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ABSTRACT: Heat shock protein 27 (Hsp27), a member of the heat shock protein (Hsp) family, is critical in the regulation of cancer development, progression and chemotherapy resistance. However, the role of Hsp27 in the pathogenesis of pediatric acute leukemia (AL) remains unknown. In this study, we evaluated the expression levels of Hsp27 in bone marrow samples from 94 children with newly diagnosed acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML) and 5 leukemia cell lines. Additionally, we transfected a target-specific siRNA duplex against Hsp27 into leukemia cells, and examined the chemosensitivity and cell apoptosis in the response to antitumor drugs. Hsp27 was abundantly expressed in newly diagnosed AML-M4/M5 bone marrow mononuclear cells (BMMCs) and THP-1, OCI/AML-3 leukemia cell lines. Furthermore, its expression was positively correlated with the clinical status in pediatric M4/M5 subtypes. Knockdown of Hsp27 expression increased the chemosensitivity of leukemia cells and the anticancer drug-induced apoptosis. These results support the theory that Hsp27 plays a contributory role in the pathogenesis of pediatric AML-M4/M5. Therefore, Hsp27 may be exploited as a new target for enhancing the efficacy of chemotherapeutic drugs against leukemia.
Oncology Reports 04/2013; 29(4):1459-66. · 1.84 Impact Factor
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ABSTRACT: IFN1@ (interferon, type 1, cluster, also called IFNα) has been extensively studied as a treatment for patients with chronic myeloid leukemia (CML). The mechanism of anticancer activity of IFN1@ is complex and not well understood. Here, we demonstrate that autophagy, a mechanism of cellular homeostasis for the removal of dysfunctional organelles and proteins, regulates IFN1@-mediated cell death. IFN1@ activated the cellular autophagic machinery in immortalized or primary CML cells. Activation of JAK1-STAT1 and RELA signaling were required for IFN1@-induced expression of BECN1, a key regulator of autophagy. Moreover, pharmacological and genetic inhibition of autophagy enhanced IFN1@-induced apoptosis by activation of the CASP8-BID pathway. Taken together, these findings provide evidence for an important mechanism that links autophagy to immunotherapy in leukemia.
Autophagy 12/2012; 9(3). · 7.45 Impact Factor
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ABSTRACT: Synovial sarcoma is a rare malignant neoplasm that accounts for approximately 6% to 9% of all soft-tissue tumors. It occurs predominately in upper and lower extremities of young adults. We report the first case of a primary orbital synovial sarcoma in an 18-month-old girl.
Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus 11/2012; · 1.07 Impact Factor
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ABSTRACT: microRNAs (miRNAs) are a class of small regulatory RNAs that regulate gene expression at the post-transcriptional level. miRNAs play important roles in the regulation of development, growth, and metastasis of cancer, and in determining the response of tumor cells to anticancer therapy. In recent years, they have also emerged as important regulators of autophagy, a lysosomal-mediated pathway that contributes to degradation of a cell's own components. Imatinib, a targeted competitive inhibitor of the BCR-ABL1 tyrosine kinase, has revolutionized the clinical treatment of chronic myelogenous leukemia (CML). We demonstrate that MIR30A-mediated autophagy enhances imatinib resistance against CML including primary stem and progenitor cells. MIR30A, but not MIR101, is a potent inhibitor of autophagy by selectively downregulating BECN1 and ATG5 expression in CML cells. MIR30A mimics, as well as knockdown of BECN1 and ATG5, increases intrinsic apoptotic pathways. In contrast, the antagomir-30A increases autophagy and inhibits intrinsic apoptotic pathways, confirming that autophagy serves to protect against apoptosis. Taken together, these data clarify some of the underlying molecular mechanisms of tyrosine kinase inhibitor-induced autophagy.
