Figure 3
Figure 3. Tumor accumulation of the CREKA peptide and its N/Cα-methylated variants. Mice bearing orthotropic 22Rv1 xenograft tumors were injected intravenously with 200 μg of FAM-labeled CREKA or N/Cα-methylated CREKA peptides, which were allowed to circulate for 3 hours. This time point highlights the differences between nonmodified CREKA and some of the methylated variants (D). The mice were perfused through the heart with PBS, and the organs shown were collected and viewed under ultraviolet light. (A) Quantification of fluorescence with ImageJ software. Several N/Cα-methylated CREKA analogs produced stronger fluorescence than unmodified CREKA. Statistical analyses were performed with analysis of variance. Error bars show SEM (n = 3-4); **P < .01; ***P < .001. (B-C) Representative images from mice injected with the CREKA or CR(NMe)EKA peptides (B, 22Rv1 xenografts; C, LAPC9 xenografts). In the top panels, white dotted lines show where the organs were placed in a macroscopic examination, and the yellow lines outline the tumor. The bottom panels show confocal images of tumor sections from mice injected with the peptides (green) indicated above. Blood vessels were visualized with anti-CD31 (red); nuclei were stained with DAPI (blue). Bars represent 200 μm. (B right panels) Representative confocal image fields illustrate the localization of the CR(NMe)EKA peptide (green) in relation to anti-fibrin(ogen) (red) and anti-fibronectin (magenta) staining used as markers of tumor stroma; nuclei were stained with DAPI (blue). Bar represents 50 μm. (C right panels) Quantification of fluorescence with ImageJ software. Statistical analysis was performed with Student t test. Error bars show SEM (n = 3); **P < .01. (D) Quantification of fluorescence with ImageJ software 15 minutes or 3 hours after peptide injection into 22Rv1 tumor–bearing mice. CR(NMe)EKA produced stronger fluorescence over time than unmodified CREKA. Statistical analysis was performed with Student t test. Error bars show SEM (n = 3-4); ***P < .001. (NMe) and (CMe) indicate an N- or Cα-methylated residue, respectively.

Tumor accumulation of the CREKA peptide and its N/Cα-methylated variants. Mice bearing orthotropic 22Rv1 xenograft tumors were injected intravenously with 200 μg of FAM-labeled CREKA or N/Cα-methylated CREKA peptides, which were allowed to circulate for 3 hours. This time point highlights the differences between nonmodified CREKA and some of the methylated variants (D). The mice were perfused through the heart with PBS, and the organs shown were collected and viewed under ultraviolet light. (A) Quantification of fluorescence with ImageJ software. Several N/Cα-methylated CREKA analogs produced stronger fluorescence than unmodified CREKA. Statistical analyses were performed with analysis of variance. Error bars show SEM (n = 3-4); **P < .01; ***P < .001. (B-C) Representative images from mice injected with the CREKA or CR(NMe)EKA peptides (B, 22Rv1 xenografts; C, LAPC9 xenografts). In the top panels, white dotted lines show where the organs were placed in a macroscopic examination, and the yellow lines outline the tumor. The bottom panels show confocal images of tumor sections from mice injected with the peptides (green) indicated above. Blood vessels were visualized with anti-CD31 (red); nuclei were stained with DAPI (blue). Bars represent 200 μm. (B right panels) Representative confocal image fields illustrate the localization of the CR(NMe)EKA peptide (green) in relation to anti-fibrin(ogen) (red) and anti-fibronectin (magenta) staining used as markers of tumor stroma; nuclei were stained with DAPI (blue). Bar represents 50 μm. (C right panels) Quantification of fluorescence with ImageJ software. Statistical analysis was performed with Student t test. Error bars show SEM (n = 3); **P < .01. (D) Quantification of fluorescence with ImageJ software 15 minutes or 3 hours after peptide injection into 22Rv1 tumor–bearing mice. CR(NMe)EKA produced stronger fluorescence over time than unmodified CREKA. Statistical analysis was performed with Student t test. Error bars show SEM (n = 3-4); ***P < .001. (NMe) and (CMe) indicate an N- or Cα-methylated residue, respectively.

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