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Acute lymphoblastic leukemia (ALL) is characterized by the accumulation of abnormal lymphoblasts in the bone marrow and blood. Though great progress has been made for improvement in clinical treatment during the past decades, some children with ALL still relapsed. Glucocorticoid (GC) resistance is an important clinical problem for ALL treatment failure. Therefore, further understanding of the mechanism of GC resistance and exploring novel therapeutic strategies are crucial for improving treatment outcome. The reported involvement of microRNAs (miRNAs) in drug resistance implied that deregulated miRNA expression might contribute to GC treatment response of ALL. However, individual miRNAs and their functional mechanisms potentially involved in the GC response are still largely unknown. In the present study, we found that miR-124 was up-regulated in prednisone insensitive human ALL cell line and prednisone-poor response ALL patients. Furthermore, it was found that miR-124 might contribute to GC resistance by promoting proliferation and inhibiting apoptosis of ALL cells. Importantly, we validated that miR-124, targeted and decreased the expression of glucocorticoid receptor (NR3C1), prevented the inhibitory effect of GC in ALL. These findings strongly suggest that miR-124 is critical in poor GC response and may serve as a potential therapeutic target in ALL with poor GC resistance. [ABSTRACT FROM AUTHOR]

Leukemias arising from immature nature killer (NK) cells have been proposed as distinct entities and are rare. Treatment and prognosis of these diseases are controversial, and data on children are limited. According to the literature, one of these distinct leukemias may be myeloid/NK cell precursor acute leukemia (MNKPL), with the blasts being cytochemically myeloperoxidase negative (MPO−−) and phenotypically CD56++CD3−−CD7++CD34++ and myeloid antigens++. The other may be myeloid/NK cell acute leukemia (MNKL), in which the blasts were cytochemically MPOdim and phenotypically CD56++CD16−−CD3−−CD33++HLA-DR−−. Between 2005 and 2008, 4 MNKPL and 1 MNKL children aged 1.3 to 12.5 years were encountered in the First Affiliated Hospital of Sun Yat-Sen University. In those with MNKPL, remarkable extramedullary involvement usually occurring in adults was not observed; however, myelofibrosis was found in 2 children. The child with MNKL abandoned treatment. Those with MNKPL were treated with a protocol designed for childhood high-risk acute lymphoblastic leukemia (ALL) containing cytarabine, mitoxantrone, etoposide, l-asparaginase, and methotrexate according to the myeloid and lymphoid characteristics of MNKPL. They responded slowly to chemotherapy and were in complete remission (CR) for 26 to 63 months, except 1 who died in CR from pneumonia. They had longer survival and seemed to have a better outcome than those reported previously. In conclusion, childhood leukemias with immature NK cell markers may have different characteristics from their adult counterparts. A protocol including agents used for acute myeloid leukemia combined with those for ALL is seemingly effective for treatment of MNKPL. However, a modified treatment strategy designed more specifically for MNKPL and longer observations are needed. [ABSTRACT FROM AUTHOR]

MLL-rearranged leukemia is an aggressive malignancy associated with poor outcome, which is refractory to conventional treatment. Melatonin has been proven to exert anti-tumor activity, but the effect of melatonin on MLL-r leukemia and the underlying mechanism remain poorly understood. In this study, melatonin inhibited cell proliferation and induced apoptosis by activating the caspase-dependent apoptotic pathway in MLL-r leukemia cells. Mechanistic investigations revealed that melatonin suppressed the expression of hTERT by abrogating the binding activity of RBFOX3 to the hTERT promoter. Melatonin also blocked NF-κB nuclear translocation and suppressed NF-κB binding to the COX-2 promoter, thereby suppressing the expression of COX-2. In addition, clinical samples revealed that melatonin exerts anti-leukemic activity in primary MLL-r leukemia blasts ex vivo. In vivo, the mice treated with melatonin experienced a larger reduction in leukemic burden than the control group in a MLL-r leukemia xenograft mouse model. Collectively, these results suggest that melatonin inhibits MLL-rearranged leukemia through suppressing the RBFOX3/hTERT and NF-κB/COX-2 signaling pathways. Our findings provide new insights into the role of melatonin for MLL-r leukemia treatment. [ABSTRACT FROM AUTHOR]

