Early Monitoring Of Response To Chemotherapy By^99mTc-MIBI、¹⁸F-FDG And¹⁸F-FLT Uptake In Drug-resistant Breast Cancer Cells

Part One: A study on the early changes of^99mTc-MIBI uptake indrug-resistant breast cancer cells after chemotherapy in vitroObjective To establish a reliable method to detect the^99mTc-MIBI uptake in breastcancer cell lines MCF-7and MCF-7/Taxol in vitro. To examine whether^99mTc-MIBI canbe used for chemosensitivity testing by investigating the uptake change of^99mTc-MIBIafter chemotherapy in human breast cancer cell lines MCF-7and MCF-7/Taxol.Methods The uptake of^99mTc-MIBI in human breast cancer cell lines MCF-7wasdetected at different experimental conditions （cell number1.25×105².5x106, incubationtime20¹20min, radioactivity1.85²9.6KBq, and glucose concentration0¹1.1mmol/L）,and the suitable experimental conditions were chosen. The uptake of^99mTc-MIBI wasmeasured after the cells were exposed to different does of5-FU （0,0.125,0.25,0.5,1.0mg/mL） at different times （24h,48h,72h）. Then the uptake inhibition rate of each group（△MIBI）was calculated. The cell growth inhibition rate was calculated by MTT colorimetricassay. ANOVA and correlation analysis were applied to observe the correlation between theupatke inhibition rate of^99mTc-MIBI and cell proliferation.Results The uptake rate of^99mTc-MIBI in MCF-7cells was positively correlated withthe cell number, incubation time and glucose concentration within a certain range, but wasunrelated to radioactivity. The uptake rate of^99mTc-MIBI in MCF-7cells was （21.58±1.37）%when the cell number was1×106/hole, the incubation time was100min, theglucose concentration was0mmol/L and the radioactivity was3.7KBq. It is obviouslyhigher than that in MCF-7/Taxol cells. The cell proliferation was significantly inhibitedafter chemotherapy. The uptakes of^99mTc-MIBI was negatively correlated with the dosesof5-FU.（1） The^99mTc-MIBI uptake inhibition rate（△MIBI） in MCF-7cells at24hours after different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL） wa（s25.08±6.23）%（,32.02±5.84）%,（34.63±7.42）%,（34.70±2.64）%and48hours was（68.57±4.67）%,（77.06±8.95）%（,82.21±4.70）%（,83.27±4.10）%and72hours was（77.32±1.79）%,（91.62±1.33）%,（93.01±1.62）%,（93.58±1.00）%, respectively.△MIBIwas positivelycorrelated with the cell growth inhibition rate at48hours（r=0.484, P＜0.05）and72hours（r=0.672, P＜0.01）, respectively.（2） The^99mTc-MIBI uptake inhibition rate（△MIBI） inMCF-7/Taxol cells at24hours after different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL）was （23.43±2.93）%,（30.21±8.46）%,（30.23±8.58）%,（35.11±8.44）%and48hours was （38.11±4.93）%,（41.65±6.98）%,（42.37±1.02）%,（49.85±9.73）%and72hours was（46.18±1.93）%,（48.20±7.43）%,（49.21±1.79）%,（62.73±5.16）%.△MIBIwas positively correlated with the cell growth inhibition rate at48hours （r=0.438, P＜0.05）.Conclusion The uptake of^99mTc-MIBI in MCF-7cells was higher than that inMCF-7/Taxol cells. The response of chemotherapy in human breast cancer cells could bepredicted by^99mTc-MIBI uptake as early as48h in vitro.Part Two: A study on the early changes of¹⁸F-FDGuptake indrug-resistant breast cancer cells after chemotherapy in vitroObjective To establish a reliable method to detect the¹⁸F-FDGuptake in breastcancer cell lines MCF-7and MCF-7/Taxol in vitro. To examine whether¹⁸F-FDGcan beused for chemosensitivity testing by investigating the uptake change of¹⁸F-FDGafterchemotherapy in human breast cancer cell lines MCF-7and MCF-7/Taxol.Methods The uptake of¹⁸F-FDGin human breast cancer cell lines MCF-7wasdetected at different experimental conditions （cell number1.25×105².5x106, incubationtime20¹20min, radioactivity1.85²9.6KBq, and glucose concentration0¹1.1mmol/L）,and the suitable experimental conditions were chosen. The uptake of¹⁸F-FDGwasmeasured after the cells were exposed to different does of5-FU （0,0.125,0.25,0.5,1.0mg/mL） at different times （24h,48h,72h）. Then the cell uptake inhibition rate and ofeach group（△FDG）was calculated. The cell growth inhibition rate was calculated by MTTcolorimetric assay and the cell viability was measured by fiow cytometry. ANOVA andcorrelation analysis were applied to observe the correlation between the upatke inhibition rate of^99mTc-MIBI and cell proliferation.Results The uptake rate of¹⁸F-FDGin MCF-7cells was positively correlated with thecell number, incubation time and glucose concentration within a certain range, but wasunrelated to radioactivity. The uptake rate of¹⁸F-FDGin MCF-7cells was （41.26±0.86）%when the cell number was1×106/hole, the incubation time was100min, the glucoseconcentration was0mmol/L and the radioactivity was3.7KBq. It is obviously higher thanthat in MCF-7/Taxol cells.The cell proliferation was significantly inhibited afterchemotherapy. And the early apoptosis was also affected after chemotherapy. The uptakesof¹⁸F-FDGwas negatively correlated with the doses of5-FU.