Research Area
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Description
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Cancer |
Biological Activity
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Description
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Fludarabine (Fludara, F-ara-A, NSC 118218) is a STAT1 activation inhibitor and a DNA synthesis inhibitor. |
Targets
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IC50 |
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In Vitro
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Fludarabine efficiently inhibits the proliferation of RPMI 8226 cells with IC50 of 1.54 μg/mL. The IC50 of Fludarabine against MM.1S and MM.1R cells is 13.48 μg/mL and 33.79 μg/mL, respectively. In contrast, U266 cells are resistant to Fludarabine with IC50 of 222.2 μg/mL. Fludarabine treatment results in increased number of cells in the G1 phase of cell cycle, accompanied with a concomitant reduction of cells at the S phase of cell cycle in a time-dependent manner. Fludarabine induces a cell cycle block and triggers apoptosis in MM cells. Fludarabine triggers time-dependent cleavage of caspase-8, -9, and -3, -7, followed by PARP cleavage. Fludarabine increases expression of Bax in a time-dependent fashion, while the expression of Bak doesn’t change. After exposure to Fludarabine for 12 hours, RPMI 8226 cells shows a loss of membrane potential with 61.05% of the cells expressing low fluorescence of rhodamine 123 compared with 8.62% of cells in untreated control. [1] To enhance solubility, Fludarabine is formulated as the monophosphate (F-ara-AMP, fudarabine), which is instantaneously and quantitatively dephosphorylated to the parent nucleoside upon intravenous infusion. Inside the cells rephosphorylation occurs which leads to fuoroadenine arabinoside triphosphate (F-ara-ATP), the major cytotoxic metabolite of F-ara-A. [2] Fludarabine can also induce pro-inflammatory stimulation of monocytic cells, as evaluated by increased expression of ICAM-1 and IL-8 release. [3] Fludarabine does not affect the growth of ovarian cancer cell lines, whereas it induces marked and dose-dependent inhibition of proliferation in melanoma cell lines. [4] Fludarabine induces significant reduction of STAT-1 phosphorylation, whereas it does not change JAK2 activation. Interestingly, Fludarabine does not significantly affect the phosphorylation of these three STAT proteins. Fludarabine (1.5 mg) significantly prevents STAT-1 phosphorylation and also reduces the increased amount of this protein. No significant changes are demonstrated in JAK2 phosphorylation at 2 days, but Fludarabine inhibits JAK2-increased expression at 7 days. Fludarabine specifically inhibits STAT-1 activation without affecting other STAT proteins and consequently diminishes VSMC proliferation. [5] |
In Vivo
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Tumors treated with PBS grow rapidly to approx-imately 10-fold their initial volume in 25 day, whereas, the tumors in the Fludarabine at 40 mg/kg increase less than 5-fold. A significant antitumor effect of 40 mg/kg Fludarabine on RPMI8226 tumor growth is demonstrated. RPMI8226 tumors treated with 40 mg/kg Fludarabine at day 10 increase apoptotic nuclei. Fludarabine is effective in suppressing RPMI8226 myeloma xenografts in SCID mice. [1] |
Clinical Trials
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Features
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Combination Therapy
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Description
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Fludarabine phosphate plus cyclophosphamide and rituximab has entered in a Phase II clinical trial in the treatment of chronic lymphocytic leukemia. |
Protocol
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Cell Assay
[1]
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Cell Lines |
Dexamethasone-sensitive (MM.1S) and -resistant (MM.1R) human MM cell lines, RPMI8226 and U266 cell lines |
Concentrations |
2 μg/mL |
Incubation Time |
24 hours |
Methods |
After treated with Fludarabine or control, dexamethasone-sensitive (MM.1S) and -resistant (MM.1R) human MM cell lines, RPMI8226 and U266 cell lines (5 × 105 cells) are washed twice in phosphate-buffered saline (PBS) and fixed with 70% ice-cold ethanol, then centrifuged and suspended in PBS containing 100 μg/mL RNase A. After incubated for 30 minutes at 37 oC, samples are resuspended in 25 μg/mL propidium iodide. Flow cytometry is performed on a FACSCalibur automated system. Apoptosis is determined by Annexin V-FITC apoptosis detection kit, according to the manufacturer’s instructions. For TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling) assay, cells are analyzed by flow cytometry using the in situ cell death detection kit. |
Animal Study
[1]
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Animal Models |
Severe combined immunodeficient (SCID) mice bearing RPMI 8226 cells |
Formulation |
PBS |
Doses |
40 mg/kg |
Administration |
Administered via i.p. |
References |
[1] Meng H, et al. Eur J Haematol. 2007, 79(6), 486-493.
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[2] Brachwitz H, et al. Bioorg Med Chem. 1999, 7(6), 1195-1200.
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[3] Fernández-Calotti P, et al. Int Immunopharmacol. 2006, 6(5), 715-723.
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[4] Zaffaroni N, et al. Eur J Cancer. 1996, 32A(10), 1766-1773.
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[5] Torella D, et al. Am J Physiol Heart Circ Physiol. 2007, 292(6), H2935-2943.
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