TY - JOUR
T1 - EZH2 inhibition decreases p38 signaling and suppresses breast cancer motility and metastasis
AU - Moore, Heather M.
AU - Gonzalez, Maria E.
AU - Toy, Kathy A.
AU - Cimino-Mathews, Ashley
AU - Argani, Pedram
AU - Kleer, Celina G.
N1 - Funding Information:
Acknowledgments We thank Xin Li for help in mouse colony maintenance and executing the spontaneous metastasis assay. We thank Wei Huang and Paul Moore for helpful experimental suggestions and support. We thank Yali Dou and Bo Zhou for assistance with the in vitro methylation assay. This study was supported by the Department of Defense Breast Cancer Research Program through a Predoctoral Traineeship Award (BC093828; to H. M. M) and the National Institutes of Health Grants R01 CA107469, R01 CA125577 and U01 CA154224 (to C. G. K.), and the University of Michigan’s Cancer Center Support Grant (5 P30 CA46592).
PY - 2013/4
Y1 - 2013/4
N2 - EZH2 is a Polycomb group protein that exerts oncogenic functions in breast cancer, where its overexpression is associated with metastatic disease. While it reportedly acts a transcriptional repressor through trimethylation of histone H3 at lysine 27, EZH2 may exhibit context-dependent activating functions. Despite associations with worse outcome and metastasis in breast cancer, a functional role of EZH2 in breast cancer metastasis in vivo has not been demonstrated. Furthermore, whether EZH2 regulates cancer cell phenotype and motility are unknown. In this study, we discovered that knockdown of EZH2 induces a phenotypic reprogramming from mesenchymal to epithelial, reduces motility, and blocks invasion in breast cancer cell lines. In vivo, EZH2 downregulation in MDA-MB-231 cells decreases spontaneous metastasis to the lungs. We uncover an unexpected role of EZH2 in inducing the p38 mitogen-activated protein kinase signaling pathway, an important regulator of breast cancer invasion and metastasis. In breast cancer cells, EZH2 binds to phosphorylated p38 (p-p38) in association with other core members of the Polycomb repressive complex 2, EED, and SUZ12, and EZH2 overexpression leads to increased levels of p-p38 and of activated, downstream pathway proteins. The effect on p-p38 was confirmed in vivo, where it correlated with decreased spontaneous metastasis. In clinical specimens of matched primary and invasive breast carcinomas, we found that EZH2 expression was upregulated in 100 % of the metastases, and that EZH2 and p-p38 were coexpressed in 63 % of cases, consistent with the functional results. Together our findings reveal a new mechanism by which EZH2 functions in breast cancer, and provide direct evidence that EZH2 inhibition reduces breast cancer metastasis in vivo.
AB - EZH2 is a Polycomb group protein that exerts oncogenic functions in breast cancer, where its overexpression is associated with metastatic disease. While it reportedly acts a transcriptional repressor through trimethylation of histone H3 at lysine 27, EZH2 may exhibit context-dependent activating functions. Despite associations with worse outcome and metastasis in breast cancer, a functional role of EZH2 in breast cancer metastasis in vivo has not been demonstrated. Furthermore, whether EZH2 regulates cancer cell phenotype and motility are unknown. In this study, we discovered that knockdown of EZH2 induces a phenotypic reprogramming from mesenchymal to epithelial, reduces motility, and blocks invasion in breast cancer cell lines. In vivo, EZH2 downregulation in MDA-MB-231 cells decreases spontaneous metastasis to the lungs. We uncover an unexpected role of EZH2 in inducing the p38 mitogen-activated protein kinase signaling pathway, an important regulator of breast cancer invasion and metastasis. In breast cancer cells, EZH2 binds to phosphorylated p38 (p-p38) in association with other core members of the Polycomb repressive complex 2, EED, and SUZ12, and EZH2 overexpression leads to increased levels of p-p38 and of activated, downstream pathway proteins. The effect on p-p38 was confirmed in vivo, where it correlated with decreased spontaneous metastasis. In clinical specimens of matched primary and invasive breast carcinomas, we found that EZH2 expression was upregulated in 100 % of the metastases, and that EZH2 and p-p38 were coexpressed in 63 % of cases, consistent with the functional results. Together our findings reveal a new mechanism by which EZH2 functions in breast cancer, and provide direct evidence that EZH2 inhibition reduces breast cancer metastasis in vivo.
KW - Breast cancer
KW - Cell motility
KW - EZH2
KW - Metastasis
KW - Snail
KW - p38
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UR - http://www.scopus.com/inward/citedby.url?scp=84877836496&partnerID=8YFLogxK
U2 - 10.1007/s10549-013-2498-x
DO - 10.1007/s10549-013-2498-x
M3 - Article
C2 - 23539298
AN - SCOPUS:84877836496
SN - 0167-6806
VL - 138
SP - 741
EP - 752
JO - Breast Cancer Research and Treatment
JF - Breast Cancer Research and Treatment
IS - 3
ER -