Abstract 1447: Aberrant tryptophan catabolism marked by high kynureninase expression contributes to immunosuppression and poor outcome in lung adenocarcinoma

• Published in: Cancer research (Chicago, Ill.) Ill.), 2018-07, Vol.78 (13_Supplement), p.1447-1447
• Main Authors: Ostrin, Edwin J., Fahrmann, Johannes F., Tanaka, Ichidai, Celiktas, Muge, Aguilar, Clemente, Aguilar, Mitzi, Dennison, Jennifer B., Murage, Eunice, Tripathi, Satyendra C., Delgado, Oliver, Wang, Hong, Rodriguez-Canales, Jaime, Behrens, Carmen, Wistuba, Ignacio I., Taguchi, Ayumu, Hanash, Samir M.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2018-1447

Low tryptophan levels promote tumor immune evasion by suppressing immune function. Elucidation of the immunomodulatory effects of altered tryptophan catabolism has relevance to cancer immunotherapy. Previous studies have largely focused on the role of the rate-limiting enzyme indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan depletion in the microenvironment. However, IDO1 levels are highly heterogeneous in different cancers, and numerous other downstream tryptophan catabolites have also been shown to have immunomodulatory activity. We surveyed the proteomes of 123 cancer cell lines for regulators of tryptophan metabolism which revealed overexpression of kynureninase (KYNU) in KEAP1 mutant lung adenocarcinomas. Functional analysis indicated that KYNU expression is regulated through nuclear factor, erythroid 2-like (Nrf2) activation. KYNU-high cell lines exhibited increased secretion of KYNU-derived anthranilate/3-hydroxyanthranilate. Ex-vivo studies using isolated PBMCs demonstrated that 3-hydroxyanthranilate reduced CD8+ T-cell viability. KYNU mRNA expression in three independent datasets of lung adenocarcinomas and additionally KYNU protein expression in lung adenocarcinoma tissue microarrays revealed that high KYNU expression predicts poor survival and disease recurrence. Our findings indicate that KYNU promotes immune suppression and is an independent prognostic marker for lung adenocarcinoma. Citation Format: Edwin J. Ostrin, Johannes F. Fahrmann, Ichidai Tanaka, Muge Celiktas, Clemente Aguilar, Mitzi Aguilar, Jennifer B. Dennison, Eunice Murage, Satyendra C. Tripathi, Oliver Delgado, Hong Wang, Jaime Rodriguez-Canales, Carmen Behrens, Ignacio I. Wistuba, Ayumu Taguchi, Samir M. Hanash. Aberrant tryptophan catabolism marked by high kynureninase expression contributes to immunosuppression and poor outcome in lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1447.