Icariin and icaritin stimulate the proliferation of SKBr3 cells through the GPER1-mediated modulation of the EGFR-MAPK signaling pathway.
Icariin (ICA) and icaritin (ICT), with a similar structure to genistein, are the important bioactive components of the genus Epimedium, and regulate many cellular processes. In the present study, using the estrogen receptor (ER)-negative breast cancer cell line, SKBr3, as a model, we examined the hypothesis that ICA and ICT at low concentrations stimulate SKBr3 cell proliferation in vitro through the functional membrane, G protein‑coupled estrogen receptor 1 (GPER1), mediated by the epithelial growth factor receptor (EGFR)‑mitogen-activated protein kinase (MAPK) signaling pathway. MTT assay revealed that ICA and ICT at doses of 1 nM to 1 µM markedly stimulated SKBr3 cell proliferation in a dose-dependent manner. The ICA- and ICT-stimulated cell growth was completely suppressed by the GPER1 antagonist, G-15, indicating that the ICA‑ and ICT-stimulated cell proliferation was mediated by GPER1 activation. Semi-quantitative RT-PCR analysis revealed that treatment with ICA and ICT enhanced the transcription of c-fos, a proliferation-related early gene. The ICA- and ICT-stimulated mRNA expression was markedly attenuated by G-15, AG-1478 (an EGFR antagonist) or PD98059 (a MAPK inhibitor). Our data also demonstrated that ICA and ICT increased the phosphorylation of ERK1/2. The ICA- and ICT-stimulated ERK1/2 phosphorylation was blocked by pre-treatment of the cells with G-15 and AG-1478 or PD 98059. Flow cytometric analysis confirmed that the ICA- and ICT-stimulated SKBr3 cell proliferation involved the GPER1-mediated modulation of the EGFR‑MAPK signaling pathway. To the best of our knowledge, our current findings demonstrate for the first time that ICA and ICT promote the progression of ER-negative breast cancer through the activation of membrane GPER1.
The Key Laboratory of Plant Resources and Chemistry of Arid Zone, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011, P.R. China.
Hai-Rong
HR
Ma
Key Laboratory of Xinjiang Endemic Phytomedicine Resources, Ministry of Education, College of Pharmacy, Shihezi University, Shihezi 832002, P.R. China.
Jie
J
Wang
Vascular Biology and Hypertension Program, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Yiu-Fai
YF
Chen
The Key Laboratory of Plant Resources and Chemistry of Arid Zone, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011, P.R. China.
Hua
H
Chen
School of Medicine, Shihezi University, Shihezi 832002, P.R. China.
Wei-Shan
WS
Wang
The State Key Laboratory Basis of Xinjiang Indigenous Medicinal Plants Resource Utilization, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011, P.R. China.
Haji Akber
HA
Aisa
D000818:Animals; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000502:physiology; D005419:Flavonoids / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000235:genetics / Q000502:physiology; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*
D005419:Flavonoids; C109584:GPER1 protein, human; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; C499403:icaritin; C056599:icariin