Motonori Mizutani

Importance of Glutamine Metabolism in Leukemia Cells by Energy Production Through TCA Cycle and by Redox Homeostasis

Some cancer cells depend on glutamine despite of pronounced glycolysis. We examined the glutamine metabolism in leukemia cells, and found that HL-60 cells most depended on glutamine in the 4 acute myelogenous leukemia (AML) cell lines examined: growth of HL-60 cells was most suppressed by glutamine deprivation and by inhibition of glutaminolysis, which was rescued by tricarboxylic acid (TCA) cycle intermediate, oxaloacetic acid. Glutamine is also involved in antioxidant defense function by increasing glutathione. Glutamine deprivation suppressed the glutathione content and elevated reactive oxygen species most evidently in HL-60 cells. Glutamine metabolism might be a therapeutic target in some leukemia.

Leukemia cells demonstrate a different metabolic perturbation provoked by 2-deoxyglucose.

The shift in energy metabolism from oxidative phosphorylation to glycolysis can serve as a target for the inhibition of cancer growth. Here, we examined the metabolic changes induced by 2-deoxyglucose (2-DG), a glycolysis inhibitor, in leukemia cells by metabolome analysis. NB4 cells mainly utilized glucose as an energy source by glycolysis and oxidative phosphorylation in mitochondria, since metabolites in the glycolytic pathway and in the tricarboxylic acid (TCA) cycle were significantly decreased by 2-DG. In THP-1 cells, metabolites in the TCA cycle were not decreased to the same extent by 2-DG as in NB4 cells, which indicates that THP-1 utilizes energy sources other than glucose. TCA cycle metabolites in THP-1 cells may be derived from acetyl-CoA by fatty acid β-oxidation, which was supported by abundant detection of carnitine and acetylcarnitine in THP-1 cells. 2-DG treatment increased the levels of pentose phosphate pathway (PPP) metabolites and augmented the generation of NADPH by glucose-6-phosphate dehydrogenase. An increase in NADPH and upregulation of glutathione synthetase expression resulted in the increase in the reduced form of glutathione by 2-DG in NB4 cells. We demonstrated that a combination of 2-DG and inhibition of PPP by dehydroepiandrosterone (DHEA) effectively suppressed the growth of NB4 cells. The replenishment of the TCA cycle by fatty acid oxidation by carnitine palmitoyltransferase in THP-1 cells, treated by 2-DG, might be regulated by AMPK, as the combination of 2-DG and inhibition of AMPK by compound C potently suppressed the growth of THP-1 cells. Although 2-DG has been effective in preclinical and clinical studies, this treatment has not been fully explored due to concerns related to potential toxicities such as brain toxicity at high doses. We demonstrated that a combination of 2-DG and DHEA or compound C at a relatively low concentration effectively inhibits the growth of NB4 and THP-1 cells, respectively. These observations may aid in the identification of appropriate combinations of metabolic inhibitors at low concentrations which do not cause toxicities.

Growth of xenotransplanted leukemia cells is influenced by diet nutrients and is attenuated with 2-deoxyglucose

We examined the effects of diet nutrients on xenotransplanted leukemia cells, THP-1 or NB4. THP-1 tumors showed more growth when fed with high fat diet, while NB4 tumors grew more with high carbohydrate diet. Then, administration of 2-deoxyglucose (a glycolysis inhibitor) showed a significant antitumor effect on both tumors: NB4 tumor showed large necrotic areas, while THP-1 tumor did not, but had augmented expression of enzymes for fatty acid oxidation. 2-Deoxyglucose inhibited the growth of NB4 by cell death because main energy producing pathway (glycolysis) was abolished, while 2-deoxyglucose slowed the growth of THP-1 by shifting energy metabolism to fatty acid β-oxidation.

Comparison of Autologous and Unrelated Transplants for Cytogenetically Normal Acute Myelogenous Leukemia

Allogeneic stem cell transplantation (SCT) from an HLA-matched sibling donor (MSD) is a postremission treatment that offers a potential cure for adults with cytogenetically normal (CN) acute myelogenous leukemia (AML) in first complete remission (CR1). The best alternative in the absence of an MSD remains unclear, however. The aim of this study was to retrospectively compare the outcomes of autologous peripheral blood stem cell transplantation (auto-PBSCT; n = 177) and allogeneic bone marrow transplantation (BMT) from an HLA-matched unrelated donor (MUD; n = 173) in adult patients with CN-AML/CR1. Both the multivariate analysis (hazard ratio [HR], 1.18; 95% confidence interval [CI], 0.71 to 1.97; P = .53) and propensity score models (HR, 1.40; 95% CI, 0.80 to 2.43; P = .24) indicated that the leukemia-free survival (LFS) rate of auto-PBSCT was not significantly different from that of MUD-BMT. These results suggest that in the absence of an available MSD, auto-PBSCT remains a viable alternative as postremission therapy in patients with CN-AML/CR1.

