[Synergistic induction of apoptosis by the combination of TRAIL and low dose adriamycin in human osteosarcoma cell line U2OS].
OBJECTIVE
To investigate whether TRAIL can synergize with adriamycin (ADM) to kill osteosarcoma cells (U2OS) in vitro, and its possible molecular mechanism.


METHODS
MTT was used to evaluate the cytotoxic effect of TRAIL and ADM either used alone or in combination at 24 hours after treatment to U20S cells. Cell apoptosis and its proportion were detected by flow cytometry assay. Acridine orange fluorescence microscopy and transmission electron microscopy were used to examine cellular and ultrastructural changes of apoptosis. The changes of cFLIP in mRNA and protein level were semi-quantified by RT-PCR and Western blot analysis.


RESULTS
(1) U2OS cells were not sensitive to TRAIL (IC(50) > 1 mg/L); the cells were relatively more responsive to ADM in an apparent dose-effect fashion. (2) The combination of TRAIL and ADM presented a synergistic effect on U2OS cells. Subtoxic concentration of TRAIL (0.1 mg/L) combined with subtoxic concentration of ADM (1.0 micromol/l) killed (49.54 +/- 2.79)% of U2OS cells. (3) The cytotoxicity was mainly attributed to cell apoptosis as demonstrated by flow cytometry assay, fluorescence microscopy and electron microscopy.


CONCLUSIONS
Subtoxic dose of TRAIL can effectively kill osteosarcoma cells (U2OS) in combination with subtoxic dose of ADM, but not effective when used alone. Apoptosis is the main mechanism of this killing effect induced by combination of TRAIL and ADM. Down regulation of cFLIP at mRNA and protein level is involved in this apoptosis pathway.
Yang
Di-sheng
DS
Department of Orthopaedic Surgery, Second Hospital, Medical College of Zhejiang University, Hangzhou 310009, China.
Miao
Xu-dong
XD
Ye
Zhao-ming
ZM
Xu
Yu-sheng
YS
D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000494:pharmacology*; D001859:Bone Neoplasms / Q000473:pathology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D061945:Caspase Inhibitors; D004317:Doxorubicin / Q000494:pharmacology*; D004357:Drug Synergism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D012516:Osteosarcoma / Q000473:pathology*; D012333:RNA, Messenger / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D061945:Caspase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D004317:Doxorubicin