| Purpose:To investigate the synergistic anticancer effects of static magnetic fields with adriamycin(ADM),cisplatin(DDP) on K562 cells or SW480 cells,and the different cytological mechanism of the synergistic anticancer effects.Methods:1.The survival of suspension cancer cells(K562 cells) exposed to SMF or/and adriamycin were detected by MTT test.The survival of adherent cancer cells (SW480) exposed to SMF and cisplatin were detected by MTT test.2.The cell cycle distribution and DNA damage of K562 cells or SW480 cells induced by SMF or/and ADM,DDP were investigated by flow cytometer(FCM) and single cell gel electrophoresis(SCGE),respectively.3.After exposured to SMF or/and ADM,DDP,The cell membrane structure and internal structure were observed by optical microscope,atomic force microscope(AFM) and transmission electron microscope (TEM).The expressions of P-glycoprotein(P-gp) were analyzed by immunofluorescence of FCM.Resuits:1.(1) The anticancer effect of ADM or DDP on K562 cells/SW480 cells was concentration- and time-dependent.(2) The growth of K562 cells were inhibited after cells were incubated with 35ng/mL ADM for 12hr(p＜0.05).(3) The growth of SW480 cells were inhibited after cells were incubated with 2μg/mL DDP for 12hr (p＜0.05).2.(1) Combination of 9mT SMF and 25 ng/mL ADM for 12h could inhibit the cell activity of K562 cells significantly(P＜0.05),while neither ADM nor SMF could influence cell activity;(2) The activity of SW480 cells can not be inhibited after cells were treated with 1μg/mL DDP or 9mT SMF alone for 12 hr.But the cell activity of combined treatment group(1μg/mL DDP+SMF) in SW480 was significantly reduce, compared with controls or DDP group(p＜0.05 or p＜0.01).3.(1)When K562 cells were treated with only 9mT SMF for 12hr,the proportion of cells in G2/M phase were increased compared to controls;when K562 cells were treated with only 25ng/mL ADM for 12hr,the proportion of cells in S and G2/M phase increased compared to control,respectively.K562 cells were treated with the combination of ADM and SMF for 12hr,cells were almost blocked in G2/M phase;(2) DNA damage could not be detected by SCGE when K562 cells only exposed to 9mT SMF for 12 hr;DNA damage of K562 cells treated with 25ng/mL ADM for 12hr was significantly different controls(p＜0.05);If treated with the combination of ADM and SMF for 12hr,DNA damage was increased significantly compare with other three groups(p＜0.01),respectively;The survival of SW480 cells can not be inhibited after treatment with 1μg/mL DDP for 12hr or exposure to 9mT SMF for 12 hr.(3)However, there were no DNA damage when primary human lymphocyte were treated with ADM or/and SMF.4.(1)If SW480 cells were treated with only 9mT SMF for 12hr,the number of cells in G2/M phase increased compared to control;If treated with only 1μg/mL DDP for 12hr,the distribution of cell cycle was relatively average;If treated with the combination of DDP and SMF for 12hr,the most of cells were blocked in G1 phase;.(2) For SW480 cells,1μg/mL DDP or/and 9 mT SMF have no detectable effect on Tail Length,Tail DNA%,and Head DNA%.But,after treated with DDP or combination of DDP and SMF,the area of head was significantly reduced(p＜0.01).5.(1)Light microscope was used to observe the cell morphological modification. The cells exposed to SMF had no detectable changes.The edge of the cells treated with ADM became rough.Exposure to SMF and ADM lead to cell death,many big vacuoles appeared in the cytoplasm and plasma membrane broke down,and the cell debris also could be observed.(2) The modification of cell surface was observed by AFM.For K562 cells,the surface of cells exposed to SMF became rough,hollows appeared on the cell surface.The damage of the cell surface treated with ADM aggravated.The surface structure of cells treated with SMF plus ADM was injured severely,deeper hollows were detected under AFM.(3) The same results could be observed under SEM.After treatment with 25ng/mL ADM for 12hr,many small vacuoles appeared in K562 cells cytoplasm,and hole-like structures on membrane;After exposure to 9mT SMF for 12 hr, hollows appeared on membrane;After treatment with ADM and SMF,the number and volume of vacuoles increased,the damage of membrane became more serious.(4) Immunofluorescence results demonstrate that treated with 25ng/mL ADM for 12hr can improve the expression of P-gp,but exposure to 9mT SMF for 12 hr can repress the expression of P-gp.Meanwhile treatment with ADM and SMF also repress the expression of P-gp.(5) For SW480 cells,the surface of cells exposed to magnetic field became rough,hollows appeared on the cell surface.The damage of the cell surface treated with DDP were aggravated.The surface structure of cells treated with SMF plus DDP was injured severely,anomalous hollows were detected under AFM.(6)For SW480 cells,after exposure to 9mT SMF for 12 hr,F-actin became more confused; After treatment with 1μg/mL DDP for 12 hr,F-actin congregate along cell membrane which form many protuberance;After treatment with DDP and SMF,the protuberance on the surface of membrane disappeared,but F-actin disassociated in some extend and more confused.Conclusion:(1) Magnetic fields and ADM have synergistic anticancer effect on K562 cells under certain condition.Magnetic fields and DDP have synergistic anticancer effect on SW480 cells under certain condition.(2) For K562 cells,the cytological mechanism of the synergistic anticancer effects maybe induced by the damage of structure of cell membrane,changes of cell internal ultrastructure,cell cycle arrest in G2/M phase and DNA damage.Meanwhile,SMF exposure can reduce the expression of P-gp,but treatment with ADM can improve the expression of P-gp.(3)For SW480 cells,the cytological mechanism of the synergistic anticancer effects maybe induced by the damage of structure of cell membrane,changes of cell internal structure,especially for cytoskeleton,cell cycle arrest in G1 phase. Different from K562 cells,the synergistic mechanism also was induced by adhesion function.After treatment with DDP and SMF,F-actin disassociated and confused,As a result,cells lost the ability to adhere to substrate and lack growth stimulative signal, resulting in cell cycle arrestment in G1. |
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