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TRAIL Resistance of Breast Cancer Cells Is Associated with Constitutive Endocytosis of Death Receptors 4 and 5
Ist Teil von
Molecular cancer research, 2008-12, Vol.6 (12), p.1861-1871
Ort / Verlag
United States: American Association for Cancer Research
Erscheinungsjahr
2008
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its agnostic antibodies, which are being evaluated clinically
as anticancer therapies, selectively kill cancer cells through the death receptors DR4 and DR5. However, their therapeutic
potential is limited by occurring resistance in tumor cells. Here, we compared the apoptotic response of a panel of six human
breast cancer cell lines with recombinant human TRAIL and antibodies to DR4 or DR5. Despite their total mRNA and protein expression,
TRAIL death receptors, with a higher frequency in DR4, are absent on cell surface in some cell lines. Loss of cell surface
expression of DR4 or DR5 accounts for resistance to their corresponding antibody and, importantly, correlates with a decreased
sensitivity to TRAIL. TRAIL resistance occurs when both receptors are absent on cell surface regardless of alterations in
Bcl-2 family proteins or caspases. Furthermore, inhibition of endocytosis by pharmacologic inhibitors or disruption of clathrin-dependent
endocytosis signaling components (adaptor protein 2 and clathrin) restores cell surface expression of the death receptors
and sensitize TRAIL-resistant cells to TRAIL-induced apoptosis. DR4 endocytosis appears to be mediated by its cytoplasmic
domain EAQC 337 LL. The results show that TRAIL death receptors undergo constitutive endocytosis in some breast cancer cells. Loss of cell
surface expression of DR4 and DR5 could be evaluated as a biomarker for TRAIL resistance in breast tumors. Moreover, the clathrin-mediated
endocytosis pathway could be a potential target for therapeutics to overcome tumor resistance to TRAIL receptor-targeted therapies.
(Mol Cancer Res 2008;6(12):1861–71)