Arctigenin inhibits proliferation of ER-positive breast cancer cells through cell cycle arrest mediated by GSK3-dependent cyclin D1 degradation

Estrogen receptor (ER) positive accounts for a large proportion of breast cancer. Although there are many targeted therapeutic drugs, the emergence of drug resistance urgently requires the development of new drugs. Arctigenin (Arc), a lignan found in certain plants of the Asteraceae, has the effect on inhibiting breast cancer, but its molecular mechanism has not been clear.

Aims: To this end, the current study focuses on understanding the mechanism of Arc on ER-positive breast cancer cells.

Main methods: Colony formation experiments and sulforhodamine B methods were used to determine the growth-inhibitory effect of Arc. The cell cycle and apoptosis were analyzed by flow cytometry. Alterations of signaling proteins were measured by Western blotting. Protein degradation was determined by comparing protein half-lives and inhibiting proteasome.

Key findings: The experimental results show that Arc did not induce apoptosis in ER-positive breast cancer cell, rather caused G1 cycle arrest by decreasing cyclin D1 levels without effect on altering CDK4/6 levels. Moreover, we have demonstrated that Arc decreases cyclin D1 levels through prompting Akt/GSK3β-mediated degradation.

Significance: These findings warrant the potential of Arc as a candidate treatment for ER-positive breast cancer.