NEUROTENSIN PROMOTES FUNCTION OF COLORECTAL CANCER STEM CELLS

Colorectal cancer (CRC) is the third major cause of cancer-related death in the world. CRC usually originates from genetic modifications of a small niche of self-renewing colonic stem cells that play a major role in tissue repair after injury. Neurotensin (NT), an obesogenic hormone, stimulates CRC cell proliferation and is significantly increased in plasma of CRC patients. Our previous study revealed that NT regulates stem cell function in the small intestine through activation of Wnt/β-catenin signaling. The purpose of our current study was to determine if NT promotes stem cell function in CRC. METHODS. Expression of NT, neurotensin receptor 1 (NTR1) and stemness markers (Lgr5, Olfm4, CD44) were analyzed in paired normal colon and CRC tissue samples from patients undergoing surgery using PCR and western blot analyses. Stem cell function was assessed by organoid formation assay, limiting dilution assay (LDA), and drug (5-Fluorouracil) resistance capacity in CRC cell lines and patient-derived organoids treated with NT (10-100nM). NT-induced cell signaling pathways were analyzed using western blot and PCR analyses. RESULTS. We show that NTR1 expression is significantly increased and positively correlates with increased stem cell markers in CRC patient samples. Exogenous NT treatment increased the organoid formation efficiency of CRC cell lines and patient-derived samples; which was further confirmed by LDA analyses. NT also promoted organoid survival in the presence of 5-Fluorouracil-induced chemotherapeutic cell death. Mechanistically, NT activates MAPK/Wnt/β-catenin signaling in CRC cells which results in increased expression of stem cell markers Lgr5, Olfm4 and CD44. CONCLUSION. Our study identifies a novel role for NT in promoting CRC progression and survival by activating stemness markers, which suggests that NT/NTR1 signaling can be therapeutically targeted for CRC.