[Optimal time for MRI scanning of tumors in BALB/c mice using c-erbB2 antisense probe labeled with superparamagnetic iron oxide nanoparticles].

OBJECTIVE: To determine the optimal time for MRI scanning of tumors in BALB/c mice using c-erbB2 antisense probe labeled with superparamagnetic iron oxide nanoparticles. METHODS: SK-Br-3 tumor-bearing BALB/c mice (n= 30) were injected with antisense probe (12.0 mg Fe/kg). MRI scanning was performed on 5 mice before the injection and 60 min, 180 min, 360 min, 720 min and 1 440 min after the injection, respectively. Tumor tissues were taken immediately after the scanning and fixed with 10% formalin and paraffin-embedded sections. The MRI signal strength of the tumors and adjacent muscles were compared with changes detected under a microscope using HE and Prussian blue staining. RESULTS: SK-Br-3 tumors were introduced to the BALB/c mice successfully. The strongest signal intensity was detected by the MRI 360 min after injection with the antisense probe. The pathological examination revealed structural disorders of the tumor issues, with a large number of special-shaped cells arranged in a cancer nest shape. Punctuate blue iron particles were observed in all of the tumor issues, with the greatest density occurring at 360 min after the injection with the antisense probe. CONCLUSION: The MR4 optimal time for MRI scanning of tumors in BALB/c mice using c-erbB2 antisense probe labeled with superparamagnetic iron oxide nanoparticles should be set at 360 min after injection.

[Effects of magnetic c-erbB-2 antisense probe of different concentrations on morphology and expression of SK-Br-3 cancer cell lines in vitro].

OBJECTIVE: To explore the effects of the magnetic c-erbB-2 antisense probe of different concentrations on the morphology and expression of SK-Br-3 cancer cells in vitro. METHODS: Breast cancer SK-Br-3 cells were transfected for 24 h by antisense probe at an iron concentration of 5, 10, 25, 50, and 100 mg/L, respectively. The distribution and content of iron particles in SK-Br-3 cells was determined by Prussian blue staining, electron microscopy, and atomic absorption spectrometry. Cell viability was observed by trypan-blue exclusion and CCK-8 test. The protein expression of c-erbB-2 was assessed by the Western blot analysis. The changes of the signal strength were considered by magnetic resonance imaging (MRI). RESULTS: c-erbB-2 antisense probe was uptake by SK-Br-3 cells in a concentration-dependence manner within a certain range (5, 10, and the Medicine Scientific Research Project of Chongqing Health Bureau (062025)25 mg/L). When the probe concentration was 25 mg/L, iron content in cells was (18.38±0.28) pg, the cell vitality, survival, and c-erbB-2 protein expression were reduced significantly (all P<0.05), and the T2 value was lower significantly (P<0.05). However, the results of 50 mg/L or 100 mg/L group showed no significant difference with the 25 mg/L group (P>0.05). CONCLUSION: The magnetic c-erbB-2 antisense probe can effectively transfect and specifically inhibit the expression of SK-Br-3 cell lines at the iron concentration of 25 mg/L.