Fig 1.
The structure of HER2 aptamer.
The predicted secondary structure of aptamer SH-1194-35 based on a lowest free energy model (A) and schematic mechanism (B) of radioisotope- or fluorescence-labeled aptamer.
Fig 2.
HER2 expression characteristics as determined by western blotting of human breast cancer cell lines.
The BT474 and SK-BR3 cell lines highly expressed HER2, whereas MDA-MB231 and HS578T cells had no detectable HER2 expression. Beta-actin was used as a loading control.
Fig 3.
Flow cytometry analysis of breast cancer cell lines using HER2 antibody and aptamer.
(A) Dot plots representing the fluorescence signals for BT474 (HER2-positive cells), MDA-MB231 (HER2-negative cells) from monoclonal antibody, and SH-1194-35 aptamer (red) or scrambled random sequence (blue). (B) Flow cytometric histogram of two cells using antibody, aptamer, and negative control.
Fig 4.
Confocal microscopic images of selected aptamer binding to HER2-positive cells.
(A) BT474, HER2-positive breast cancer cells were incubated with FITC-labeled aptamer. (B) MDA-MB231 cancer cells were treated with the same aptamer. (Labeling, blue: DAPI; green: FITC-aptamer).
Fig 5.
Biodistribution of 18F-labeled HER2 aptamer.
Biodistribution study of 18F-labeled HER2 aptamer in BT474 tumor-bearing mice. Data are expressed as a percentage of injected activity per gram of tissue (%ID/g). Error bars, SD (N = 4).
Fig 6.
Representative images of in vivo 18F-labeled HER2-aptamer PET in HER2-positive and negative tumor-bearing mice.
(A) HER2 overexpressing BT474 tumor shows increased uptake, compared to the (B) HER2-negative MB-MDA231 tumor. (C) %ID/g of tumor calculated from 18F-labeled HER2 aptamer. The %ID/g of aptamer in the BT474 tumor were significantly higher than those in the MDA-MD231 tumor.
Fig 7.
Representative staining results from H&E and IHC for HER2 (original magnification 400X).
Immunohistochemically, the BT474 tumor cells (upper row) show strong membranous staining for HER2, compared to MDA-MB231 cells (lower row).