Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10758934 | Biochemical and Biophysical Research Communications | 2013 | 6 Pages |
Abstract
Resistance of estrogen receptor-positive breast cancer cells to tamoxifen represents a major barrier to the successful treatment of breast cancer. In the present study, we found that vacuolar H+ ATPase (vATPase) inhibitors, bafilomycin A1 and concanamycin A, sensitize tamoxifen-induced cell death. siRNA targeting ATP6V0C, a 16-kDa hydrophobic proteolipid subunit of vATPase that plays a central role in H+ transport, markedly increased cell death induced by tamoxifen. Interestingly, bafilomycin A1 induced up-regulation of DR4/DR5 and CHOP. Knock-down of CHOP by siRNA suppressed the cell death induced by bafilomycin A1 and tamoxifen, suggesting that bafilomycin A1-mediated CHOP activation sensitizes to tamoxifen. In addition, we found that bafilomycin A1 enhances TRAIL-induced cell death in breast cancer cells. Furthermore, we showed that combination of vATPase inhibitors with tamoxifen also effectively induced cell death in HER2- and ERα-overexpressing breast cancer cells. Overall, our results demonstrate that inhibition of vATPase can potentiate the apoptotic effects of tamoxifen through up-regulation of CHOP.
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Authors
Hyeon-Ok Jin, Yun-Han Lee, Hyun-Ah Kim, Eun-Kyu Kim, Woo Chul Noh, Young-Sun Kim, Chang-Sun Hwang, Jong-Il Kim, Yoon Hwan Chang, Seok-Il Hong, Young-Jun Hong, In-Chul Park, Jin Kyung Lee,