Indoleamine 2,3-Dioxygenase (IDO) catalyses the degradation of the essential amino acid tryptophan leading to the production of immunosuppressive Kynurenine. In the present study, we developed a modified method for measurement of Kynurenine/tryptophan (K/T) ratio in the cervical tissue using HPLC and investigated its relationship with the expression of IDO1 and 2 genes in the cervical tumour milieu.
Cervical cancer punch biopsy samples of 27 women who presented at the Cancer Institute (WIA) were used for detection of K/T ratio by HPLC as well as expression of IDO1 and 2 at the mRNA level by Realtime PCR after obtaining Institutional ethical committee approval.
The K/T ratio was elevated significantly in cancer cervix samples compared to normal cervix (p<0.05). IDO1 mRNA levels were up-regulated whereas IDO2 mRNA levels were down-regulated in cancer cervix compared to the normal cervix. A positive correlation was observed between IDO1 and K/T (p<0.05) indicating that IDO1 was responsible for the increase in K/T ratio.
Our preliminary data indicates that the K/T ratio at the tissue level may be investigated reliably using HPLC, as an indirect measure of IDO1 gene expression and activity.
Clinical biochemistry. 2016 Apr 20 [Epub]
Jayakumar Hascitha, Ramanathan Priya, Subramani Jayavelu, Hemavathi Dhandapani, Ganeshrajah Selvaluxmy, Shirley Sunder Singh, Thangarajan Rajkumar