Action Mechanism of Metformin and Its Application in Hematological Malignancy Treatments: A Review.

Hematologic malignancies (HMs) mainly include acute and chronic leukemia, lymphoma, myeloma and other heterogeneous tumors that seriously threaten human life and health. The common effective treatments are radiotherapy, chemotherapy and hematopoietic stem cell transplantation (HSCT), which have limited options and are prone to tumor recurrence and (or) drug resistance. Metformin is the first-line drug for the treatment of type 2 diabetes (T2DM). Recently, studies identified the potential anti-cancer ability of metformin in both T2DM patients and patients that are non-diabetic. The latest epidemiological and preclinical studies suggested a potential benefit of metformin in the prevention and treatment of patients with HM. The mechanism may involve the activation of the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway by metformin as well as other AMPK-independent pathways to exert anti-cancer properties. In addition, combining current conventional anti-cancer drugs with metformin may improve the efficacy and reduce adverse drug reactions. Therefore, metformin can also be used as an adjuvant therapeutic agent for HM. This paper highlights the anti-hyperglycemic effects and potential anti-cancer effects of metformin, and also compiles the in vitro and clinical trials of metformin as an anti-cancer and chemosensitizing agent for the treatment of HM. The need for future research on the use of metformin in the treatment of HM is indicated.

Mucosal-associated invariant T cells predict increased acute graft-versus-host-disease incidence in patients receiving allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Mucosal-associated invariant T (MAIT) cells are innate-like T cells, some studies have reported that the number of circulating MAIT cells reduced in patients with acute graft-versus-host-disease (aGVHD) development. However, the role of donor MAIT cells on aGVHD development and subsequent functional change still remain unclear. METHODS: The study recruited 86 patients with hematological malignancies who underwent allogeneic hematopoietic cell transplantation (HCT) from May 1, 2018 to June 30, 2019. MAIT cells, their subset, and cytokine levels were measured by flow cytometry. Gray's test was used to assess the impact of graft MAIT cell proportion and number on aGVHD incidence. The Cox proportional hazard model was used in the multivariate analysis. The comparison for continuous variables was assessed using Mann-Whitney analysis. RNA-sequencing was performed to investigate the possible molecular pathway changes. RESULTS: Our study showed that the proportion of MAIT cells in grafts was not different from normal controls, but the CD4/8 subsets were altered. Taking the median of the proportion and number of MAIT cells in the graft as the threshold, the results showed that the incidence of grade B-D aGVHD in patients with MAIT cell proportion ≥ 3.03% was significantly higher than that in patients with MAIT cell proportion < 3.03% (56.3%, 95% CI 37.1-71.2 versus 23.1%, 95% CI 13.8-46.2; P = 0.038).The number of MAIT cells in the graft was not associated with aGVHD development (P = 0.173), however, when the graft contained more CD4 positive, CD8 positive, and CD4/CD8 double-positive MAIT cells, the incidence of aGVHD was significantly increased (P = 0.019, P = 0.035 and P = 0.027, respectively). Besides, reduced frequencies and counts of circulating MAIT cells were observed in patients with aGVHD when compared to patients without aGVHD, accompanied by enhanced production of Tumor necrosis factor-α, Interferon-γ and upregulated programmed death-1, CXC Chemokine Receptor-6 (CXCR6) and CD38 expression. Gene set enrichment analysis of MAIT cell RNA-seq data showed interferon-α response pathway upregulated in aGVHD patients when compared with patients without aGVHD and healthy controls. CONCLUSIONS: Our study shows that MAIT cells in grafts and peripheral blood are both closely related to the aGVHD development post allogeneic HCT. Interferon-α response pathway perhaps is a critical regulation mechanism for the MAIT cell involvement in aGVHD development.

ALKBH5-Mediated m6A Demethylation of GLUT4 mRNA Promotes Glycolysis and Resistance to HER2-Targeted Therapy in Breast Cancer.

