Reprod. Nutr. Dev. 42 (2002) 55-64
DOI: 10.1051/rnd:2002006

Growth and cell cycle regulation by isoflavones in human breast carcinoma cells

Chingwen Ying^a, Jih-Tay Hsu^b, Hsiao-Chiao Hung^a, Don-Hei Lin^a, Long-Fang Oliver Chen^c and Lu-Kai Wang<sup>a

a</sup>  Department of Microbiology, Soochow University, Taipei, Taiwan, Republic of China
^b  Department of Animal Science, National Taiwan University, Taipei, Taiwan, Republic of China
^c  Institute of Botany, Academia Sinica, Taipei, Taiwan, Republic of China

(Received 7 June 2001; accepted 25 January 2002)

Abstract
The isoflavones daidzein and biochanin A induced a biphasic growth response in T-47D human breast cancer cells. At growth stimulatory concentrations, daidzein increased the percentage of cells entering the S phase, while at a growth inhibitory concentration, daidzein obstructed the progression of the cell cycle in the G2/M phase. Biochanin A regulated the cell cycle progression in a similar manner and showed a delay in the progression from the S phase to the G2/M phase at growth inhibitory concentrations. The levels of a cell cycle regulatory protein, P53, in response to the treatment of isoflavones, were also determined. Cells that became de-attached and floated in the medium after treatment with growth inhibitory concentrations of daidzein or biochanin A, showed higher P53 levels than cells that remained attached. These results suggest that daidzein and biochanin A influence T-47D cell proliferation and cell cycle progression, and that the underlying mechanisms might be associated with the P53 protein levels.

Key words: isoflavones / cell cycle / P53 / breast cancer cells

Correspondence and reprints: Chingwen Ying cying@mail.scu.edu.tw

© INRA, EDP Sciences 2002