Fisetin induces G2/M phase cell cycle arrest by inactivating cdc25C-cdc2 via ATM-Chk1/2 activation in human endometrial cancer cells

Zan-Ying Wang,Wen-Qiong Liu,Zeng-Tao Wei,Si’E Wang

doi:10.3329/bjp.v10i2.21945

Abstract

Endometrial cancer is one of the most prevalent gynaecological malignancies where, currently available therapeutic options remain limited. Recently phytochemicals are exploited for their efficiency in cancer therapy. The present study investigates the anti-proliferative effect of fisetin, a flavonoid on human endometrial cancer cells (KLE and Hec1 A). Fisetin (20-100 µM) effectively reduced the viability of Hec1 A and KLE cells and potentially altered the cell population at G2/M stage. Expression levels of the cell cycle proteins (cyclin B1, p-Cdc2, p-Cdc25C, p-Chk1, Chk2, p-ATM, cyclin B1, H2AX, p21 and p27) were analyzed. Fisetin suppressed cyclin B1 expression and caused inactiva-tion of Cdc25C and Cdc2 by increasing their phosphorylation levels and further activated ATM, Chk1 and Chk2. Increased levels of p21 and p27 were observed as well. These results suggest that fisetin induced G2/M cell cycle arrest via inactivating Cdc25c and Cdc2 through activation of ATM, Chk1 and Chk2.

Highlights

Endometrial cancer is one of the most prevailing gynecological malignancies with increasing incidence (Leslie et al, 2012) and with limited therapeutic options available for advanced and recurrent cancers.Dysregulation of the cell cycle is the most frequent alterations in tumor development (Collins et al, 1997; Hajduch et al, 1999; Buolamwini, 2000)
We investigated whether exposure to fisetin at 20-100 μM for 12 hours affected the expression of cyclin B1 and Cdc2 in cancer cells
Fisetin induced marked elevations in the phophorylated forms of Cdc25C which could have caused raised p-Cdc2 levels leading to their inactivation and cell cycle arrest

Summary

Introduction

Dysregulation of the cell cycle is the most frequent alterations in tumor development (Collins et al, 1997; Hajduch et al, 1999; Buolamwini, 2000). DNA damage sensor, ataxia telangiectasia mutated (ATM) controls cell cycle arrest at G1 and G2 and blocks DNA synthesis that is in progress. ATM phosphorylates Chk on threonine 68 (Thr 68) and Chk on serine 317 and 345 (Ser 317 and Ser 345), causing their activation (Matsuoka et al, 1998; Melchionna et al, 2000). In response to DNA damage and DNA replication stress, Chk and Chk phosphorylate Cdc25C phosphatase, an activator of cyclin dependent kinase, Cdc (Bulavin et al, 2003)

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Conclusion