AIM:To investigate the feasibility for antisense imaging ofthe colon cancer with liposome-entrapped 99 m-technetiumlabeled antisense oligonucleotides as tracers.METHODS:Fifteen mer single-stranded aminolinkedphosphorothioate antisense oligonucleotides of c-mycmRNA were labeled with ~(99m)Tc-pertechnetate,then purifiedand finally entrapped with liposomes to form the labelingcompounds,liposome-entrapped ~(99m)Tc-labeled antisenseoligonudeotides.The LS-174-T cells(colon of adenocardnomacell line)were incubated with the labeling compounds totest the uptake rates of LS-174-T cells.Later on,a modelof 30 tumor bearing nude mice was constructed byinoculating with 5×10~6 of LS-174-T cells at right flank ofeach nude mouse.About 10 d later,the model wereadminstered by intravenous injection of the liposome-entrapped ~(99m)Tc-labeled antisense oligonucleotides.Thensome of the tumour bearing nude mice were sacrificed at0.5,1,2,and 4 h after intravenous injection,and properquantity of liver,spleen,tumor,etc.was obtained.Thetissues were counted in a gamma counter,and after correctionfor decay and background activity,expressed as a percentageof the injected dose.The others whose anterior andposterior whole-body scans were obtained at 1,1.5,2,4,6 and 24 h with a dual-head bodyscan camera equippedwith parallel-hole low-energy collimaters.The ratios ofradioactive counts in tumor to that in contralateral equivalentregion of abdomen were calculated.RESULTS:The uptake rates of LS-174-T cells for liposome-entrapped ~(99m)Tc-labeled antisense oligonucleotides increasedas time prolonged and reach the peak(17.77±2.41%)at 7 h.The biodistributions showed that the rdioactivity in thetumor(13.46±0.20%)of injected dose was the highest at2 h of intravenous injection of liposome-entrapped ~(99m)Tc-labeled antisense oligonucleotides,and then decreasedsharply to 4.58±0.45% at 4 h.The tumor was shown clearlyin the whole-body scan at 2 h of intravenous injection.Theratios,radioactive counts in tumor to that in contralateralequivalent region of abdomen(1.7332±0.2537),was thehighest one at 2 h after intravenous injection of liposome-entrapped ~(99m)Tc-labeled antisense oligonucleotides. The liposome-entrapped ~(99m)Tc-labeledantisense oligonucleotides deserve being developed intoradiopharmaceutics for the colon cancer imaging. AIM: To investigate the feasibility for antisense imaging of the colon cancer with liposome-entrapped 99m-technetiumlabeled antisense oligonucleotides as tracers. METHODS: Fifteen mer single-stranded aminolinkedphosphorothioate antisense oligonucleotides of c-mycmRNA were labeled with ~ (99m) Tc- pertechnetate, then purified and finally entrapped with liposomes to form the labelingcompounds, liposome-entrapped ~ (99m) Tc-labeled antisenseoligonudeotides. The LS-174-T cells (colon of adenocardium line) were incubated with the labeling compounds t -T cells. Fluid on, a model of 30 tumor bearing nude mice was constructed by inoculating with 5 × 10 ~ 6 of LS-174-T cells at right flank of a nude mouse. About 10 d later, the model were adminstered by intravenous injection of the Liposome-entrapped ~ (99m) Tc-labeled antisense oligonucleotides. Thensome of the tumor bearing nude mice were sacrificed at 0.5, 1, 2, and 4 h after intravenous injection, and properquantity of liver, spleen, t umor, etc.was obtained. the figures were counted in a gamma counter, and after correction for decay and background activity, expressed as a percentage of the injected dose. The others whose anterior and posterior whole-body scans were obtained at 1,1.5,2,4 , 6 and 24 h with a dual-head bodyscan camera with parallel-hole low-energy collimaters. The ratios of radioactive counts in tumor to that in contralateral equivalent area of ​​abdomen were calculated .RESULTS: The uptake rates of LS-174-T cells for The lipiodo-entrapped ~ (99m) Tc-labeled antisense oligonucleotides increased as time prolonged and reached the peak (17.77 ± 2.41%) at 7 h. The biodistributions showed that the rdioactivity in the tumor (13.46 ± 0.20%) of injected dose was the highest at2 h of intravenous injection of liposome-entrapped ~ (99m) Tc-labeled antisense oligonucleotides, and then decreased sharply to 4.58 ± 0.45% at 4 h. The tumor was shown clearly in the whole-body scan at 2 h of intravenous injection. Theratios, radioactive counts in tumor tothat in contralateralequivalent region of abdomen (1.7332 ± 0.2537), was thehighest one at 2 h after intravenous injection of liposome-entrapped ~ (99m) Tc-labeled antisense oligonucleotides. The liposome-entrapped ~ (99m) Tc-labeledantisense oligonucleotides deserve being developed intoradiopharmaceutics for the colon cancer imaging.