Overexpression of Smac/DIABLO in Hep-2 cell line: possible role in potentiating the sensitivity of chemotherapeutic drugs.
OBJECTIVE
The major obstacles for tumor chemotherapy are drug resistance and/or adverse effects on the host. In the present study we investigated the role of the second mitochondria-derived activator of caspase (Smac/DIABLO) in the action of cisplatin (DDP), 5-fluorouracil (5-FU), and the combination of both in Hep-2 cells.


METHODS
Hep-2 laryngeal carcinoma cells exposed to DDP, 5-FU and the combination of both were investigated. Cell viability was determined by MTT assay. Apoptosis was measured by Ho.33342 and PI double staining and flow cytometry. The expression of Smac/DIABLO at the mRNA and protein level was assayed by RT-PCR and Western blotting.


RESULTS
DDP, 5-FU and the combination of both drugs reduced the cell survival rates in a concentration- and time-dependent manner. The drug combination not only exerted a stronger inhibitory effect, but also at a lower concentration compared with the single drugs. Apoptosis was concomitant in a caspase-dependent manner. The expression of Smac/DIABLO increased significantly at both mRNA and protein levels after cell exposure to the combination compared with single drugs.


CONCLUSIONS
Smac/DIABLO plays a pivotal role in attaining a synergistic effect in Hep-2 cells in response to this combined strategy.
Lu
Sumei
S
Institute of Eye and ENT Provincial Hospital affiliated to Shandong University, Jinan, PR China.
Xu
Wei
W
Fan
Zhaomin
Z
Liu
Wenwen
W
Li
Jianfeng
J
Wang
Haibo
H
D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3 / Q000032:analysis; D053453:Caspase 9 / Q000032:analysis; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D005434:Flow Cytometry; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D007822:Laryngeal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D024101:Mitochondrial Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
D051017:Apoptosis Regulatory Proteins; C412403:DIABLO protein, human; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D053148:Caspase 3; D053453:Caspase 9; D002945:Cisplatin; D005472:Fluorouracil