BACKGROUND: The present study aimed to validate the accuracy of a tumor-specific antibody to target liver metastases of colorectal cancer. METHODS: A humanized anti-CEA antibody conjugated to a fluorescent dye (M5A-IR800) was tested for targeting human colorectal cancer liver metastases (CRLMs) expressing luciferase in an orthotopic mouse model. Orthotopic mouse models of CRLMs were established by implanting fragments of a luciferase-expressing human colorectal cancer cell line, LS174T, in the liver of nude mice. Mice received 50 µg M5A-IR800 72 h prior to imaging. To test co-localization, bioluminescence imaging was performed using D-luciferin, which was given via intraperitoneal injection just prior to imaging. RESULTS: Tumors were able to be visualized non-invasively through the skin with the luciferase-luciferin signal. Intra-abdominal imaging showed accurate labeling of CRLMs with M5A-IR800, which co-localized with the luciferase-luciferin signal. CONCLUSIONS: The present results validate the accuracy of a tumor-specific anti-CEA antibody in targeting liver metastases of colorectal cancer.

The GGGGCC (G4C2) repeat expansion in a noncoding region of C9orf72 is the most common cause of sporadic and familial forms of amyotrophic lateral sclerosis and frontotemporal dementia. The basis for pathogenesis is unknown. To elucidate the consequences of G4C2 repeat expansion in a tractable genetic system, we generated transgenic fly lines expressing 8, 28 or 58 G4C2-repeat-containing transcripts that do not have a translation start site (AUG) but contain an open-reading frame for green fluorescent protein to detect repeat-associated non-AUG (RAN) translation. We show that these transgenic animals display dosage-dependent, repeat-length-dependent degeneration in neuronal tissues and RAN translation of dipeptide repeat (DPR) proteins, as observed in patients with C9orf72-related disease. This model was used in a large-scale, unbiased genetic screen, ultimately leading to the identification of 18 genetic modifiers that encode components of the nuclear pore complex (NPC), as well as the machinery that coordinates the export of nuclear RNA and the import of nuclear proteins. Consistent with these results, we found morphological abnormalities in the architecture of the nuclear envelope in cells expressing expanded G4C2 repeats in vitro and in vivo. Moreover, we identified a substantial defect in RNA export resulting in retention of RNA in the nuclei of Drosophila cells expressing expanded G4C2 repeats and also in mammalian cells, including aged induced pluripotent stem-cell-derived neurons from patients with C9orf72-related disease. These studies show that a primary consequence of G4C2 repeat expansion is the compromise of nucleocytoplasmic transport through the nuclear pore, revealing a novel mechanism of neurodegeneration.