Autophagy 05/2012; 8(5):853-5. · 7.45 Impact Factor
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ABSTRACT: Chemoresistance has become a major obstacle to the successful treatment of leukemia. Autophagy, a regulated process of degradation and recycling of cellular constituents, has recently caught increasing attention for its roles in conferring resistance to various commonly used anticancer therapies. Here we showed that the member of the S100 calcium-binding protein family, S100A8, is a critical regulator of chemoresistance in the autophagy process. It positively correlated with the clinical status in childhood acute myeloblastic leukemia (AML) and it was released from leukemia cells after chemotherapy-induced cytotoxicity. Knockdown of S100A8 expression increased the sensitivity of leukemia cells to chemotherapy and apoptosis. Moreover, suppressing S100A8 expression decreased autophagy as evaluated by the increased expression of the autophagic marker microtubule-associated protein light chain 3 (LC3)-II, degradation of SQSTM1/Sequestosome 1 (p62) and formation of autophagosomes. Furthermore, stimuli that enhanced reactive oxygen species (ROS) promoted cytosolic translocation of S100A8 and thereby enhanced autophagy. S100A8 directly interacted with the autophagy protein Beclin1 displacing Bcl-2. These results suggest that S100A8 is a critical pro-autophagic protein that enhances cell survival and regulates chemoresistance in leukemia cells likely through disassociating the Beclin1-Bcl-2 complex.
International Journal of Molecular Medicine 01/2012; 29(1):65-72. · 1.98 Impact Factor
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Mingyi Zhao,
Minghua Yang, Liangchun Yang,
Yan Yu,
Min Xie,
Shan Zhu,
Rui Kang,
Daolin Tang,
Zhigang Jiang,
Wuzhou Yuan,
Xiushan Wu,
Lizhi Cao
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ABSTRACT: HMGB1 is associated with human cancers and is an activator of autophagy which mediates chemotherapy resistance. We here show that the mRNA levels of HMGB1 are high in leukemia cells and it is involved in the progression of childhood chronic myeloid leukemia (CML). HMGB1 decreases the sensitivity of human myeloid leukemia cells K562 to anti-cancer drug induced death through up-regulating the autophagy pathway, which is confirmed by the observation with an increase in fusion of autophagosomes and autophagolysosomes. When overexpressing HMGB1, both mRNA levels of Beclin-1, VSP34 and UVRAG which are key genes involved in mammalian autophagy and protein levels of p-Bcl-2 and LC3-II are increased. Luciferase assays document that over-expression of HMGB1 increases the transcriptional activity of JNK and ERK, which may be silenced by siRNA. The results suggest that HMGB1 regulates JNK and ERK required for autophagy, which provides a potential drug target for therapeutic interventions in childhood CML.
BMB reports 09/2011; 44(9):601-6. · 1.72 Impact Factor
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Liangchun Yang,
Yan Yu,
Rui Kang,
Minghua Yang,
Min Xie,
Zhuo Wang,
Daolin Tang,
Mingyi Zhao,
Liying Liu,
Hong Zhang,
Lizhi Cao
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ABSTRACT: Autophagy has recently attracted increasing attention for its role in conferring resistance to various commonly used anticancer therapies. Whereas its activities are known primarily to be under regulation of the high mobility group box-1 (HMGB1) gene, the expression of HMGB1 and its function in leukemia cells still remain unclear. In this study, we found that HMGB1 was expressed abundantly in various kinds of both leukemia and non-blood cancer cell-lines, and its expression was positively correlated with clinical status in childhood leukemia. In leukemia cells, when endogenous HMGB1 increased starvation-induced autophagy, this reaction was inhibited by the suppression of HMGB1. While the use of autophagy inhibitor, 3-methyladenine (3-MA), blocked the autophagic reaction and increased leukemia cell sensitivity to chemotherapy, enhancing HMGB1 expression decreased this sensitivity. Notably, suppressing HMGB1 expression also increased leukemia cell chemosensitivity. Furthermore, the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin complex 1 (mTORC1) pathway was found to be functionally connected with HMGB1. HMGB1 gene transfection increased the LC3-II level and inhibited phosphorylation of Akt and p70S6K levels. Knockdown of HMGB1 expression blocked the association between mTOR and raptor in the setting of enhanced autophagy. When class I PI3K was inhibited by PI3K-I shRNA, it decreased the PI3K-I expression level. Knockdown of HMGB1 expression had no further effects on LC3-II. These results suggest that endogenous HMGB1 is an intrinsic regulator of autophagy in leukemia cells and it enhances leukemia cell chemoresistance likely through the PI3K/Akt/mTORC1 pathway.
Leukemia & lymphoma 08/2011; 53(2):315-22. · 2.40 Impact Factor
