Expression profiles of lncRNAs H19, SPRY4-IT1, and XIST and their association with IDO1 and TDO2 in breast cancer

Breast cancer (BC) progression is driven by complex interactions involving epigenetic dysregulation, metabolic reprogramming, and immune escape. Long non-coding RNAs (lncRNAs) and activation of the kynurenine pathway have been implicated in these processes; however, their potential interplay remains poorly understood. This study evaluated the expression profiles of lncRNAs H19, SPRY4-IT1, and XIST and their association with serum indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase 2 (TDO2) concentrations in BC patients. The study included 50 newly diagnosed BC patients and 30 healthy controls. Expression levels of H19, SPRY4-IT1, and XIST were quantified by reverse transcription quantitative polymerase chain reaction (RT-qPCR), while serum IDO1 and TDO2 concentrations were measured using enzyme-linked immunosorbent assay (ELISA). SPRY4-IT1 and H19 expression levels were significantly increased in BC patients, whereas XIST expression was significantly decreased. Serum IDO1 and TDO2 concentrations were significantly elevated in the patient group. Correlation analysis revealed a positive association between SPRY4-IT1 expression and IDO1 concentration, while XIST expression was inversely associated with TDO2 concentration. A significant positive correlation was also observed between IDO1 and TDO2 levels. Most molecular markers showed no significant association with clinicopathological characteristics except for IDO1, which was associated with progesterone receptor status. These findings suggest that dysregulated lncRNA expression and activation of the IDO1/TDO2–kynurenine pathway may contribute to immune-metabolic alterations in BC and warrant further investigation as potential biomarkers for breast cancer progression.