Induction of Cell Cycle Arrest and p21^CIP1/WAF1 Expression in Human Lung Cancer Cells by Isoliquiritigenin

Cancer Letters
Volume 207, Issue 1 , 15 April 2004, Pages 27-35

Tsunehiro Ii ^a, Yoshiko Satomi ^b, Daishiro Katoh ^a, Junichi Shimada ^a, Masaki Baba ^c, Toru Okuyama ^c, Hoyoku Nishino ^b and Nobuo Kitamura ^a
a Department of Cardiovascular and Thoracic Surgery, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602-8566, Japan
^b Department of Biochemistry and Molecular Biology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kyoto 602-8566, Japan
^c Department of Natural Medicine and Phytochemistry, Meiji Pharmaceutical University, Kawaramachi-Hirokoji, Kyoto 602-8566, Japan

Isoliquiritigenin is a natural flavonoid isolated from licorice, shallot and bean sprouts. The effect of isoliquiritigenin on cell proliferation and cell cycle progression was examined in the A549 human lung cancer cell line. Isoliquiritigenin significantly inhibited the proliferation of lung cancer cells in a dose- and time-dependent manner. Flow cytometric analysis demonstrated that isoliquiritigenin restrained the cell cycle progression at G2/M phase. Further examinations using cDNA arrays and real-time quantitative RT-PCR revealed that isoliquiritigenin enhanced the expression of p21^CIP1/WAF1, a universal inhibitor of cyclin-dependent kinases. These results suggest that isoliquiritigenin will be a promising agent for use in chemopreventive or therapeutics against lung cancer.