FLT3-ITD mutations occur in approximately 30% of acute myeloid leukemia (AML) and are associated with a poor outcome. Currently available FLT3 inhibitors havein vitrobut limited clinical activity in FLT3-ITD AML. Reports have shown that an arsenic trioxide (ATO)/all-trans-retinoic acid (ATRA) combination improves prognosis in acute promyelocytic leukemia, especially with FLT3-ITD, and ATO or ATRA alone enhances apoptosis in FLT3-ITD AML cells treated with FLT3 inhibitors, providing a rationale to investigate the role of ATO/ATRA in FLT3-ITD AML. Here, we demonstrate that an ATO/ATRA combination selectively exerts synergistic cytotoxicity against FLT3-ITD AML cell lines (MV4;11/MOLM-13). The signaling pathways affected by ATO/ATRA include FLT3/STAT5/MYC, FLT3/STAT5/E2F1, FLT3/ERK/ATF5 and FLT3/AKT/ATF5.ATF5 may function as an oncogene in FLT3-ITD AML. Our findings provide experimental evidence that supports further exploration of ATO/ATRA in FLT3-ITD AMLin vivoand warrants a clinical evaluation of regimens comprising an ATO/ATRA combination. [ABSTRACT FROM PUBLISHER]

The development of novel chemotherapeutic drugs is needed for the treatment of patients with acute lymphoblastic leukemia (ALL). In this study, the anti-leukemic effect and the potential molecular mechanisms of action of flavokawain B on ALL were investigated. Flavokawain B was found to significantly inhibit the cellular proliferation of B-ALL and T-ALL cell lines in a dose-dependent manner. It also induced cellular apoptosis by increasing the expression of p53, Bax and Puma, and activating the cleavage of caspase-3 and poly ADP-ribose polymerase (PARP). Furthermore, the enhancement of p53-dependent apoptosis by flavokawain B could be rescued by pifithrin-α, a pharmacological inhibitor of p53 transcriptional activity. Moreover, the proliferation of leukemia blast cells from 16 patients with ALL was inhibited by flavokawain B, and tumor growth in xenograft mice was also suppressed by this drug. In conclusion, our results demonstrate the therapeutic potential of flavokawain B for the treatment of ALL. [ABSTRACT FROM PUBLISHER]

Objective To investigate the effects of early nutritional intervention on the serum insulin-like growth factor-1 (IGF1), insulin-like growth factor binding protein 3 (IGFBP3), intestinal development, and catch-up growth of intrauterine growth retardation (IUGR) rats by giving the IUGR new born rats different protein level diet. Methods IUGR rat model was built by starvation of pregnant female rats. Twenty-four IUGR pups and 8 normal pups were divided randomly into 4 groups: normal control group (C group); IUGR control group(S group), IUGR low-protein diet group (SL group), and IUGR high-protein diet group (SH group). Detected the serum IGF1, IGFBP3, body weight, body length, intestinal weight length, intestinal villi height (VH), crypt depth (CD), villi absorbing area (VSA), mucous thickness (MT), and disaccharidase at the 4th week. Results (1) The SH group showed the fastest catch-up growth, serum IGF1, IGFBP3, VH, and VSA were significantly higher than those of normal control group and IUGR control group. The intestinal weight and length, and the activities of lactase and saccharase, of the SH group also reached the normal control group level. (2) The SL group kept on small size, the serum IGF-1, IGFBP3, and most of intestinal histological indexes were all significantly lower than other groups. (3) IGF-1, IGFBP3 were positively correlated to intestinal VH, VSA, saccharase, body weight and length. Conclusions The serum IGF1 was a sensitive index to the catch-up growth. The early nutritional intervention of high-protein diet after birth is helpful for the catch-up growth of IUGR through promoting the intestinal development and the absorption of nutrition. [ABSTRACT FROM AUTHOR]