Serum Tryptophan and Kynurenine Concentrations as Parameters for Indoleamine 2, 3-Dioxygenase Activity in Patients With Endometrial, Ovarian, and Vulvar Cancer. Issue 7 (1st October 2011)

• Record Type: Journal Article
• Authors: de Jong, Renske A.; Nijman, Hans W.; Boezen, H. Marike; Volmer, Marcel; ten Hoor, Klaske A.; Krijnen, Jasper; van der Zee, Ate G.J.; Hollema, Harry; Kema, Ido P.
• Is Part Of: International journal of gynecological cancer. Volume 21:Issue 7(2011)
• Page Start: 1320
• Page End: 1327
• Publication Date: 2011-10-01
• Subjects: Indoleamine 2, 3-dioxygenase -- Tryptophan -- Endometrial cancer -- Ovarian cancer -- Vulvar cancer; Generative organs, Female -- Cancer -- Periodicals; 616.99465
• DOI: 10.1097/IGC.0b013e31822017fb
• Languages: English
• ISSNs: 1048-891X

Abstract

Abstract : Objective: Indoleamine 2, 3-dioxygenase (IDO) suppresses the function of T-lymphocytes and is involved in immune escape of cancers. Indoleamine 2, 3-dioxygenase catalyzes the initial rate-limiting step in the degradation of the essential amino acid tryptophan. In this study, we investigated cancer-induced IDO activity in sera of endometrial, ovarian, and vulvar cancer patients. Methods: Concentrations of tryptophan and kynurenine were determined in pretreatment serum samples of patients with endometrial (n = 41), ovarian (n = 28), and vulvar cancer (n = 40) and compared to 19 healthy female controls. In serum of a subgroup of endometrial (n = 22), ovarian (n = 21), and vulvar (n = 21) cancer patients, tryptophan, kynurenine, and the kynurenine-to-tryptophan ratio (kyn/trp) were determined at different time points: preoperative, at clinical remission, and at the time of diagnosis of recurrent disease. Analyses were performed by an automated online solid-phase extraction-liquid chromatographic-tandem mass spectrometric method. Indoleamine 2, 3-dioxygenase activity was estimated by calculating the kyn/trp ratio. Results: Kynurenine concentrations and the kyn/trp ratio were higher in preoperative serum of endometrial, ovarian, and vulvar cancer patients compared to controls (all: P < 0.001). Preoperative serum of ovarian cancer patients contained higher kynurenine concentrations (median, 2.53 μM; interquartile range [IQR], 1.72-4.29 μM) and a higher kyn/trp ratio (median, 39.3 μmol/mmol; IQR, 26.5-61.7 μmol/mmol) compared to serum collected at clinical remission (median, 2.02 μM; IQR, 1.68-2.72 μM, P = 0.035; and median, 29.9 μmol/mmol; IQR, 23.4-38.9 μmol/mmol, P = 0.005, respectively). Conclusions: Patients with endometrial, ovarian, and vulvar cancer have increased tryptophan degradation compared to controls resulting in higher serum kynurenine concentrations and a higher kyn/trp ratio. Our results suggest that IDO-induced immune escape may play an important role in these gynecologic cancers.