A case of chronic kidney disease with thrombotic microangiopathy in a hematopoietic stem cell transplant recipient

A 23-year-old Japanese man who had undergone hematopoietic stem cell transplantation for acute lymphocytic leukemia from an HLA-identical sibling 6 years earlier developed proteinuria and impaired kidney function. Kidney biopsy revealed thrombotic microangiopathy with a moderate increase in mesangial matrices and glomerular microaneurysm featuring retention of red blood cells. The patient’s kidney function gradually deteriorated, requiring the institution of treatment with angiotensin II receptor blockers and angiotensin-converting enzyme inhibitors, and progressing to continuous ambulatory peritoneal dialysis 4 years after the initial kidney biopsy. Eventually, kidney transplantation was performed with his mother as the donor. His kidney function is stable on immunosuppressive drugs at 2 years after transplantation. This report reflects the growing number of patients with chronic kidney disease with thrombotic microangiopathy all over the world.

The recipient CCR5 variation predicts survival outcomes after bone marrow transplantation

The chemokine receptor CCR5 plays roles in the trafficking of effector cells towards the site of inflammation. We retrospectively examined the impact of the CCR5 variation (rs1800023, -2086A>G) on transplant outcomes in a cohort of 329 patients who underwent unrelated HLA-matched bone marrow transplantation (BMT) for hematologic malignancies through the Japan Marrow Donor Program. A multivariate analysis showed that the recipient CCR5 -2086A/A genotype was significantly associated with a lower relapse rate but not with the development of graft-versus-host disease (GVHD) or transplant-related mortality, thereby resulting in better disease-free and overall survival rates than other variations. The donor CCR5 -2086A/A genotype was associated with a lower incidence of grades 3-4 acute GVHD, which did not improve the survival outcomes. These findings suggest that the recipient CCR5 -2086A/A genotype affects the induction of the graft-versus-tumor effect without augmenting the development of GVHD. CCR5 genotyping in transplant recipients may therefore be a useful tool for evaluating pretransplantation risks.

Toll-like receptor genetic variations in bone marrow transplantation

The Toll-like receptor family mediates the innate immune system through recognizing the molecular patterns of microorganisms and self-components and leading the synthesis of the inflammatory mediators. We retrospectively examined whether or not genetic variations in toll-like receptor 1 (rs5743551, -7202GQ>A), toll-like receptor 2 (rs7656411, 22215G>T), and toll-like receptor 4 (rs11536889, +3725G>C) affected transplant outcomes in a cohort of 365 patients who underwent unrelated HLA-matched bone marrow transplantation (for hematologic malignancies through the Japan Marrow Donor Program. Only donor toll-like receptor 4 variation significantly improved the survival outcomes. A multivariate analysis showed that the donor toll-like receptor 4 +3725G/G genotype was significantly associated with a better 5-year progression-free survival and a lower 5-year transplant-related mortality than other variations. Furthermore, the donor toll-like receptor 4 +3725G/G genotype was associated with a significantly lower incidence of fatal infections than other variations. The validation study of 502 patients confirmed that the donor toll-like receptor 4 +3725G/G genotype was associated with better survival outcomes. Toll-like receptor4 genotyping in transplant donors may therefore be a useful tool for optimizing donor selection and evaluating pretransplantation risks.

Toll-like receptor 1 variation increases the risk of transplant-related mortality in hematologic malignancies

Toll-like receptor 1 (TLR1) genetic variant (rs5743551, -7202A>G) has been reported to be associated with susceptibility to various infectious diseases. We retrospectively examined the impact of TLR1 variation on transplant outcomes in a cohort of 320 patients who underwent unrelated HLA-matched bone marrow transplantation (BMT) for hematologic malignancies. A multivariate analysis showed that the G/G genotype in the recipients and the donors was associated with a significantly lower 3-year transplant-related mortality (TRM). The recipient G/G genotype also resulted in a better 3-year progression-free survival. This study suggests that the recipient and donor TLR1 G/G genotypes are comparably associated with a reduced risk of death that was not related to relapse. Thus, TLR1 genotyping may be useful for selecting the donor, managing patients in a risk-adapted manner, and creating therapeutic strategies to prevent complications after hematopoietic stem cell transplantation.

Overexpression of salivary-type amylase reduces the sensitivity to bortezomib in multiple myeloma cells

Amylase-producing myeloma exhibits refractoriness to chemotherapy and a dismal prognosis. In this study, we established a human myeloma cell line, 8226/AMY1, in which a lentivirally transfected AMY1 gene was stably expressed and explored its biological characteristics. 8226/AMY1 showed a survival advantage over mock control when treated with dexamethasone, bortezomib, and lenalidomide in vitro partly through inhibition of apoptosis induced by these reagents. In a xenograft murine model, 8226/AMY1 showed rapid tumor growth and reduced sensitivity to bortezomib compared with mock. A microarray gene expression analysis identified TCL1A, which functions as a coactivator of the cell survival kinase Akt, differentially up-regulated in 8226/AMY1. The expression of phosphorylated Akt was increased in the 8226/AMY1 cells following bortezomib treatment, but not in the mock cells. In addition, treatment with perifosine, an inhibitor of Akt phosphorylation, enhanced the anti-myeloma effect of bortezomib in the 8226/AMY1 cells. Our data suggest that amylase-producing myeloma reduced the sensitivity to bortezomib in vitro and in vivo, and the up-regulation of TCL1A may influence the drug susceptibility of 8226/AMY1 via the phosphorylation of Akt. These findings provide clues for developing treatment approaches for not only amylase-producing myeloma, but also relapsed and refractory myelomas.