KA2012MBL Induces Apoptosis And Cell Cycle Arrest In Human Leukemia K562/S Cells

Objective: KA2012 MBL is a liquid extract from oyster meat. It is a mixture rich in amino acids, plant polysaccharides, taurine, vitamins, trace elements and other bioactive substances. The aim of this project is to investigate the cytotoxicity of KA2012 MBL on malignant K562 cells and HGC-27 cells and underlying mechanisms.Methods: 1. Cytotoxic activity of KA2012 MBL Human leukemia cell K562, human gastric cancer cells HGC-27 were employed to test the cytotoxic activity of KA2012 MBL at different concentrations after 48 h incubation using SRB assay. Microplate reader was employed to measure the absorbance. Cell survival rate was calculated(survival rate(%)) =(TB) /(UB) × 100%) 2. The effect of KA2012 MBL on P-gp-mediated multidrug resistance Inhibitory effects of KA2012 MBL and P-gp substrate doxorubicin at different concentrations on K562 P-gp high expression line(K562/A) and P-gp low expression line(K562/S) was detected by SRB assay. 3. Underlying mechanism of anti-tumor effect of KA2012MBL(1) The effect of KA2012 MBL on apoptosis, cell cycle arrest and mitochondrial membrane potential of K562/S cells. After incubation of K562/S with KA2012 MBL for 48 h, flow cytometry was performed to detect the effect of KA2012 MBL on apoptosis, cell cycle arrest and mitochondrial membrane potential of K562 / S cell.(2) The effect of KA2012 MBL on apoptosis-related proteins of K562/S cells. After incubation of K562/S with KA2012 MBL for 48 h, cell proteins were extracted. Western blot was performed to detect the expression of apoptosis-related proteins Bcl-2 and Bax.Results: 1. Proliferation of human leukemia cell line K562 and human gastric cancer cells HGC-27 was inhibited dose dependently by KA2012 MBL after 48 h incubation. 2. KA2012 MBL has similar cytotoxic effect on K562/A and K562/S cells with IC50 values 1.10±0.17 and 1.11±0.16(v/v%) compared with IC50 values 54.58±2.48 and 8.08±0.75( μM) of doxorubicin, indicating that KA2012 MBL can overcome P-gp-mediated multidrug resistance of K562/A cells. 3. KA2012 MBL can effectively induce apoptosis, increase mitochondrial membrane potential, and decrease mitochondrial membrane permeability of K562/S cells at concentration >1.6%(v/v%). It also increased the expression of anti-apoptotic protein Bcl-2 and decreased the expression of pro-apoptotic protein Bax and decreased intracellular ATP level in K562/S cells. Furthermore, KA2012 MBL arrested cell cycle of K562/S cells in the S phase.Conclusion: 1. KA2012 MBL inhibit the proliferation of human leukemia cell line K562/S and human gastric cancer cell line HGC-27. 2. KA2012 MBL can effectively overcome P-gp-mediated multidrug resistance in P-gp high expressing K562/A human leukemia cells. 3. The underlying mechanisms of KA2012MBL’s antitumor activity include:(1) decrease Bcl-2/Bax ratio;(2) decrease mitochondrial membrane continuity and reduce membrane potential, thereby opening the mitochondrial apoptotic pathway to kill tumor cells;(3) arrest the cell cycle of tumor cells at S phase.