[Characteristics and in vitro imaging study of matrix metalloproteinase-2 targeting activable cell-penetrating peptide].
OBJECTIVE
To study invasively imaging MMP2-positive tumor cell by paramagnetic Gadolinium or fluorescein carried by a activable cell penetrating peptides.


METHODS
To label Fluorescein-5-isothiocyanate (FITC) and gadopentetate with the activable cell-penetrating peptides by a solid-phase synthesis method. Identification by TOF mass spectrum (TOF-MS). Isoelectric point of the activable cell penetrating peptides is determined by disc electrophoresis. T1 relacion of gadopentetate labeled with the activable cell-penetrating peptides (B) in water were determined on 400 MHZ NMR. Human lung cancer cell lines: A549 were respectively stained by FITC labeled with ACPPs (A) or FITC alone. MMP2 expression and activity were determined by zymography. T1WI signal of A549 incubated with 120 nmol/ml B or Diethylenetriaminepentaacetic Acid-Gadolinium (Gd-DTPA) for different times were obtained by 1.5T MRI. The location of B in A549 was detected by Transmission Electron Microscopy. Visualization analysis and half-quantitative analysis were used to determine the signal characteristics. The ANOVA analysis and the paired samples t test were performed by SPSS 13.0.


RESULTS
MALDI TOF-MS molecular weigh of A and B respectively is 3789.74 and 3911.93. Isoelectric point is 11.005T1 Relacion of 0.5 mmol/L Gd-DTPA and B at 17 degrees C respectively is (0.052 +/- 0.01) sec and (0.050 +/- 0.001) sec. Fluorescein uptake assays showed that A translocated into A549 but would be inhibited by MMP2 antibody. Zymography showed both active-MMP2 (67000) and pro-MMP2 (72000) expressed byA549. MR imaging showed A549 incubating with B had a high T(1) signal, and the signal of A549 incubating with Gd-DTPA is similar with that of the control group. Furthermore, ANOVA suggested that the T(1) signal intensity of A549 incubating with B was effected by incubating time (F = 267.569, P < 0.001) and increasing in a time-dependent fashion at the observed time. There is no difference between the T(1) signal intensity of A549 incubating with Gd-DTPA and the control group (P > 0.05). TEM showed A in cytoplasm and nucleus.


CONCLUSIONS
The study in vitro suggests that the MMP-2 activable cell-penetrating peptides bearing contrast media can detect the MMP2-positive tumor cell.
Liu
Min
M
Imaging Center, The 2nd Affiliated Hospital of Medical School, Xi'an Jiao Tong University, Xi'an 710004, China.
Guo
You-min
YM
Wang
Peng
P
Guo
Xiao-juan
XJ
Yang
Jun-le
JL
Wang
Si-cen
SC
Duan
Xiao-yi
XY
Xu
Gui-ping
GP
D014408:Biomarkers, Tumor / Q000737:chemistry / Q000378:metabolism; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D019786:Gadolinium DTPA / Q000737:chemistry; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000737:chemistry / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D014408:Biomarkers, Tumor; D003287:Contrast Media; D010455:Peptides; D020778:Matrix Metalloproteinase 2; D016650:Fluorescein-5-isothiocyanate; D019786:Gadolinium DTPA