Acquired TRAIL resistance in human breast cancer cells are caused
by the sustained cFLIPL and XIAP protein levels and ERK activation
- Tae-Jin Lee; Jung Tae Lee; Jong-Wook Park; Taeg Kyu Kwon
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- We established TRAIL-resistant MDA-231/TR cells from MDA-231 parent cells to understand the mechanism of TRAIL resistance in breast cancer cells. The selected TRAIL-resistant cells were cross-resistant to TNF-α/cycloheximide but remained sensitive to DNA-damage drugs such as oxaliplatin and etoposide. The expression levels of death receptors (DR4 and DR5), FADD, cIAP1, cIAP2, and Bcl-2 family were not changed in TRAIL-treated both cells. Significant down-regulation of XIAP and cFLIP was occurred after TRAIL treatment in MDA-231 cells whereas their levels were sustained in MDA-231/TR cells. TRAIL-mediated activation of ERK and JNK were also observed in parent MDA-231 cells but not in MDA-231/TR cells. However, TRAIL-resistant cells showed constitutive activation state after treatment with TRAIL. Pretreatment with PD98059 or transfection of MKK1-DN (dominant negative) expression vector attenuated TRAIL resistance in MDA-231/TR cells. Our findings provide the evidence that the sustained expression level of cFLIPL and XIAP protein and constitutive ERK activation may lead to acquired TRAIL resistance in breast cancer cells.
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