In vitro and in vivo targeting imaging of pancreatic cancer using a Fe₃O₄@SiO₂ nanoprobe modified with anti-mesothelin antibody

Abstract

Pancreatic cancer is a highly malignant disease with a 5-year survival rate <5% mainly due to lack of early diagnosis and effective therapy. In an effort to improve the early diagnostic rate of pancreatic cancer, a nanoprobe Fe₃O₄@SiO₂ modified with anti-mesothelin antibody (A-MFS) was prepared to target cells and tumor tissues highly expressing mesothelin in vitro (human pancreatic cancer cell line SW1990) and in vivo (subcutaneously transplanted tumors) studies. The A-MFS probe was successfully prepared and was spherical and uniform with a hydrodynamic diameter between 110 and 130 nm. Cell Counting Kit-8 testing indicated that A-MFS was nontoxic in vitro and in vivo studies. The in vitro study showed that the A-MFS probe specifically targeted SW1990 cells with high mesothelin expression. The in vivo study was conducted in Siemens 3.0 T magnetic resonance imaging. The average T2-weighted signal values of the xenografts were 966.533±31.56 before injecting A-MFS and 691.133±56.84 before injecting saline solution. After injection of 0.1 mL A-MFS via nude mouse caudal vein for 2.5 hours, the average T2-weighted signal of the xenograft decreased by 342.533±42.6. The signal value decreased by −61.233±33.9 and −58.7±19.4 after injection of the saline and Fe₃O₄@SiO₂. The decrease of tumor signal by A-MFS was much more significant than that by saline and Fe₃O₄@SiO₂ (P<0.05). The results demonstrated the high stability and nontoxicity of A-MFS, which effectively targeted pancreatic cancer in vitro and in vivo. A-MFS is a promising agent for diagnosis of pancreatic cancer.

Keywords:

• nanoprobe
• mesothelin
• Fe₃O₄@SiO₂
• pancreatic cancer
• targeted imaging

Supplementary materials

Stability of dispersion test

In order to observe the stability of A-MFS in solution, different concentrations of A-MFS solutions (50 mg/mL, 100 μg/mL, 150 μg/mL, 200 μg/mL) were rested at room temperature for different times (0, 4, 24 hours). The optical images were taken to reflect their stability. Results show that the nanoparticle has a good dispersion at macro level, as shown in Figure S1.

In vivo MRI test of FS

Three mice were injected with 1 mg/mL of Fe₃O₄@SiO₂ (FS) (0.1 mL per mouse), respectively, via caudal veins. All the images of mice were obtained using Siemens 3.0 T magnetic resonance scanner. The T2 signal values of xenograft were decreased by −58.7±19.4 after injection of the FS at 2.5 hours. Results showed that the decrease of tumor signal by A-MFS was much more significant than that by FS (P>0.05). Images are shown in Figures S1 and S2. It should be noted that the decrease of tumor signal by FS at 5 hours (53.7±15.1) was also more significant than that by saline (P>0.05). It may be the result of passive targeting of material. But, the decrease of signal by FS at 5 hours is still less than that by A-MFS.

Figure S1 Stability of A-MFS solution with different concentrations.

Abbreviation: A-MFS, anti-mesothelin antibody.

Figure S2 MRI T2 images of FS group.

Note: The signal of xenograft did not decrease significantly after injection of FS.

Abbreviations: MRI, magnetic resonance imaging; FS, Fe₃O₄@SiO₂.

Figure S3 The T2-weighted quantitative signals of tumor before and after injection of FS.

Note: The signal of xenograft did not decrease significantly after injection of FS.

Abbreviations: FS, Fe₃O₄@SiO₂; SE, standard error; min, minutes; h, hours.

Acknowledgments

This work was supported by the Natural Science Foundation of China (No 51302190 and No 30970801), Shanghai Talent Development Fund (2012043), and Specialized Research Fund for the Doctoral Program of Higher Education, SRFDP (20130072120029).

Disclosure

The authors report no conflicts of interest in this work.