LTD4 Mediates Proliferation And Apoptosis In Chronic Myelogenous Leukemia Cells K562 In Vitro

Objective : Bone marrow microenvironment(BMM) not only support hematopoietic cells growth and differentiation,but also contribute to tumor cells growth.BMM play a critical role in proliferation,differentiation and apoptosis of tumor cells. LTD4 exists in BMM in the present study, we investigated the effects of LTD4 on proliferation and apoptosis of chronic myelogenous leukemia cell line K562 cells, in order to provide theoretical support for a new strategy on reversing drug-resistance and the therapy of leukemia by means of modifying the leukemic hemopoietic microenvironment.Methods: 1.Bone marrow stromal cells were grown from bone marrow mononuclear cells obtained from 6 cases of normal and 6 cases of leukemia individuals, the content of LTD4 in supernatant from marrow stromal cell cultivation was investigated by enzyme-linked immunoadsordent assay (ELISA). 2. Human leukemia cells line K562 cells were cultured.and directly stimulated with different concentrations of LTD4 for 48h in vitro. CCK-8 assay was used to examine the effect of inducing growth. Annexin V/PI staining was used to detect the effect of apoptosis. The expressions of related gene mRNA was detected by RT-PCR.Results: 1. The mean content of LTD4 in supernatant from leukemic stromal cell culture was 1684.5±185.1 pg/ml, significantly higher than that from normal stromal culture(1192.5±89.6 pg/ml)(P<0.05). 2. The results of CCK-8 and AnnexinV-FITC/PI double staining FCM assay showed LTD4 could induce the proliferation and restrain apoptosis of K562 cell. Along with the increase of LTD4 concentrations, these effects were enhanced. The results of RT-PCR showed LTD4 could increase the expression of CysLTR gene at mRNA level.The expression of CysLTR gene mRNA was increased more obviously with the increase of concentrations,.Conclusions: 1.The content of LTD4 in supernatant from leukemic stromal cell culture was significantly higher than that from normal stroma culture, which suggested that high excretion of LTD4 contributed to disfunction of leukemic microenvironment. 2. There was high expression of CysLTR in human K562 cells, and LTD4 could induce significant proliferations and apoptosis of K562 cells.