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Leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) are quiescent, insensitive to BCR-ABL1 tyrosine kinase inhibitors (TKIs) and responsible for CML relapse. Therefore, eradicating quiescent CML LSCs is a major goal in CML therapy. Here, using a novel G0 marker (G0M), we narrowed down CML LSCs as G0M- and CD27- double positive cells among the conventional CML LSCs. Whole transcriptome analysis revealed NF-κB activation via inflammatory signals in imatinib-insensitive quiescent CML LSCs. Blocking NF-κB signals by IRAK1/4 inhibitors together with imatinib eradicated mouse and human CML LSCs. Intriguingly, IRAK1/4 inhibitors attenuated PD-L1 expression on CML LSCs, and blocking PD-L1 together with imatinib also effectively eradicated CML LSCs in the presence of T cell immunity. Thus, IRAK1/4 inhibitors could eradicate CML LSCs through inhibiting NF-ΚB activity and reducing PD-L1 expression. Collectively, the combination of TKIs and IRAK1/4 inhibitors is an attractive strategy to achieve a radical cure of CML.

Myelodysplastic syndrome (MDS) is a clonal disorder of hematopoietic stem cells (HSCs), characterized by ineffective hematopoiesis and frequent progression to leukemia. It has long remained unresolved how MDS cells, which are less proliferative, inhibit normal hematopoiesis and eventually dominate the bone marrow space. Despite several studies implicating mesenchymal stromal or stem cells (MSCs), a principal component of the HSC niche, in the inhibition of normal hematopoiesis, the molecular mechanisms underlying this process remain unclear. Here, we demonstrate that both human and mouse MDS cells perturb bone metabolism by suppressing the osteolineage differentiation of MSCs, which impairs the ability of MSCs to support normal HSCs. Enforced MSC differentiation rescues the suppressed normal hematopoiesis in both in vivo and in vitro MDS models. Intriguingly, the suppression effect is reversible and mediated by extracellular vesicles (EVs) derived from MDS cells. These findings shed light on the novel MDS EV-MSC axis in ineffective hematopoiesis.

一般社団法人 日本放射線看護学会 第９回学術集会 抄録集に掲載 【目的】患者にやさしい治療法とされている放射線治療は、線量の病巣への集中化を図るための機器・技術開発が急速に進められている。副作用（有害事象）の発生の可能性が高い放射線治療では、副作用など患者自らも観察し記録し、治療に積極的に係わっていくことが、放射線治療を効果的に進めるうえで重要である。そこで、患者も記入できる「放射線治療手帳」の利用を図っていきたいと考え、今回プロトタイプの手帳を作成した。放射線治療手帳の利用により、医療機関の患者情報の共有ができ、チーム医療の推進にもつながると考えている。, 一般社団法人 日本放射線看護学会 第９回学術集会

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder caused by constitutively active BCR-ABL1 tyrosine kinase resulting from the t(9;22) Philadelphia translocation. Imatinib, a BCR-ABL1 tyrosine kinase inhibitor (TKI), is a revolutionary molecular target inhibitor for CML. However, leukemic stem cells (LSCs) eventually become resistant to imatinib and thereby cause relapse. The next-generation BCR-ABL1 TKI dasatinib is also unable to eliminate CML LSCs. On the other hand, the third-generation BCR-ABL1 TKI ponatinib is not well studied in terms of its efficacy on CML LSCs. Here, we evaluate the efficacy of ponatinib against CML LSC-containing lin–Sca-1+c-Kit+ (LSK) cells using a mouse CML-like model. To this end, we compared the efficacy of imatinib, dasatinib, and ponatinib on CML LSK cells and showed that ponatinib is more effective at eliminating CML LSK cells. Our results suggest that ponatinib could be potentially useful for achieving treatment-free remission in CML patients.

