Gliotoxin enhances antitumor activity of endoplasmic reticulum stress inducer-tunicamycin / 中国药学杂志

ABSTRACT

OBJECTIVE: To investigate whether the proteasome inhibitor, gliotoxin, combined with the endoplasmic reticulum stress inducer, tunicamycin, could enhance the apoptotic death of tumor cells. METHODS: MTT assay was used to detect the cytotoxicity. The combined drug index (CDI) was used to evaluate the synergistic effect. Flow cytometry was used to analyze the apoptosis rate. The protein expression level was detected by Western blot. RESULTS: The IC50 of gliotoxin and tunicamycin is (1.44±0.23) and (26.14±6.14) μmol·L-1, respectively. In the effective concentration, gliotoxin combined with tunicamycin could significantly inhibit cell proliferation and induce typical apoptotic morphological changes. The combination was synergistic according to the result of MTT assay. As measured by flow cytometry, the combination remarkably increased the apoptosis rates of HT-1080 cells, especially for 0.2 μmol·L-1 gliotoxin combined with tunicamycin, the apoptosis rate was up to 66.6% and CDI was 0.649. The expression changes of apoptosis-related proteins such as caspase-8, caspase-3, PARP and NF-kB were detected when treated with the combination. CONCLUSION: Gliotoxin can improve the chemosensitivity of fibrosarcoma HT-1080 cells to tunicamycin and enhance the apoptosis of tumor cells induced by tunicamycin. Thus, our study may provide a new drug combination to antitumor therapy.