ABSTRACT
This study was aimed to examine the correlation of the cytotoxic effects induced by two types of TNF-α to cell cycle. Hoechst 33342 and PI were used to detect the morphological changes in the cell death induced by the two types of TNF-α. TdT and PI co-staining was performed to determine the phase of cell cycle of apoptotic cells. L929 cells in different phases of cell cycle were further synchronized and their sensitivity to the two types of TNF-α was observed. Our results showed that the apoptosis of HepG2 cells triggered by tm-TNF-α mainly occurred in G(1) phase while in HL-60, Raji and K562 cell lines it mainly took place in S phase. The apoptosis of L929 cells induced by tm-TNF-α mainly occurred in S phase while the apoptosis induced by s-TNF-α mainly appeared in G(1) phase. L929 cells were sensitive to s-TNF-α when synchronized in G(1) phase (cytotoxicity 49.8%) while their sensitivity to tm-TNF-α was highest in S phase (45.7%) and G(1)/S phase (cytotoxicity 40.6%). It was concluded that tm-TNF-α-induced apoptosis of different target cells took place in different phases of cell cycle. The apoptosis of the specific cell line induced by the two types of TNF-α occurred in different phases of cell cycle. The sensitivity of the specific cell line to the two types of TNF-α was correlated with the phase of cell cycle.
ABSTRACT
This study was aimed to examine the correlation of the cytotoxic effects induced by two types of TNF-α to cell cycle. Hoechst 33342 and PI were used to detect the morphological changes in the cell death induced by the two types of TNF-α. TdT and PI co-staining was performed to determine the phase of cell cycle of apoptotic cells. L929 cells in different phases of cell cycle were further synchronized and their sensitivity to the two types of TNF-α was observed. Our results showed that the apoptosis of HepG2 cells triggered by tm-TNF-α mainly occurred in G(1) phase while in HL-60, Raji and K562 cell lines it mainly took place in S phase. The apoptosis of L929 cells induced by tm-TNF-α mainly occurred in S phase while the apoptosis induced by s-TNF-α mainly appeared in G(1) phase. L929 cells were sensitive to s-TNF-α when synchronized in G(1) phase (cytotoxicity 49.8%) while their sensitivity to tm-TNF-α was highest in S phase (45.7%) and G(1)/S phase (cytotoxicity 40.6%). It was concluded that tm-TNF-α-induced apoptosis of different target cells took place in different phases of cell cycle. The apoptosis of the specific cell line induced by the two types of TNF-α occurred in different phases of cell cycle. The sensitivity of the specific cell line to the two types of TNF-α was correlated with the phase of cell cycle.
Subject(s)
Humans , Apoptosis , Cell Cycle , Cell Line, Tumor , HL-60 Cells , Hep G2 Cells , K562 Cells , Membrane Proteins , Metabolism , Pharmacology , Tumor Necrosis Factor-alpha , Metabolism , PharmacologyABSTRACT
Our previous study showed that transmembrane TNF-alpha (TM-TNF-alpha) had broader tumoricidal spectrum than secretory TNF-alpha (s-TNF-alpha). This study examined the difference between the two kinds of TNF-alpha in inducing cells and the relationship between the apoptosis induced by TM-TNF-alpha and the cell cycle. Bioassay was employed to compare the cytotoxic effect of two kinds of TNF-alpha on cell lines L-929 and HepG2. TUNEL was used to detect apoptosis and the TdT and PI co-staining were used for determining the phase of apoptotic cells. Our results showed that TM-TNF-alpha could kill not only s-TNF-sensitive L929 cells but also s-TNF-tolerant HepG2 cells. TM-TNF-alpha predominantly induced apoptosis while s-TNF could induce both apoptosis and necrosis. The apoptosis of L-929 cells induced by TM-TNF-alpha mainly occurred in S phase and the apoptosis of HepG2 predominantly took place in G(1) phase. It is concluded that the cytotoxic effects of the two TNF differ substantially. Since TM-TNF-alpha works locally, mainly induces apoptosis and has broader anti-tumor spectrum, it may be more effective for the treatment of tumor than s-TNF.
ABSTRACT
Our previous study showed that transmembrane TNF-α (TM-TNF-α) had broader tumoricidal spectrum than secretory TNF-α (s-TNF-α). This study examined the difference between the two kinds of TNF-α in inducing cells and the relationship between the apoptosis induced by TM-TNF-α and the cell cycle. Bioassay was employed to compare the cytotoxic effect of two kinds of TNF-α on cell lines L-929 and HepG2. TUNEL was used to detect apoptosis and the TdT and PI co-stainin gwere used for determining the phase of apoptotic cells. Our results showed that TM-TNF-α could kill not only s-TNF-sensitive L929 cells but also s-TNF-tolerant HepG2 cells. TM-TNF-α predominantly induced apoptosis while s-TNF could induce both apoptosis and necrosis. The apoptosis of L-929 cells induced by TM-TNF-α mainly occurred in S phase and the apoptosis of HepG2 predominantly took place in G1 phase. It is concluded that the cytotoxic effects of the two TNF differ substantially.Since TM-TNF-α works locally, mainly induces apoptosis and has broader anti-tumor spectrum, it may be more effective for the treatment of tumor than s-TNF.