[Proteasome inhibitors sensitize ovarian cancer cells to cisplatin].

OBJECTIVE

To explore the sensitivity and the molecular mechanism of cisplatin-resistance ovarian cancer cell line C13 to proteasome inhibitors and the combination with cisplatin.

METHODS

After different treatments, methyl thiazolyl tetrazolium (MTT) assay was applied to examine the cell viability, annexin-V/propidium iodide (PI) apoptosis detection kit was used to determine the apoptosis rate of different groups, western blot assay was introduced to evaluate the expression levels of Fas-associated death domain-like interleukin-1 beta converting enzyme inhibitory protein (cFLIPs), and the activity of caspase-8 was examined.

RESULTS

MTT assay shown that the cell viability ratios of combination group at serial time points from 12, 24, 36, 48, 60, 72 hours were (56.0 ± 8.4) %, (44.7 ± 7.3) %, (33.7 ± 11.2) %, (27.6 ± 8.0) %, (27.6 ± 7.6) % and (28.1 ± 2.4) %, which were much lower than those of cisplatin group (P < 0.05). After treated for 24 hours, apoptosis rates of cisplatin group, bortezomib group and combination group were (16.7 ± 1.7) %, (23.4 ± 2.1) % and (26.9 ± 1.6) %, respectively. The rate of combination group was much higher than that of non-treated group and that of cisplatin group or bortezomib group (P < 0.05). Western blot assay showed the changes of expression levels of cFLIPs, which were down-regulated seriously after cisplatin, bortezomib or combination treatment [(43.2 ± 2.3) % vs (75.7 ± 3.0) % vs (67.9 ± 2.1) %, P < 0.05]. The caspase-8 activity of combination group was (5.6 ± 1.6) folds than that of non-treated group, which was higher than those of other two groups [(2.3 ± 1.0) and (4.2 ± 0.9) folds, P < 0.05].

CONCLUSIONS

The tumor cell lethal effect of cisplatin could be increase significantly by the combination application of proteasome inhibitors, bortezomib. And the cFLIPs/caspase-8 signaling pathway may be play an important role in the molecular mechanism of the combination treatment.