The expression and prognostic relevance of indoleamine 2,3-dioxygenase in tongue squamous cell carcinoma

Abstract

Conclusion IDO might be useful for predicting progression of primary tumor stage T2 and T3 in tongue squamous cell carcinoma (TSCC), but does not seem like a specific biomarker for diagnosing TSCC and predicting patient survival. Objectives Indoleamine 2,3-dioxygenase (IDO) is expressed in many cells and it catabolises the essential amino acid tryptophan to kynurenine. IDO acts as an immune modulator through suppression of T-cell immunity and other pathways. In cancer cells, IDO has been proposed to promote tumor progression by enabling malignant cells to escape from the immune system. The aim of this study was to evaluate the association and prognostic relevance of IDO expression in TSCC. Method One hundred and eight retrospective tongue and lymph node specimens were stained immunohistochemically with monoclonal antibody anti-indoleamine 2,3-dioxygenase. The relative abundance of IDO positive epithelial cells, IDO staining intensity, and inflammation were assessed semi-quantitatively with light microscopy. Results IDO was expressed stronger in tongue hyperplasia than in TSCC. However, IDO expression associated with poor survival in the sub-groups with primary tumor stage T2–T4 and in the sub-group with strong inflammation in tumors’ invasive front.

Keywords:

• Indoleamine 2,3-dioxygenase
• inflammation
• tongue squamous cell carcinoma
• survival
• immunohistochmistry

Acknowledgements

The study was supported by the Competitive Research Funding of the Tampere Medical Research Fund of Tampere University Hospital, and in part by research grants from the Finnish Medical Foundation, Finnish Association of Otorhinolaryngology and Head & Neck Surgery, Jane & Aatos Erkko Foundation, Paulo Foundation, Väinö and Laina Kivi Foundation, and Yrjö Jahnsson Foundation. We thank Eini Eskola and Teemu Honkanen for excellent technical assistance.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.