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  • American Association for Cancer Research (AACR)  (4)
  • 1
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 74, No. 22 ( 2014-11-15), p. 6531-6541
    Abstract: Osteosarcoma is a malignant bone tumor in children and adolescents characterized by intrinsic therapeutic resistance. The IGF2 is expressed at elevated levels in osteosarcoma after treatment with chemotherapy, prompting an examination of its functional contributions to resistance. We found that continuous exposure to IGF2 or insulin in the absence of serum created a dormant growth state in osteosarcoma cells that conferred resistance to various chemotherapeutic drugs in vitro. Mechanistic investigations revealed that this dormant state correlated with downregulation of downstream signaling by the IGF1 receptor, heightened cell survival, enhanced autophagy, and the presence of extracellular glutamine. Notably, inhibiting autophagy or depleting glutamine was sufficient to increase chemotherapeutic sensitivity in osteosarcoma xenografts in mice. Clinically, we confirmed that IGF expression levels were elevated in human osteosarcoma specimens from patients who received chemotherapy. Together, our results suggest that activation of IGF or insulin signaling preserves the survival of osteosarcoma cells under chemotherapeutic stress, providing a drug-resistant population that may engender minimal residual disease. Attenuating this survival mechanism may help overcome therapeutic resistance in osteosarcoma. Cancer Res; 74(22); 6531–41. ©2014 AACR.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2014
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    detail.hit.zdb_id: 410466-3
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  • 2
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2010
    In:  Cancer Research Vol. 70, No. 8_Supplement ( 2010-04-15), p. 5164-5164
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 70, No. 8_Supplement ( 2010-04-15), p. 5164-5164
    Abstract: Cancer stem cells (CSCs) are a subset of tumor cells that are responsible for initiating and maintaining the disease. However, the genetic changes and cellular context determining those characteristics of CSCs remain unclear. In addition, what differentiation properties are suitable or refractory to the generation of CSCs is still unknown. To address these questions, we attempted to establish CSCs from normal tissues. As the target tissue of tumorigenesis, we chose mouse bone marrow stromal cells (BMSCs), which comprise of various mesenchymal lineages at different maturation stages derived from mesenchymal stem cells (MSCs). By overexpressing c-MYC in BMSCs derived from Ink4a/Arf (−/−) mice, we generated mouse osteosarcoma (OS) CSC in vitro. The inoculation of the established cells resulted in lethal OS in C57BL/6 syngeneic mice. To clarify the cells of origin of OS, we performed single cell cloning. According to differentiation potentials, those c-MYC expressing BMSCs were composed of two distinctly-different clones: bipotent (osteogenic and chondrogenic) cells designated AX cells and tripotent (adipogenic, osteogenic, and chondrogenic) cells termed AO cells. Their differentiation potentials and gene expression profiling suggested that AX cells were derived from osteo-chondro-committed progenitor cells, while AO cells were originated from MSCs. Bipotent AX cells were highly tumorigenic and possessed high propensity for distant metastasis that mimics human disease. In addition, they showed both terminal differentiation and self-renewal capacity in vivo, which are properties ascribed to CSC. Notably, tripotent AO cells also developed lethal OS in syngeneic mice more slowly and less frequently than AX cells. Moreover, during OS development tripotent AO cells lost their adipogenic potential and transformed into AX-like cells in vivo. Thus, the loss of adipogenic potential was suggested to be an essential event for OS development. To confirm this notion, we shifted the mesenchymal differentiation property by depletion and overexpression of PPARγ in tripotent AO and bipotent AX cells, respectively. The PPARγ knockdown afforded tripotent AO cells the advantage to OS formation in both differentiation and proliferation. In contrast, overexpression of PPARγ in bipotent AX cells attenuated their OS CSC activities. Therefore, our findings indicated that differentiation potentials played key roles on the tumor initiating activity and lineage commitment to osteocyte might be a critical factor for the induction of OS CSC. Our induced OS CSC mouse model was useful for both basic and clinical research to develop novel therapeutic approaches. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5164.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2010
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    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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  • 3
    In: Molecular Cancer Research, American Association for Cancer Research (AACR), Vol. 10, No. 3 ( 2012-03-01), p. 454-468
    Abstract: Osteosarcoma is the most frequent, nonhematopoietic, primary malignant tumor of bone. Histopathologically, osteosarcoma is characterized by complex mixtures of different cell types with bone formation. The role of environmental factors in the formation of such a complicated tissue structure as osteosarcoma remains to be elucidated. Here, a newly established murine osteosarcoma model was used to clarify the roles of environmental factors such as fibroblast growth factor-2 (Fgf2) or leukemia-inhibitory factor (Lif) in the maintenance of osteosarcoma cells in an immature state. These factors were highly expressed in tumor environmental stromal cells, rather than in osteosarcoma cells, and they potently suppressed osteogenic differentiation of osteosarcoma cells in vitro and in vivo. Further investigation revealed that the hyperactivation of extracellular signal–regulated kinase (Erk)1/2 induced by these factors affected in the process of osteosarcoma differentiation. In addition, Fgf2 enhanced both proliferation and migratory activity of osteosarcoma cells and modulated the sensitivity of cells to an anticancer drug. The results of the present study suggest that the histology of osteosarcoma tumors which consist of immature tumor cells and pathologic bone formations could be generated dependent on the distribution of such environmental factors. The combined blockade of the signaling pathways of several growth factors, including Fgf2, might be useful in controlling the aggressiveness of osteosarcoma. Mol Cancer Res; 10(3); 454–68. ©2012 AACR.
    Type of Medium: Online Resource
    ISSN: 1541-7786 , 1557-3125
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2012
    detail.hit.zdb_id: 2097884-4
    SSG: 12
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  • 4
    In: Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 13, No. 15 ( 2007-08-01), p. 4575-4582
    Abstract: Purpose: The aim of this study was to evaluate the antileukemia activity of a novel FLT3 kinase inhibitor, FI-700. Experimental Design: The antileukemia activity of FI-700 was evaluated in human leukemia cell lines, mutant or wild-type (Wt)-FLT3–expressing mouse myeloid precursor cell line, 32D and primary acute myeloid leukemia cells, and in xenograft or syngeneic mouse leukemia models. Results: FI-700 showed a potent IC50 value against FLT3 kinase at 20 nmol/L in an in vitro kinase assay. FI-700 showed selective growth inhibition against mutant FLT3-expressing leukemia cell lines and primary acute myeloid leukemia cells, whereas it did not affect the FLT3 ligand (FL)–driven growth of Wt-FLT3–expressing cells. These antileukemia activities were induced by the significant dephosphorylations of mutant FLT3 and STAT5, which resulted in G1 arrest of the cell cycle. Oral administration of FI-700 induced the regression of tumors in a s.c. tumor xenograft model and increased the survival of mice in an i.v. transplanted model. Furthermore, FI-700 treatment eradicated FLT3/ITD-expressing leukemia cells, both in the peripheral blood and in the bone marrow. In this experiment, the depletion of FLT3/ITD-expressing cells by FI-700 was more significant than that of Ara-C, whereas bone marrow suppression by FI-700 was lower than that by Ara-C. Conclusions: FI-700 is a novel and potent FLT3 inhibitor with promising antileukemia activity.
    Type of Medium: Online Resource
    ISSN: 1078-0432 , 1557-3265
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2007
    detail.hit.zdb_id: 1225457-5
    detail.hit.zdb_id: 2036787-9
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