（1） The¹⁸F-FDGuptakeinhibition rate（△FDG） in MCF-7cells at24hours after different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL） was（40.03±6.19）%,（48.05±7.57）%,（51.88±3.10）%,（55.69±2.69）%and48hours was（76.21±4.05）%,（82.13±6.42）%,（87.33±2.47）%,（89.03±2.99）%and72hours was（47.99±2.70）%、(49.20±0.78%、（51.44±1.13）%、（62.13±4.52）%, respectively.△FDGwas positively correlated with the cell growthinhibition rate at24hours（r=0.600, P＜0.01）,48hour（sr=0.841, P＜0.01）and72hours（r=0.708, P＜0.01）.（2） The¹⁸F-FDGuptake inhibition rate（△FDG） in MCF-7/Taxol cellsat24hours after different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL） was（22.53±9.74）%,（40.75±3.44）%,（49.40±6.23）%,（64.58±5.52）%and48hours was （52.05±4.02）%,（78.81±2.50）%,（86.54±0.44）%,（87.26±1.23）%and72hours was（16.23±3.50）%,（27.74±6.79）%,（47.83±3.76）%,（53.78±6.52）%.△FDGwaspositively correlated with the cell growth inhibition rate at24hours（r=0.401, P=0.052）,48hours（r=0.726, P＜0.01）and72hours（r=0.586, P＜0.01）.Conclusion The correlation between the uptake inhibition rate of¹⁸F-FDGand cellproliferation was different after the cells were exposed to different does of5-FU atdifferent times, and the correlation at48hours was perfect. And the¹⁸F-FDGuptake wascorrelated with the early apoptosis.The response of chemotherapy in human breast cancercells could be perfectly evaluated by¹⁸F-FDGuptake as early as24h in vitro. Part Three: A study on the early changes of¹⁸F-FLT uptake in breastcancer cells after chemotherapy in vitroObjective To establish a reliable method to detect the¹⁸F-FLT uptake in breast cancercell lines MCF-7in vitro. To examine whether¹⁸F-FLT can be used for chemosensitivitytesting by investigating the uptake change of¹⁸F-FLT after chemotherapy in human breastcancer cell lines MCF-7.Methods The uptake of¹⁸F-FLT in human breast cancer cell lines MCF-7wasdetected at different experimental conditions （incubation time20¹20min, radioactivity1.85²9.6KBq, and glucose concentration0¹1.1mmol/L）, and the suitable experimentalconditions were chosen. The uptake of¹⁸F-FLT was measured after the cells were exposedto different does of5-FU （0,0.125,0.25,0.5,1.0mg/mL） at24hours. Then the cell uptakeinhibition rate （△FLT） was calculated.Results The uptake rate of¹⁸F-FLT in MCF-7cells was positively correlated with theincubation time and glucose concentration within a certain range, but was unrelated toradioactivity. The uptakes of¹⁸F-FLT was negatively correlated with the doses of5-FU.（1）The¹⁸F-FLT uptake rate in MCF-7cells at24hours after different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL） was（20.35±1.38）%,（16.52±0.85）%,（12.68±0.21）%,（9.84±0.36）%,（8.87±1.14）%.（2） The¹⁸F-FLT uptake inhibition rate（△FLT） in MCF-7cellsat24hours after different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL） was（18.84±4.19）%,（37.69±1.03）%,（51.63±1.76）%,（56.43±5.63）%.Conclusion The uptake rate of¹⁸F-FLT in MCF-7cells was positively correlated withthe incubation time and glucose concentration within a certain range, but was unrelated toradioactivity. The response of chemotherapy in human breast cancer cells could bepredicted by¹⁸F-FLT uptake as early as24h in vitro.Part Four: A comparative studyon early monitoring of response tochemotherapy by^99mTc-MIBI and¹⁸F-FDGuptake in drug-resistantbreast cancer cells in vitroObjective To compare the ability of evaluating the response to chemotherapy by^99mTc-MIBI uptake with by¹⁸F-FDGuptake.Methods The suitable experimental conditions were chosen. The uptake of^99mTc-MIBI and¹⁸F-FDGwas measured after cells were exposed to different does of5-FU（0,0.125,0.25,0.5,1.0mg/mL） at different times （24h,48h,72h）. Then the uptake inhibition rate of each group was calculated. The cell growth inhibition rate was calculatedby MTT colorimetric assay. ANOVA and correlation analysis were applied to observe thecorrelation between uptake inhibition rate of^99mTc-MIBI and cell proliferation in MCF-7（or MCF-7/Taxol）.Results The uptake and proliferation were significantly inhibited by chemotherapy.（1）△MIBIin MCF-7cells was positively correlated with the cell growth inhibition rate at48hours（r=0.484, P＜0.05）and72hours（r=0.672, P＜0.01）;△MIBIin MCF-7/Taxol cellswas positively correlated with the cell growth inhibition rate at48hours（r=0.438, P＜0.05）.（2）△FDGin MCF-7cells was positively correlated with the cell growth inhibitionrate at24hour（sr=0.600, P＜0.01）,48hour（sr=0.841, P＜0.01）, and72hour（sr=0.708,P＜0.01）;△FDGin MCF-7/Taxol cells was positively correlated with the cell growthinhibition rate at48hours（r=0.726, P＜0.01）and72hours（r=0.586, P＜0.01）.Conclusion The uptake inhibition rate of¹⁸F-FDGin MCF-7cells and MCF-7/Taxolwas almost all higher than that of^99mTc-MIBI after chemotherapy at24hours and48hours.The most appropriate time in which^99mTc-MIBI and¹⁸F-FDGuptake could evaluate theresponse to chemotherapy was different.