Resistance to HER2-targeted therapy represents a significant challenge for the successful treatment of patients with breast cancer with HER2-positive tumors. Through a global mass spectrometry-based proteomics approach, we discovered that the expression of the N6-methyladenosine (m6A) demethylase ALKBH5 was significantly upregulated in HER2-targeted therapy-resistant breast cancer cells. Elevated expression of ALKBH5 was sufficient to confer resistance to HER2-targeted therapy, and specific knockdown of ALKBH5 rescued the efficacy of trastuzumab and lapatinib in resistant breast cancer cells. Mechanistically, ALKBH5 promoted m6A demethylation of GLUT4 mRNA and increased GLUT4 mRNA stability in a YTHDF2-dependent manner, resulting in enhanced glycolysis in resistant breast cancer cells. In breast cancer tissues obtained from patients with poor response to HER2-targeted therapy, increased expression of ALKBH5 or GLUT4 was observed and was significantly associated with poor prognosis in the patients. Moreover, suppression of GLUT4 via genetic knockdown or pharmacologic targeting with a specific inhibitor profoundly restored the response of resistant breast cancer cells to trastuzumab and lapatinib, both in vitro and in vivo. In conclusion, ALKBH5-mediated m6A demethylation of GLUT4 mRNA promotes resistance to HER2-targeted therapy, and targeting the ALKBH5/GLUT4 axis has therapeutic potential for treating patients with breast cancer refractory to HER2-targeted therapies. SIGNIFICANCE: GLUT4 upregulation by ALKBH5-mediated m6A demethylation induces glycolysis and resistance to HER2-targeted therapy and represents a potential therapeutic target for treating HER2-positive breast cancer.

Upregulation of endogenous TRAIL-elicited apoptosis is essential for metformin-mediated antitumor activity against TNBC and NSCLC.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) shows promising antitumor activity in preclinical studies. However, the efficacy of recombinant TRAIL in clinical trials is compromised by its short serum half-life and low in vivo stability. Induction of endogenous TRAIL may overcome the limitations and become a new strategy for cancer treatment. Here, we discovered that metformin increased TRAIL expression and induced apoptosis in triple-negative breast cancer (TNBC) and non-small cell lung cancer (NSCLC) cells. Metformin did not alter the expression of TRAIL receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5). Metformin-upregulated TRAIL was secreted into conditioned medium (CM) and found to be functional, since the CM promoted TNBC cells undergoing apoptosis, which was abrogated by a recombinant TRAIL-R2-Fc chimera. Moreover, blockade of TRAIL binding to DR4/DR5 or specific knockdown of TRAIL expression significantly attenuated metformin-induced apoptosis. Studies with a tumor xenograft model revealed that metformin not only significantly inhibited tumor growth but also elicited apoptosis and enhanced TRAIL expression in vivo. Collectively, we have demonstrated that upregulation of TRAIL and activation of death receptor signaling are pivotal for metformin-induced apoptosis in TNBC and NSCLC cells. Our studies identify a novel mechanism of action of metformin exhibiting potent antitumor activity via induction of endogenous TRAIL.

Bone Marrow-Derived Mesenchymal Stem Cells Modified with Akt1 Ameliorates Acute Liver GVHD.

BACKGROUND: Liver injury associated with acute graft-versus-host disease (aGVHD) is a frequent and severe complication of hematopoietic stem cell transplantation and remains a major cause of transplant-related mortality. Bone marrow-derived mesenchymal stem cells (BM-MSCs) has been proposed as a potential therapeutic approach for aGVHD. However, the therapeutic effects are not always achieved. In this study, we genetically engineered C57BL/6 mouse BM-MSCs with AKT1 gene and tested whether AKT1-MSCs was superior to control MSCs (Null-MSCs) for cell therapy of liver aGVHD. RESULTS: In vitro apoptosis analyses showed that, under both routine culture condition and high concentration interferon-γ (IFN-γ) (100ng/mL) stimulation condition, AKT1-MSCs had a survival (anti-apoptotic) advantage compared to Null-MSCs. In vivo imaging showed that AKT1-MSCs had better homing capacity and longer persistence in injured liver compared to Null-MSCs. Most importantly, AKT1-MSCs demonstrated an enhanced immunomodulatory function by releasing more immunosuppressive cytokines, such as IL-10. Adoptive transfer of AKT1-MSCs mitigated the histopathological abnormalities of concanavalin A(ConA)-induced liver injury along with significantly lowered serum levels of ALT and AST. The attenuation of liver injury correlated with the decrease of TNF-α and IFN-γ both in liver tissue and in the serum. CONCLUSIONS: In summary, BM-MSCs genetically modified with AKT1 has a survival advantage and an enhanced immunomodulatory function both in vitro and in vivo and thus demonstrates the therapeutic potential for prevention and amelioration of liver GVHD and other immunity-associated liver injuries.

