Sorting, identification and enrichment of side population cells in acute monocytic leukemia THP-1 Cells

Abstract

Objective To assay and determine whether the human acute monocytic leukemia cell line THP-1 contains side populations (SP) cells, and to increase the proportion of SP cells using cytarabine (Ara-C). Methods Fluorescent microscope and flow cytometry (FCM) were employed for detecting the percentage of SP cells in THP-1 cells.Then, SP and non-SP (NSP) subpopulations were collected and identified.Finally, THP-1 cells were incubated with different concentrations of Ara-C for 24 hours and detected the proportion of SP cells, respectively. Results The results demonstrated that the percentage of SP cells was (1.81±0.99)% in THP-1 cells.A majority of the SP cells remained in the G0/G1 phase, and the expressions of CD34+ and CD34+ CD38- and the proliferative ability of the SP cells were higher than those of NSP cells (P<0.05). The mRNA expression of multidrug resistance genes (ABCG2, ABCB1), apoptosis regulation genes (Bcl-2) and the Bcl-2/Bax ratio of SP cells were higher than those of NSP cells.SP cells have been shown to be more tumorigenic than NSP cells.After co-culture with Ara-C, the proportion of SP cells increased significantly and presented in a concentration-dependent manor. Conclusions All of these findings suggest that the THP-1 cell line contains SP cells and the SP cells possess some intrinsic stem cell properties.The proportion of SP cells can be increased when co-cultured with Ara C, and this technique is a useful and important application for the study of LSCs. Key words: THP-1 cell line; Leukemia stem cells; Side population cells; Ara-C