Related Experiment Video
Updated: Apr 4, 2026
Molecular Analysis of Endothelial-mesenchymal Transition Induced by Transforming Growth Factor-β Signaling
Published on: August 3, 2018
Mitogen-activated protein kinase phosphatase 1 is involved in tamoxifen resistance in MCF7 cells
Gang Ma1, Yixia Pan2, Can Zhou1
1Department of Breast Surgery, The First Affiliated Hospital, Medicine College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China.
Abstract:
Tamoxifen resistance is a major clinical problem for ER-positive breast cancer, but the underlying mechanism is not completely elucidated. In the present study, we reported that mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1), a member of the family of MKPs, is involved in tamoxifen resistance. We found that MKP1 expression increased in tamoxifen resistant MCF7 cells. To explore the possible role of MKP1 in tamoxifen resistance, siRNA targeting MKP1 was transfected into tamoxifen resistant MCF7 cells. To our surprise, knockdown of MKP-1 promoted cell death induced by tamoxifen. On the other hand, the MKP1 overexpressed MCF7 cell clone was established and MKP1 overexpression effectively attenuated MCF7 cell death induced by tamoxifen. In addition, we revealed that MKP1 inhibited tamoxifen‑mediated JNK activation in tamoxifen resistant MCF7 and MCF7 cells, and by this mechanism MKP1 was able to inhibit tamoxifen-induced cell death. We also showed that combined appliaction of MKP1 inhibitor triptolide and tamoxifen can effectively increase tamoxifen sensitivity in tamoxifen resistant MCF7 cells. Collectively, our results indicated that MKP-1 can attenuate tamoxifen-induced cell death through inhibiting the JNK signal pathway, which represents a novel mechanism of tamoxifen resistance in MCF7 cells.
Insights
Mitogen-activated protein kinase phosphatase 1 (MKP-1) promotes tamoxifen resistance in ER-positive breast cancer by inhibiting JNK activation. Inhibiting MKP-1 enhances tamoxifen sensitivity, offering a new therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Tamoxifen resistance is a significant clinical challenge in estrogen receptor-positive breast cancer.
- The precise molecular mechanisms underlying tamoxifen resistance remain incompletely understood.
Purpose of the Study:
- To investigate the role of mitogen-activated protein kinase phosphatase 1 (MKP-1) in tamoxifen resistance in MCF7 breast cancer cells.
- To elucidate the mechanism by which MKP-1 influences tamoxifen sensitivity and cell death.
Main Methods:
- Utilized siRNA to knockdown MKP-1 expression in tamoxifen-resistant MCF7 cells.
- Established MCF7 cell clones overexpressing MKP-1.
- Assessed tamoxifen-induced cell death and JNK pathway activation.
- Investigated the effect of combined MKP-1 inhibitor (triptolide) and tamoxifen treatment.
Main Results:
- MKP-1 expression was elevated in tamoxifen-resistant MCF7 cells.
- MKP-1 knockdown sensitized cells to tamoxifen-induced death, while overexpression conferred resistance.
- MKP-1 inhibited tamoxifen-mediated JNK activation.
- Combined triptolide and tamoxifen treatment increased tamoxifen sensitivity in resistant cells.
Conclusions:
- MKP-1 attenuates tamoxifen-induced cell death by suppressing the JNK signaling pathway.
- This represents a novel mechanism contributing to tamoxifen resistance in MCF7 breast cancer cells.
- Targeting MKP-1 may represent a viable strategy to overcome tamoxifen resistance.
