Inhibition of Colon Carcinogenesis by 2-Methoxy-5-Amino-N-Hydroxybenzamide, a Novel Derivative of Mesalamine

Abstract

Mesalamine has been reported to protect against inflammatory bowel disease-related colorectal cancer (CRC), but several drug-related issues have limited its use in chemopreventive programs. We evaluated the antineoplastic properties of mesalamine derivatives using in vitro and in vivo models of CRC. CRC cell proliferation and cell-cycle progression were evaluated by flow cytometry after exposure to mesalamine or mesalamine derivatives. Cyclins, cyclin-dependent kinases, and endoplasmic reticulum stress-related molecules were examined by immunoblotting. The in vivo antineoplastic effect of 2-methoxy-5-amino-N-hydroxybenzamide (2-14) was evaluated in a syngenic, CT26-derived xenograft mouse model of CRC and in the azoxymethane/dextran sulfate sodium-induced mouse model of colitis-associated CRC. The mesalamine derivative 2-14 was 10-fold more potent than mesalamine in inhibiting CRC cell proliferation. After exposure to 2-14, cyclin D1 expression was reduced and G0/G1 phase cells accumulated. These events were preceded by activation of eukaryotic translation initiation factor 2-alpha kinase 3 (pancreatic endoplasmic reticulum eIF2alpha kinase), phosphorylation of eukaryotic translation initiation factor 2alpha, induction of activating transcription factor 4, and splicing of X-box binding protein 1 messenger RNA, events that define endoplasmic reticulum stress. Silencing of PERK restored cyclin D1 levels, allowing cells to overcome the cell-cycle block induced by 2-14. Mice injected with 2-14 developed fewer CRC xenograft-derived tumors. Moreover, 2-14 injection reduced the development of neoplastic lesions induced by azoxymethane and dextran sulfate sodium in mice. The mesalamine derivative 2-14 inhibited CRC cell proliferation in vitro and prevented CRC progression in mouse models.