BCR-ABL enhances the prolyl isomerase activity of Pin 1 by interacting with DAPK1 in ph+ ALL.

Philadelphia chromosome (Ph)/BCR-ABL-positive (ph+ ) ALL is the most common genetic abnormality associated with ALL and has been shown to confer the worst prognosis to both children and adults. Increasing evidence has revealed that the dysregulation of prolyl isomerase Pin 1 contributes to multicancer development and progression, including ALL, although the underlying molecular mechanisms remain unclear. Here, we report that the expression of Pin 1 was enhanced in ph+ ALL patient samples and was associated positively with the expression of BCR-ABL. Genetically or pharmacologically inhibiting Pin 1 expression or activity produces potent therapeutic efficacy against ph+ ALL. We further demonstrated that BCR-ABL enhances the prolyl isomerase activity of Pin 1 by decreasing the phosphorylated level of Pin 1 at Ser 71 and interacting with DAPK1. The inhibition of BCR-ABL activity by imatinib in human ph+ ALL cells reduces the prolyl isomerase activity of Pin 1, further suggesting a key role of the newly identified BCR-ABL-Pin 1 axis in ph+ ALL progression. Thus, the combined suppression of Pin 1 and BCR-ABL proteins may be exploited as an additional target therapy for ph+ ALL.

[Vascular endothelial injury induced by anti-endothelial cell antibody in allogeneic hematopoietic stem cell transplantation].

OBJECTIVE: To clarify the role of endothelial cells (ECs) injury induced by anti-endothelial cell antibody (AECA) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: Serum immunoglobulin (IgG) from allo-HSCT recipients were purified and incubated with human umbilical vein vascular endothelium (HUVEC) in vitro, then the functional changes and cell apoptosis were tested. RESULTS: After incubation with AECA positive IgG, soluble adhesion molecules significantly elevated in culture supernatant. When concentration of IgG was 160, 320, and 640 µg/ml, concentrations of soluble intercellular adhesion molecule-1 in supernatant were statistically higher in AECA positive groups [(117.10 ± 12.82) vs (78.17 ± 4.90) pg/ml, (151.30 ± 15.35) vs (89.46 ± 6.02) pg/ml, (239.00 ± 32.53) vs (127.80 ± 13.86) pg/ml, P<0.01)]. When concentration of IgG was 40, 80, 160, 320, and 640 µg/ml, concentrations of soluble vascular cell adhesion molecule-1 in supernatant were also statistically higher in AECA positive groups [(38.51 ± 3.76) vs (24.78 ± 2.59) pg/ml, (61.34 ± 6.99) vs (38.20 ± 3.17) pg/ml, (135.60 ± 24.46) vs (63.73 ± 5.08) pg/ml, (221.30 ± 29.40) vs (112.80 ± 8.91) pg/ml, (420.90 ± 31.70) vs (224.40 ± 20.79) pg/ml, P<0.01]. Clotting activity factors also elevated in culture supernatant after incubation with AECA positive IgG. When concentration of IgG was 80, 160, 320, and 640 µg/ml, concentrations of von Willebrand factor were statistically higher in AECA positive groups [(19.51 ± 0.72) vs (17.17 ± 0.60) ng/ml, P=0.0193; (22.97 ± 1.18) vs (18.27 ± 0.61) ng/ml, (26.40 ± 1.54) vs (19.53 ± 0.70) ng/ml, (34.35 ± 1.60) vs (23.81 ± 0.92) ng/ml, P<0.01]. When concentration of IgG was 320 and 640 µg/ml, concentrations of thrombomodulin were statistically higher in AECA positive groups [(57.50 ± 4.50) vs (40.31 ± 4.39) pg/ml, P=0.0132; (59.18 ± 4.11) vs (38.84 ± 5.16) pg/ml, P<0.01]. However, inflammatory factors (IL-1ß, IL-6, IL-8 and ANG2) were not statistically different in AECA positive and negative groups (P>0.05). Moreover, IgG from AECA positive samples did not change the proliferation or cell apoptosis. CONCLUSION: AECA from allo-HSCT recipients dysregulates ECs' function in vitro, but do not induce apoptosis, which is valuable in the pathophysiology of graft-versus-host disease (GVHD) and other complications after allo-HSCT.

