, and the content of these substances depends on the leukemia subtype (35,36). These substances may be released into the blood from disintegrating cells during relapse.…”

Annexin A2 System in Human Biology: Cell Surface and Beyond

“…78 Interestingly, induction of diet-induced hyperhomocysteinemia in a mouse model of APL (hCG-PML-RARα mice) reversed hyperfibrinolysis, thus reinforcing the relevance of A2 to APL in vivo and suggesting a potentially novel therapeutic approach to APL. 82…”

Prognostic impact of KMT2E transcript levels on outcome of patients with acute promyelocytic leukaemia treated with all‐trans retinoic acid and anthracycline‐based chemotherapy: an International Consortium on Acute Promyelocytic Leukaemia study

“…Only prothrombin time, activated partial thromboplastin time and fibrinogen levels were routinely evaluated in the protocol and no significant difference was detected between patients with low and high KMT2E transcript levels. This is not surprising, considering the complexity of pathogenesis of coagulopathy associated with APL (Kwaan & Rego, ; Jacomo et al , ). The fact that only Brazilian patients with APL were analysed here did not represent a bias because no significant difference in treatment outcome was detected among the four participating countries (Rego et al , ).…”