OBJECTIVETo investigate the toxicological mechanism of microcystin-LR (MCLR) on L-02 cells.

METHODSL-02 cells was treated with MCLR at different concentrations and the subsequent changes such as cell proliferation (MTT assay), morphology, lactate dehydrogenase (LDH) leakage, apoptosis rate and apoptosis-related gene expression were examined.

RESULTSMTT assay showed that MCLR mildly inhibited the cell growth within the initial 24 h of treatment but enhanced the cell viability after that till 60 h in a time- and dose-dependent manner. LDH leakage underwent no marked changes in response to 48-hour MCLR treatment but increased upon prolonged treatment for 60 h, indicating the presence of oxidative damage. After a 48-h treatment with MCLR at 50 microg/ml, obvious apoptosis of L-02 cells occurred as manifested by cell rounding, detachment from the substrate, cell shrinkage and membrane blebbing. The apoptosis rates were rather low (between 22% and 29%) after treatment with MCLR at different concentrations for 36 h, and increased to as much as 80% after a 60-h treatment with 50 microg/ml MCLR. The expressions of p53 and bcl-2 increased in the cells after treatment with high-concentration MCLR, suggesting that MCLR up-regulated the expression levels of the two proteins.

CONCLUSIONMCLR can induce apoptosis and up-regulate p53 and bcl-2 expressions in human normal liver cell line L-02.

Apoptosis ; drug effects ; Cell Line ; Hepatocytes ; cytology ; Humans ; Microcystins ; toxicity ; Proto-Oncogene Proteins c-bcl-2 ; biosynthesis ; genetics ; Tumor Suppressor Protein p53 ; biosynthesis ; genetics

BACKGROUNDMacrophage stimulating protein (MSP) is produced by human bone marrow endothelial cells. In this study, we sought to observe its effects on inducing the expansion of early hematopoietic progenitor cells which were cultured in a liquid culture system in the presence of the combination of stem cell factor (SCF), interleukin 3 (IL-3), interleukin 6 (IL-6), granulocyte macrophage-colony stimulating factor (GM-CSF), erythropoietin (EPO) (Cys) and MSP or of Cys and bone marrow endothelial cell conditioned medium (EC-CM).

METHODSHuman bone marrow CD34(+) cells were separated and cultured in a liquid culture system for 6 days. Granulocyte-macrophage colony forming unit (CFU-GM) and colony forming unit-granulocyte, erythrocyte, macrophage, megakaryocyte (CFU-GEMM) were employed to assay the effects of different treatment on the proliferation of hematopoeitic stem/progenitor cells. The nitroblue tetrazolium (NBT) reductive test and hoechest 33258 staining were employed to reflect the differentiation and apoptosis of the cells respectively.

RESULTSMSP inhibited the proliferation of CFU-GM and CFU-GEMM in semi-solid culture and the inhibitory effect on CFU-GEMM was stronger than on CFU-GM. MSP inhibited the differentiation of early hematopoietic progenitor cells induced by hematopoietic stimulators. Bone marrow (BM) CFU-GEMM was 2.3-fold or 1.7-fold increase or significantly decreased in either Cys + EC-CM, Cys + MSP or Cys compared with 0 hour control in liquid culture system after 6 days.

CONCLUSIONMSP, a hematopoietic inhibitor, inhibits the differentiation of early hematopoietic progenitor cells induced by hematopoietic stimulators and makes the early hematopoietic progenitor cells expand in a liquid culture system.

Antigens, CD34 ; analysis ; Apoptosis ; drug effects ; Cell Differentiation ; drug effects ; Cells, Cultured ; Chemokine CCL3 ; Chemokines, CC ; pharmacology ; Hematopoietic Stem Cells ; drug effects ; Hepatocyte Growth Factor ; pharmacology ; Humans ; Proto-Oncogene Proteins ; pharmacology