Antitumor activity of iNGR-GRIM-19 in colorectal cancer.

BACKGROUND

Gene associated with retinoid-interferon induced mortality-19 (GRIM-19) plays crucial roles in carcinogenesis.

OBJECTIVE

To explore the antitumor activity of internalizing NGR (iNGR) gene associated with GRIM-19 in colorectal cancer.

METHODS

Cells were incubated with fluorescein isothiocyanate-labeled fusion proteins followed by fluorescence microscopic analysis. Cell proliferation was determined by MTT assay. Cell cycle was analyzed by flow cytometric analysis. Cell migration and invasion capacity were evaluated by wound scratch and Transwell assays, respectively. Apoptosis was measured by Annexin V/PI staining and TUNEL assay. Gene expressions were determined by RT-PCR and Western blotting. Nude mice bearing colorectal cancer received vehicle, GRIM-19, or iNGR-GRIM-19 fusion protein injection, and the in vivo antitumor capacity of the fusion proteins was examined.

RESULTS

iNGR-GRIM-19 was specifically taken up by human colorectal cancer Colo205 cells, but not corneal epithelial (HCEpic) cells, whereas GRIM-19 was not internalized by either cell type. Unlike GRIM-19, incubation with iNGR-GRIM-19 dose-dependently inhibited proliferation, induced G1 phase arrest, suppressed cell migration and invasion, and caused apoptosis in Colo205 cells. Additionally, injection of iNGR-GRIM-19 extended the lifespan of colorectal cancer-bearing nude mice and reduced in vivo tumor growth as compared with vehicle or GRIM-19 treatment. iNGR-GRIM-19 was localized only in the tumor mass, without affecting other tissues, such as liver or kidney. iNGR-GRIM-19 injection led to G1 phase arrest and induced cell apoptosis in xenografted colorectal cancer tissues.

CONCLUSIONS

iNGR-GRIM-19 has an efficient antitumor activity in vitro and in vivo, and might be a promising agent for the treatment of colorectal cancer.