5-FU-Injured Bone Marrow Stromal Cells Initiate Stress-induced Premature Senescence of Hematopoietic Cells

Abstract

To investigate the damage effect of 5-fluorouracil(5-FU) with tumor inhibition concentration on human bone marrow mesenchymal stem cells (hBMSC) and influence of its effect on the hematopoietic cells. The Cell Counting Kit-8 was used for determining the sensitivity of breast cancer cell line MCF-7, colon cancer cell line HCT-116 and HS-5 derived from human bone marrow stronal cell line to the different doses of 5-fluorouracil in vitro. After HS-5 was treated with 5-fluorouracil, crystal violet staining assay was used to count the number of colony forming unit-fibroblast, the distribution of cell cycle was analyzed by flow cytometry (FCM), apoptosis was assessed by Annexin V/PI double-stained method and Hoechest staining; DCFH-DA staining was used to analyse the level of reactive oxygen species (ROS), ELISA and immuofluorescence were used to detect cytokines KL, GM-CSF, RANTS and SDF. The hUCB-MNC was counted by trypan blue staining after co-culture with HS-5, FCM was used to detect the cell cycle distribution, ROS level and the ratio of CD34+ cells. The levels of glutathione peroxidase (GSH-Px) and total superoxide dismutase(T-SOD) were measured by enzymatic assay. The senescence associated-β-galactosidase (SA-β-Gal) staining was used to detect the senescent hUCB-MNC. 5-Fluorouracil of 12.5 µg/ml-100 µg/ml inhibited the proliferation of MCF-7, HCT-116 and HS-5 cells in dose-dependent and time-dependent manner, among them HS-5 was more sensitive to 5- fluorouracil. After treatment with 5-fluorouracil, the HS-5 cell cycle was blocked. The apoptosis rate and the intracellular ROS level of HS-5 significantly increased. Also HS-5-secreted hematopoietic growth factors decreased and inflammatory chemokines increased. After co-cultured with 5-fluorouracil-treated HS-5, the number of hUCB-MNC and the ratio of CD34+ cells were decreased. hUCB-MNC cell cycle blocked in G1 phase. The antioxidant capacity also decreased and the intracellular ROS level increased significantly. The senescent hUCB-MNC increased. 5-Fluorouracil can result in oxidative damage of bone marrow stromal cells and change of function secreting bioactivators, thus induce oxidative stress in hematopoietic cells to initiate stress-induced premature senescence (SIPS).