Myelodysplastic syndromes (MDS) is a clonal disorder of hematopoietic stem cells (HSCs) characterized by clonal hematopoietic stem cells (HSCs) with cytopenia, morphological abnormalities, genetic alteration, ineffective normal hematopoiesis, and frequent progression to AML. It has long remained unresolved how MDS cells, which are less proliferative, inhibit normal hematopoiesis and eventually come to dominate the bone marrow space. Despite several studies of mesenchymal stem cells (MSCs), one of the principal components of HSC niche supporting normal hematopoiesis, the molecular mechanisms underlying this process remain unclear. In this study, we examined the mechanism by which less-proliferative MDS cells outcompete normal hematopoiesis through the effects on MSCs using serially transplantable Abcg2-induced MDS/AML model we recently generated. The recipient-derived normal BM cells displayed a considerably lower colony output with markedly decreased numbers of the hematopoietic stem progenitor cells (HSPCs) . However, there were no direct effects on the colony-forming ability of the recipient HSPCs co-cultured with MDS/AML cells, indicating that MDS/AML cells inhibited hematopoiesis through alteration of bone marrow microenvironment, such as MSCs, rather than direct interaction between normal and malignant HSCs. We next analyzed histological features of BM specimens. Interestingly, bone sections from the MDS/AML mice showed a reduced trabecular bone and narrowed growth plates. Moreover, micro computed tomography (micro-CT) analysis of the femora showed a significant reduction of the trabecular bone volume in the recipient mice transplanted with the MDS/AML BM cells. We detected decreased bone formation based on the calcein double labeling, but unchanged numbers of the TRAP-positive mononuclear or multinucleated (osteoclastic) cells in the MDS/AML samples, suggesting that the reduced bone volume was caused by suppressed bone formation. The impaired bone formation was also observed in the human MDS patients in terms of lower bone volume and decreased expression of BGLAP, one of osteogenic markers. In line with the above findings, single cell qRT-PCR analyses of mouse MSCs displayed downregulation of a line of osteolineage markers, indicating that MDS/AML cells suppress bone formation through inhibiting osteolineage differentiation of MSCs. Based on the findings, we next examined if re-induction of osteolineage differentiation of the MDS/AML-derived MSCs could rescue the potential of MSCs to support normal hematopoiesis. Importantly, the number of colony-forming cells (CFCs) was significantly restored by inducing differentiation of MDS/AML-derived MSCs toward osteogenic lineage both in vitro and in vivo. These results indicate that the impairment of osteolineage differentiation is the principal cause for an impaired normal hematopoiesis in MDS/AML, and that restoring the supportive niche will be a potential therapeutic option. Since extracellular vesicles (EVs) derived from MDS/AML cells are critical mediators of intercellular communication, we examined the molecular mechanism underlying the dysfunction of MSCs via EVs. As expected, EVs from MDS/AML cells were incorporated into the normal MSCs where osteolineage marker genes were clearly downregulated, and the number of CFCs significantly decreased in the HSPCs co-cultured with MSCs treated by the MDS/AML-derived EVs. Moreover, by comprehensively analyzing microRNAs (miRNAs) enriched in EVs derived from MDS/AML cells, we identified several miRNAs that impaired the differentiation of normal MSCs. These results suggested that miRNAs in EVs derived from MDS/AML cells disrupted the hematopoietic supporting niche through suppressing an osteolineage differentiation of MSCs. Here we uncover a heretofore unrecognized mechanism of bone marrow failure in MDS via the impairment of osteolineage differentiation in MSCs. EVs from MDS cells will be an attractive therapeutic target to restore the supportive niches, such as MSCs, for the remaining normal HSCs. Figure Disclosures No relevant conflicts of interest to declare.

Quiescent hematopoietic stem cells (HSCs) are typically dormant, and only a few quiescent HSCs are active. The relationship between “dormant” and “active” HSCs remains unresolved. Here we generated a G0 marker mouse line that visualizes quiescent cells. The G0 marker identifies a population of active HSCs (G0 markerlow) which are rare and distinct from dormant HSCs (G0 markerhigh) within the conventional quiescent HSC fraction. Single-cell RNA-sequencing analyses showed that the gene expression profiles of these populations were nearly identical, yet differed in their Cdk4/6 activity. Furthermore high-throughput small molecule screening revealed that high levels of basal cytoplasmic calcium (Ca2+) protected the dormancy of HSCs from cell cycle activation induced by calcium influx. These findings indicate that the G0 marker separates dormant and active adult HSCs, which are regulated by Cdk4/6 and Ca2+ levels. This G0 marker mouse line represents a useful new resource for investigating physiologically important stem cell subpopulations.

The effects of ethanol (12.5-500 mM for up to 24 h) on mitochondrial structure including that of ATPase particles in cultured ventricular myocardial cells were studied using negative-stain electron microscopy. The activity of mitochondrial ATPase after ethanol treatment was also examined cytochemically and biochemically. At 5 min after the addition of all the concentrations of ethanol examined, some mitochondrial cristae were expanded and the arrangement of mitochondrial ATPase particles on these cristae was disordered. At and after 30 min the cristae decreased in number and some were expanded, vesiculated or fragmented. ATPase particles also decreased in number, particularly after the application of ethanol in concentrations of more than 50 mM. All the mitochondria had broadened and translucent cristae, and lacked ATPase particles with 200 and 500 mM ethanol at 24 h, although with 12.5 and 50 mM ethanol some mitochondria had similar negatively stained images but others had ATPase particles on broadened cristae. The enzymatic activity of the mitochondrial ATPase was unchanged with 200 and 500 mM ethanol at 24 h, compared with controls. The cytochemical technique also detected enzyme activity with all the concentrations of ethanol examined at 24 h. The discrepancy between the structural and biochemical alterations in mitochondrial ATPase induced by ethanol is discussed.