[Comparison of outcomes of adult acute lymphoblastic leukemia patients underwent autologous and allogeneic hematopoietic stem cell transplantation].

OBJECTIVE: To compare the outcomes of adult patients with acute lymphoblastic leukemia (ALL) who underwent autologous hematopoietic stem cell transplantation (auto-HSCT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: From Jan 2007 to Dec 2010, 106 adult ALL patients were retrospectively divided into two groups, 50 in auto-HSCT group and 56 in allo-HSCT group. Auto-HSCT group included 21 patients with high-risk, 46 patients in CR1 and 4 cases in CR2. All the 50 patients had negative minimal residual disease (MRD) prior to HSCT. Allo-HSCT group included 44 patients with high risk, 51 patients in CR1 and 5 cases in CR2, 15 patients with positive MRD before allo-HSCT. response, regulatory T cells (Treg), cytokines levels and treatment-related adverse effects were observed. RESULTS: Of the total 106 patients, 29 patients relapsed at a medium follow-up of 22.9(0.8-63.3) months. The 3-year cumulative relapse rate (RR) was (29.9±8.0) % in auto-HSCT group and (32.7±6.8) % in allo-HSCT group. There were no significant differences in RR and overall survival (OS) between auto-HSCT and allo-HSCT groups, even of stratified risk groups. In standard risk group, 3-year OS was (77.1±13.2) % in auto-HSCT group and (90.9±8.7) % in allo-HSCT group (P=0.739). In high-risk group, 3-year OS was (68.7±10.8) % after auto-HSCT and (45.2±8.5) % after allo-HSCT (P=0.094). CONCLUSION: Due to acceptable RR and OS, adult ALL patients with no MRD before HSCT showed favorable survival. Auto-HSCT may be a considerable choice for adult ALL patients with negative MRD when lacking of donors for allo-HSCT.

[Outcome analysis of alternative donor allogeneic hematopoietic cell transplantation in the treatment of 19 severe aplastic anemia patients].

OBJECTIVE: To evaluate the efficacy of alternative donor allogeneic hematopoietic stem cell transplantation (AD allo-HSCT) in the treatment of severe aplastic anemia (SAA). METHODS: Retrospective analysis of the clinical data of 19 SAA patients received AD allo-HSCT from May 2003 to December 2012. Of them, 12 received haploidentical HSCT (haplo-HSCT), 7 received unrelated donor transplantation. The conditioning regimen was CY+ATG+Flu±Ara-C±Bu/Mel, the GVHD preventing regimen was MMF+MTX+CSA/FK506; the median reinfusion quantity of CD34+ was 3.10(2.11-4.38)×106/kg in allo-BMT and 4.90(2.08-6.88)×106/kg in allo-PBSCT. RESULTS: Hematopoiesis reconstitution was achieved in all 19 patients. Twelve patients developed acute graft-versus-host disease (aGVHD), and 7 developed chronic GVHD (cGVHD). Graft rejection (GR) was occurred in one patient. The median follow-up time was 13(3-115) months. Thirteen patients survived, and the prospective 5-year overall survival rate is (67.5±11.0)%. CONCLUSION: AD allo-HSCT can be used as an alternative therapy for SAA patients without HLA matched sibling donor.

Clinical significance of anti-endothelial cell antibody in allogeneic hematopoietic stem cell transplantation recipients with graft-versus-host disease.

