ERK/CANP rapid signaling mediates 17β-estradiol-induced proliferation of human breast cancer cell line MCF-7 cells.
OBJECTIVE
17β-estradiol (E2) exerts its functions through both genomic and non-genomic signaling pathways. Because E2 is important in breast cancer development, we investigated whether its actions in promoting breast cancer cell proliferation occur through the non-genomic signaling pathway via extracellular signal-regulated kinase 1/2 (ERK1/2)/calcium-activated neutral protease (CANP).


METHODS
MCF-7 breast cancer cells were treated with ERKl/2 inhibitor (PD98059) or CANP inhibitor (calpeptin) before exposure to 1×10(-8) M E2. MTT colorimetry and flow cytometry were used to analyze effects on cell proliferation and cell cycle progression, respectively. Expression of phosphorylated-ERK (p-ERK), total ERK, and Capn4 proteins were assessed by Western blotting.


RESULTS
Cell proliferation increased in cells treated with E2 for 24 h (P<0.05), and the proportion of cells in G0/G1 was decreased, accompanied by accelerated G1/S. Calpeptin pre-treatment significantly inhibited the E2-induced proliferation of MCF-7 cells (P<0.05), while also ameliorating the effects of E2 on cell cycle progression. Further, expression of p-ERK was rapidly up-regulated (after 10 min) by E2 (P<0.05), an effect that persisted 16 h after E2 exposure but which was significantly inhibited by PD98059 (P<0.05).


CONCLUSIONS
Finally, expression of Capn4 protein was rapidly up-regulated in E2-exposed cells (P<0.05), but this change was significantly inhibited by PD98059 or calpeptin (P<0.05) pre-treatment. Thus, the rapid, non-genomic ERK/CANP signaling pathway mediates E2-induced proliferation of human breast cancer cells.
The First Affiliated Hospital of Harbin Medical University 23 Youzheng Str, Nangang District, Harbin 150001, Heilongjiang Province, P. R. China.
Guo-Sheng
GS
Wang
The First Affiliated Hospital of Harbin Medical University 23 Youzheng Str, Nangang District, Harbin 150001, Heilongjiang Province, P. R. China.
Yan-Gang
YG
Huang
School of Medicine, Shenzhen University Nanhai Ave 3688, Shenzhen 518060, Guangdong Province, China.
Huan
H
Li
The First Affiliated Hospital of Harbin Medical University 23 Youzheng Str, Nangang District, Harbin 150001, Heilongjiang Province, P. R. China.
Shi-Jie
SJ
Bi
The First Affiliated Hospital of Harbin Medical University 23 Youzheng Str, Nangang District, Harbin 150001, Heilongjiang Province, P. R. China.
Jin-Long
JL
Zhao
Breast cancer cell; cell proliferation; estradiol; extracellular signal-regulated kinase