Publication Date:
2009-11-20
Description:
Abstract 285 Introduction: MCT-1 is an oncogene that has been shown to induce cell proliferation and activate cell survival pathways and is constitutively expressed in the majority of diffuse large B-cell lymphomas (DLBCL). MCT-1 is phosphorylated by the MEK/ERK kinases, which occurs directly upstream of MCT-1; thus MEK/ERK inhibition blocks the phosphorylation and activation of MCT-1. Potent small-molecule inhibitors of MEK have been developed in pre-clinical and clinical studies that have shown the MEK/ERK pathway can be effectively shut down in a highly selective manner. However, the majority of pre-clinical and clinical information regarding MEK inhibitors to date have emerged mainly from solid tumor studies. The study of anti-MEK therapy is largely unexplored in lymphoma. The benzimidazole AZD-6244 (ARRY-142886) is a novel 2nd generation small molecule MEK antagonist being developed for the treatment of cancer. We investigated the activity of AZD-6244 in DLBCL cell lines, primary cells, and an in vivo xenograft model. Methods: DLBCL cell lines (SUDHL4, SUDHL6, OCI-LY3, and OCI-LY19) and primary cells obtained from a patient with relapsed/refractory transformed DLBCL (absolute lymphocyte count 167.3 K/UL, hemoglobin 9.8 gm/dL, and LDH 1,141 Units/L (high normal 195 Units/L)) were incubated with increasing nanomolar concentrations of AZD-6244 (50-400nM) for 24–72 hours (hr). MTT was calculated and apoptosis was determined by fluorescence-activated cell sorting using AnnexinV-FITC/propidium iodide (AnnV+/PI+) staining. Cleaved caspases and phosphorylated ERK (pERK) and MCT-1 (pMCT-1) were assessed through Western blot studies. In vivo studies were performed with mice bearing subcutaneous tumors of SUDHL6 that were randomly divided into control and AZD-6244 groups. SUDHL6 cells (1.2 × 106) were subcutaneously injected into left and right dorsal flanks of 7-week-old female SCID mice. When the tumor reached the size of approximately 60-163mm3, AZD-6244 was administered intraperitoneally every other day at a dose of 1.0 mg/kg body weight for a total of 3 weeks. Results: Time-dependent cytotoxicity was documented in each of the 4 DLBCL cell lines. IC50 at 48 hours in SUDHL4 and OCI-LY3 was 130nM, 240nM in SUDLH6, and 300nM in OCI-LY19. Dose-dependent apoptosis was also seen in all cell lines. Compared with control at 48 hrs, 〉50% AnnV+/PI+ was documented in SUDHL-4 at 200nM and with 300-320nM in the three other cell lines (p75% AnnV+/PI+ (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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