p53-associated metabolic checkpoint regulation in a tick embryo-derived cell line.

The tumor suppressor protein p53 is extensively characterized as a regulator of genome integrity, apoptosis, and metabolic homeostasis in mammalian systems. In early-diverging metazoans, however, p53 metabolic functions remain poorly understood. Here, we investigated the metabolic responses of BME26 cells, an embryonic cell line derived from the cattle tick Rhipicephalus microplus, exposed to PRIMA-1. Pharmacological treatment using PRIMA-1 reduced BME26 cell viability in a dose- and time-dependent manner, exhibiting similar effects to those observed in human breast cancer cells, which were utilized as comparative reference models displaying distinct PRIMA-1 response profiles. Annexin V/7-AAD staining and morphological analyses showed that the decrease in BME26 viability was primarily caused by apoptosis. Metabolomic profiling by 1H-13C HSQC NMR revealed coordinated changes in central carbon metabolism, amino acid pathways, and choline-derived metabolites, indicating broad metabolic remodeling upon PRIMA-1 exposure. Despite showing no effect on glucose uptake and glycogen content, PRIMA-1 selectively reduced the expression of key glycolytic genes, including hexokinase (HK) and pyruvate kinase (PK), and significantly reduced glucose-6-phosphate dehydrogenase (G6PDH) gene expression. This was accompanied by decreased intracellular NADPH levels, while isocitrate dehydrogenase-1 (IDH-1) gene expression remained unaffected, suggesting a pathway-specific metabolic modulation rather than global energetic collapse. Collectively, our findings demonstrate that PRIMA-1 treatment in tick embryonic cells restricts glycolytic and pentose phosphate pathway flux, limiting NADPH production and reshaping redox balance to favor apoptosis. These results support the potential conservation of metabolic pathways sensitive to PRIMA-1, which in mammalian systems are linked to modulation of the p53-G6PDH-NADPH axis, thereby expanding our understanding of metabolic regulation and stress responses in arthropod biology.