NAAA is dysregulated in colorectal cancer patients and its inhibition reduces experimental cancer growth.

BACKGROUND AND PURPOSE N-acylethanolamine acid amidase (NAAA) is a lysosomal enzyme accountable for the breakdown of N-acylethanolamides (NAEs) and its pharmacological inhibition determines beneficial effects in inflammatory conditions. The knowledge of NAAA in cancer is fragmentary with an unclarified mechanism whereas its contribution to colorectal cancer (CRC) is unknown to date. EXPERIMENTAL APPROACH CRC xenograft and azoxymethane models assessed the in vivo pharmacological effect of NAAA inhibition; tumor secretome was evaluated by an oncogenic array; CRC cell lines were used for in vitro studies; cell cycle was analyzed by cytofluorimetry; NAAA was knocked down with siRNA; human biopsies were obtained from surgically resected CRC patients; gene expression was revealed by RT-PCR; NAEs were measured by LC-MS. KEY RESULTS The NAAA inhibitor AM9053 reduced CRC xenograft tumor growth and counteracted tumor development in the azoxymethane model. NAAA inhibition impacted the composition of the tumor secretome that negatively affected the expression of epidermal growth factor family members. In CRC cells, AM9053 reduced proliferation with a mechanism mediated by PPAR-α and TRPV1 and induced cell cycle arrest in the S phase with cyclin A2/CDK2 downregulation. NAAA knock-down mirrored the effects of NAAA pharmacological inhibition. NAAA expression was downregulated in human CRC tissues, with a consequential augmentation of NAEs levels and dysregulation of some of their targets. CONCLUSIONS AND IMPLICATIONS Our results provide unprecedented data on the functional importance of NAAA in CRC progression and its mechanism. We propose this enzyme as a valid drug target for the treatment of CRC growth and development.