Picolinic acid, a tryptophan metabolite, triggers cellular senescence by targeting NOS/p38 MAPK/CK1α/MLKL signaling and metabolic exhaustion in red blood cells

Anemia is among the most commonly reported adverse events of anticancer therapy. Picolinic acid (PA), an endogenous metabolite of tryptophan degradation in the kynurenine pathway, is a metal chelator with an anticancer activity. The objective of the current study is to investigate the modulation of red blood cell (RBC) lifespan by PA. Hemolytic and eryptotic markers were evaluated in the presence and absence of PA by photometric and flow cytometric methods. PA demonstrated a dual effect on hemolysis in which it was pro-hemolytic in isotonic media but anti-hemolytic under hypotonic challenge. PA also induced RBC senescence with reduced AChE activity. In addition, treated cells tested positive for annexin-V and Fluo4 and had a significantly lower forward scatter signal. Notably, ATP-replenished cells showed significantly enhanced chemoresistance against PA toxicity, which was also alleviated by ascorbic acid, L-NAME, SB203580, D4476, and necrosulfonamide. Furthermore, an inhibitory effect on PA was observed in incubation media supplemented with isosmotic sucrose but not urea. These data suggest that PA accelerates RBC aging through anticholinesterase activity and exhibits hemolytic and eryptotic properties characterized by phosphatidylserine externalization, Ca2+ mobilization, cell shrinkage, metabolic shutdown, and stimulation of the NOS/p38 MAPK/CK1 alpha/MLKL pathway.