Myocardial cells in monolayer culture were examined ultrastructurally at various times (5 min-24 hr) after addition of ethanol (12.5-500 mM). At 5 min, all concentrations of ethanol induced mitochondrial fusion and a remarkable increase in glycogen granules, and the mitochondrial outer membrane seemed more fragile. These initial ultrastructural changes then recovered with time. Glycogen granules were decreased, then returned to normal more rapidly as the ethanol concentration was increased. Mitochondrial fusion and fragile appearance of the outer membrane were hardly seen at 1 hr in the presence of 12.5 or 50 mM ethanol, but were still evident with higher ethanol concentrations (200 and 500 mM), though less frequently than at 5 and 30 min. Furthermore, 'giant mitochondria' (with at least a five-fold increase in sectional area) appeared in the presence of 200 and 500 mM ethanol with increasing time of exposure. These results are discussed in relation to the direct effects of ethanol.

To study the cytophysiological effects of ethanol systematically, L929 cells, a fibroblastic cell line derived from mouse connective tissue, were exposed to various concentrations of ethanol (12.5, 50, 100 and 200 mM) for short (3 and 6 h) and longer (24 or 26 h) durations. Ethanol-induced cellular responses were analysed by a combination of the following assays: number of cells, amounts of DNA and protein, MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay and cell cycle. Ethanol dose-dependently suppressed these cellular functions, except that 12.5 mM exposures for both 6 and 26 h increased the amount of protein in spite of almost no change in other cellular functions, compared to the control. The most marked dose-dependency was observed in a reduction of formazan product in an MTT assay after both 6 and 26 h exposures to ethanol, being independent of the number of cells and probably reflecting dose-dependent depression of mitochondrial respiration. A G2 + M block in the cell cycle, an inhibition of cell division, was induced after short-term exposures (3 and 6 h) to 100 and 200 mM ethanol, but the block was released before 24 h had passed. Alternatively, prolonged exposures (24 h) to 50-200 mM ethanol induced a G0/G1 block, resulting in a decrease in the amount of DNA below the control value. Moreover, the percentage of the S phase was decreased gradually and dose-dependently throughout the 24 h exposure. Thus, high concentrations of ethanol (50, 100 and 200 mM) perturbed the cell cycle progression by causing both a transient G2 + M block (an inhibition of mitosis) and a continuous G0/G1 block, though the latter was masked by the G2 + M block during short-term exposure. The cells seem finally to acquire some tolerance to ethanol so as to pass through mitosis, but much less tolerance to pass through the checkpoint from the G1 to the S phase, which results in a decline in proliferation.

The plasmin digestion of factor XIII in the plasma with congenital afibrinogenemia has been reported by Suzuki et al. (1967).The present investigation is attempted to obtain some new aspects in the biochamical changes of factor XIII during the degradation with plasmin. The authors advanced the polyacrylamide disc electrophoresis and the cross-immunoelectrophoresis with anti-factor XIII (A & S) serum for the detection of molecular change of factor XIII and our modified method for the assay of factor XIII activity. In summary, it is concluded that the process of plasmin digestion of factor XIII can be divied into three steps described below.The first step; the subunit A of factor XIII such as placental factor XIII is ready to get plasmin digestion following the decrease of amount and activity of subunit A.The second step; in the observation of the subunit A2S complex like plasma factor XIII, the subunit S portion in the complex is more readily affected by. the plasmin digestion than the subunit A of the complex. Therefore, it is assumed that the subunit S may be play a protective role against the plasmin attack on the subunit A of the subunit A2S complex.The third step; subunit A2S complex coexisting with fibrinogen or plasma protein is fairly stable on exposure to plasmin. According to the results mentioned above, the mechanism of the plasmin digestion of factor XIII becomes highly complex by the inhibitory effects of the combination with subumit S or plasma protain including fibrinogen.It may be tentatively explained that the decrease of the factor XIII in afibrinogemia and DIC may be due to the consumption of factor XIII during the process of blood coagulation, and the plasmin digestion of the subunit A in the tissues and in the plasma by the local or secondary fibrinolysis with diminished plasma fibrinogen concentration.