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The Role of Indoleamine 2,3‐Dioxygenase (IDO) on PC‐3 Prostate Cancer Cells Viability
Author(s) -
Matos Yves Silva Teles,
Oliveira Brito Rodrigo Barbosa,
Matheus Luiz Henrique Gomes,
Souza Diego Mota,
Malta Camila Souza,
GiannellaNeto Daniel,
PontesJunior José,
Dellê Humberto
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.698.18
Subject(s) - indoleamine 2,3 dioxygenase , immune system , cancer cell , kynurenine , cancer , prostate cancer , cancer research , viability assay , chemistry , immunology , biology , medicine , tryptophan , cell , biochemistry , amino acid
According to the American Cancer Society, the prostate cancer (PCa) has the highest incidence and the second‐leading cause of death in men, behind only lung cancer. Among the mechanisms used to escape from the immune system, cancer cells can utilize immunomodulatory molecules such as indoleamine 2,3‐dioxygenase (IDO). IDO catalyzes the degradation of tryptophan which lead to accumulation of tryptophan metabolites, such as kynurenine, that contribute to its immune‐suppressive response towards T cells and thus promoting immune escape for the cancer cells. Although IDO has been pointed as a protective molecule in several types of cancer, promoting tolerance to tumors, IDO has shown paradox effect in renal and ovary cancers, demonstrating anti‐tumor effects. Although studies have shown the anti‐tumor effect of IDO as well, there are no studies showing the relation between IDO and PCa cells. The aim of the present study was to evaluate the effect of IDO inhibition on human prostate cancer PC3 cells viability. PC3 cells were incubated with or without interferon‐gamma (INF; a strong inductor of IDO) and total RNA was extracted to analyze the expression of IDO by RT‐qPCR. Furthermore, to evaluate the effect of IDO on PC3 cells viability we carried out MTT assay. PC3 cells were seed in 96‐well plaque (1×10 4 cells per well) and then after 48h were incubated with serum‐free RPMI medium for 24h in the following conditions: CONTROL, only medium; MT, medium containing 0.5mM 1‐methyl‐D‐tryptophan (MT, an inhibitor of IDO); KYN, medium containing 0.5mM kynurenine. The results are presented as mean ± SEM and One‐Way ANOVA was used for statistical analysis with comparisons according to Newman‐Keuls. PC3 cells express IDO constitutively in culture and when stimulated with INF this expression was increased (CT of 30.07 in Control vs. 22.39 in INF‐treated cells; CT of 24.48 in Control vs. 23.74 in INF‐treated cells for TBP housekeeping gene). The MTT assay has shown that stimulus with MT increases cell viability (optical density of 0.21±0.01 vs. 0.19±0.03 in control; p<0.05). However, when treated with kynurenine, there was a significant decrease in viability (KYN=0.15±0.02 vs Control=0.19±0.03; P<0.05). These preliminary results show that PC3 cells produce constitutively IDO and its expression increase when the cells are exposed to interferon‐gamma. When IDO is inhibited by MT, the viability is increased, and the viability is decreased in the presence of Kyn, pointing that IDO has an antitumoral effect on PCa.