Anti-proliferative effect in epithelial ovarian cancer cells by MEK Inhibitor AZD6244 / 대한산부인과학회지

OBJECTIVE: The objectives of this study were to determine the efficacy of AZD6244, a potent, selective MEK inhibitor, in epithelial ovarian cancer (EOC) cells and to determine the enhanced cell death by combined treatment of paclitaxel and AZD6244. METHODS: EOC cells were treated with tenfold dilutions of AZD6244 (0.1 to 10 micrometer) for 24, 48 and 72 hours. Cell viability was determined by the CellTiter 96 AQueous One Solution Cell Proliferation Assay. The apoptotic cascade was assessed by Caspase-Glo assays. ERK activation was evaluated by Western blot analyses. Cytokine profiling was performed from culture supernatants using the Luminex 200 system. RESULTS: In vitro cell viability showed that ovarian cancer cells with high p-ERK activities (A2780, R454, 01-28) exhibited significant growth inhibition. Cells with low p-ERK activities (R182, CP70), however, were resistant to AZD6244. Caspase-3 was not activated during AZD6244-induced growth inhibition. AZD6244 significantly inhibited p-ERK1/2 in both cell types regardless of constitutive levels of p-ERK. Proinflammatory cytokines including IL-6, IL-8, MCP-1 and GM-CSF were significantly decreased. Paclitaxel activated the p-ERK levels in paclitaxel-resistant R182 cells with low basal p-ERK level. MEK inhibition by AZD6244 enhanced paclitaxel-induced apoptosis significantly in R182 cells. CONCLUSION: These results demonstrate that AZD6244 has a potent growth inhibitory effect in ovarian cancer cells with high p-ERK activities. In addition, targeted inhibition of the extracellular signal-regulated kinase pathway with AZD6244 can enhance the anti-tumor efficacy of the cytotoxic paclitaxel.

MyD88 expression and anti-apoptotic signals of paclitaxel in epithelial ovarian cancer cells / 대한산부인과학회지

OBJECTIVE: The objectives of this study was to evaluate the correlation between myeloid differentiation protein 88 (MyD88) expression and paclitaxel effects on epithelial ovarian cancer cells and to evaluate whether paclitaxel had anti-apoptotic signals. METHODS: Epithelial ovarian cancer cells isolated from ascites and established cell lines were treated with increasing concentrations of paclitaxel (0.2 to 20 microM) for 24 and 48 hours and cell viability was determined using the CellTiter 96 AQueous One Solution Cell Proliferation Assay. Cytokine profiling was performed from culture supernatants using the Luminex 200 system. Nuclear factor-kappaB (NF-kappaB) activity was determined using a Luciferase reporter system. Levels of phospho-extracellular signal-regulated kinase (p-ERK) were measured by Western blot analysis. RESULTS: A strong signal for MyD88 expression was observed in R182, 01-19b and SKOV3 cells (MyD88-positive). A2780, R454 and 01-28 cells showed low levels of MyD88 (MyD88-negative). Paclitaxel effectively decreased cell viability in MyD88-negative A2780, R454, 01-28 cells after 24 and 48 hours (57%, 49%, 42% and 35%, 28%, 29%, respectively). MyD88-positive cells were resistant to paclitaxel. There was a significant increase in caspase-3/7 activity following paclitaxel treatment in MyD88-negative cells. No significant change in caspase-3/7 activity was detected in MyD88-positive cells. Paclitaxel induced NF-kappaB activation and enhanced the secretion of interleukin-6 (IL-6) and IL-8 in a dose dependent manner and induced ERK phosphorylation on MyD88-positive cells. CONCLUSION: Paclitaxel treatment for MyD88-positive ovarian cancer could have detrimental effects due to the paclitaxel-induced enhancement of NF-kappaB, ERK activities and pro-inflammatory cytokine production, which promote chemoresistance and tumor progression.