Anti-endothelial cell antibody (AECA) is well known to reflect endothelial injury. Graft-versus-host disease (GVHD), a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT), is also closely associated with endothelial injury. We hypothesized that AECA may be associated with GVHD. To investigate the clinical significance of AECA in allo-HSCT recipients with GVHD, we detected AECA by cyto-enzyme-linked immunosorbent assay (cyto-ELISA) in allo-HSCT recipients with acute and/or chronic GVHD (aGVHD and cGVHD). Incidences of anti-HMEC-1 AECA (anti-HMEC) and anti-EA.hy926 AECA (anti-EAHY) were significantly higher in patients with grade II-IV than grade 0-I aGVHD (P = 0.049, P = 0.011, respectively). There was no difference in the incidence of AECA between patients with and without cGVHD. Patients with anti-EAHY positive in the early stage post-transplant demonstrated a higher incidence of cGVHD (P = 0.044). In patients with grade 0-I aGVHD, AECA-positive patients had higher overall survival and disease-free survival (P < 0.05), and tended to have lower incidences of relapse and transplant-related mortality. Our data suggest that AECA plays an important role in the pathogenesis of GVHD.

[Outcome of allogeneic hematopoietic stem cell transplantation from HLA-matched sibling donor for 41 cases of severe aplastic anemia].

OBJECTIVE: To evaluate the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) from HLA-matched sibling donor (MSD allo-HSCT) for severe aplastic anemia (SAA). METHODS: The clinical data of 41 SAA patients received MSD allo-HSCT from May. 2003 to Aug. 2011 were analyzed retrospectively. 24 patients were male, 17 were female. Median age was 23 (5 - 43) years old. 28 patients had SAA-I, 9 had SAA-II, and 4 had post-hepatitis aplastic anemia. 17 patients received allogeneic bone marrow (BM) transplantation (allo-BMT), and 24 received allogeneic peripheral blood stem cell (PBSC) transplantation (allo-PBSCT). The conditioning regimens: 20 patients received cyclophosphamide (CY) + anti-thymocyte globulin (ATG) + fludarabine (Flu), 21 received CY + ATG + Flu+ cytarabine (Ara-C) ± busulfan (Bu)/melphalan (Mel). Prophylaxis for graft-versus-host disease (GVHD): 25 patients received cyclosporine (CSA) plus short-term methotrexate (MTX), 16 received tacrolimus (FK506) plus short-term MTX. The median number of infused CD34(+) cells were 3.48 (2.39 - 4.80)×10(6)/kg in allo-BMT and 2.95 (1.27 - 5.98)×10(6)/kg in allo-PBSCT, respectively. RESULTS: Hematopoietic reconstitution was observed in all 41 patients (100%). The median time of neutrophils (ANC) reached to 0.5×10(9)/L and platelets (PLT) reached to 20×10(9)/L were 14 (10 - 23) days and 19 (8 - 38) days, respectively. 12 patients developed acute GVHD (aGVHD), out of which 11 developed grade I-II aGVHD, and one developed grade IV. 2 patients occurred chronic GVHD (cGVHD), out of which one with local cGVHD and the other with extensive. 4 patients occurred graft rejection (GR), all of them recovered haemopoiesis and survived after donor PBSC infusion. 5 patients (12.2%) died, out of which one died of extensive cGVHD, and 4 died of invasive fungal infections (IFI). Median follow-up time was 23 (3 - 79) months. 36 patients survived. 5-year estimated overall survival (OS), disease free survival (DFS), and transplant-related mortality (TRM) was (81.1 ± 9.0)%, (68.4 ± 11.0)%, and (18.9 ± 9.0)%, respectively. Univariate analysis showed that lover OS had significant correlation with receiving PBSCT, occurrence of aGVHD, the number of infused CD34(+) cells no more than 2.5×10(6)/kg, the number of red blood cell (RBC) transfusion before transplant more than 30 U and occurrence of IFI after transplantation (P = 0.034, 0.001, 0.006, 0.000, 0.001, respectively). Occurrence of aGVHD had significant correlation with the disparity between donor and recipient ABO blood groups, the number of PLT transfusion more than 100 U, and the number of RBC transfusion more than 30 U before transplantation, the number of infused CD34(+) cells no more than 2.5× 10(6)/kg (P = 0.019, 0.038, 0.005, 0.005, respectively). The occurrence of GR had significant correlation with the number of PLT transfusion more than 100 U before transplantation (P = 0.038). CONCLUSION: MSD allo-HSCT is an effective therapy for patients with SAA. Lower number of blood transfusion before transplantation, use of BMT, more number of infused CD34(+) cells can effectively prevent and treat aGVHD and IFI after transplantation, which may improve the efficacy of MSD allo-HSCT for SAA.