Objective: To investigate the molecular mechanism of arsenic trioxide(ATO) inhibiting K562 cell proliferation, and explore the new targets for treating chronic myeloid leukemia(CML).

Methods: human CML cell line K562 cells were cultured in vitro, and were treated with different concentrations of ATO; MTT was used to detect the cell proliferation; flow cytometry(FCM) was used to determine cell apoptosis, cell cycle and the expression of CD44; Transcriptional levels of β-catenin and cyclin D1 were assayed by RT-PCR.

Results: 2 µmol/L ATO could inhibit the cell proliferation obviously in a time-and-dose-dependent manner. With drug concentration increasing and time prolonging, the expression rate of CD44 was declined gradrually. FCM with AnnexinV/PI double staining showed that K562 cells were induced to apoptosis after exposure to 2.5-10 µmol/L ATO for 48 hours and in dose-dependent manner. Treating with different concentration ATO for 48 hours, cell ratio of G0/G1 phase increased and cell ratio in S phase decreased gradually. RT-PCR showed that the expression of β-catenin and CyclinD1 decreased with increasing of drug concentration.

Conclusions: ATO in certain concentration range can inhibit K562 cell proliferation, and induce the cell apotosis, the mechanismin influencing the Wnt/β-catenin pathway may be the downregulation of CD44 expression, arresting K562 cells in G0/G1 phase, and affecting the gene transcription, thus inhibiting K562 cell proliferation.