To explore the changes in serum energy metabolites in patients with peripheral T-cell lymphoma, and investigate serum biomarkers for monitoring peripheral T-cell lymphoma from the perspective of energy metabolism.

Multiple/selected reaction monitoring (MRM/SRM) was used to detect the energy-related metabolites in the sera of 16 patients with newly diagnosed peripheral T-cell lymphoma admitted in the Hematology Medical Center of the Second Affiliated Hospital of Army Medical University from November 2020 to December 2021, as well as 10 recruited healthy volunteers.The corresponding clinical data including medical history, laboratory results and image data were collected and retrospectively analyzed.

Significant differences were seen in the contents and expression profiles of serum energy metabolism-related products between the patients and the healthy volunteers. The patients had significantly reduced serum contents of cyclic AMP, succinate, citrate and cis-aconitate (P < 0.05), and elevated D-glucose 6-phosphate content (P < 0.05).The serum contents of citrate and succinate were negatively correlated with the risk stratification (low-, moderate-and high-risk) and clinical stage of the disease (P < 0.05).Meanwhile, there was a negative correlation between the contents of L-malic acid and citrate and the mid-term efficacy evaluation results, such as complete/partial response (CR/PR) or stable disease (SD)(P < 0.05).For patients with extranodal NK/T cell lymphoma (n=10), there were also significant reductions in the contents of cyclic AMP, succinate, citrate, isocitrate and cis-aconitate in the sera of patients compared with healthy volunteers (P < 0.05), and the contents of citrate and succinate were negatively correlated with the clinical stage (P < 0.05) and were rather correlated with mid-term efficacy evaluation results (CR/PR or SD)(P < 0.05).For patients with angioimmunoblastic T-cell lymphoma (n=6), the serum contents of cyclic AMP, citrate and succinate were significantly lower, while the content of D-glucose 6-phosphate was higher when compared with the healthy volunteers (P < 0.05), and the content of succinate was negatively correlated with both clinical stage and risk grade of the patients (P < 0.05).

There are 5 serum differential metabolites identified between patients with peripheral T-cell lymphoma and healthy controls, and succinate and citrate are expected to be serum biomarkers of peripheral T-cell lymphoma.

To preliminarily investigate the anti-tumor effects of phytosphingosine (PHS) and the involvement of inducing apoptosis of leukemia cells.

Cellular model of leukemia was established in leukemia cell lines K562 and SUP-B15.CCK-8 assay and EdU assay were used to measure the viability and DNA synthesis of K562 and SUP-B15 cells. RNA-seq was carried out to verify the differentially expressed genes (DEGs) after PHS treatment.Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were applied to analyze the involved functions and signaling pathways. Comparative Toxicogenomics Database (CTD) and Discovery Studio software were employed to predict the underlying targets of PHS and molecular docking.Cell apoptosis was detected by flow cytometry, mitochondrial membrane potential was evaluated by JC-1 probe, and protein expression of key molecules was validated by Western blotting.

PHS inhibited the proliferation of K562 and SUP-B15 cells in a time-and dose-dependent manner.The half-maximal inhibitory concentration (IC₅₀) of K562 cells was 17.67 and 12.52 μmol/L for 24 and 48 h, respectively, and the IC₅₀ value of SUP-B15 cells was 17.58 and 14.86 μmol/L for 24 and 48 h, respectively.PHS treatment at a dose of 20 μmol/L for 48 h resulted in significant inhibition of DNA synthesis.GO enrichment analysis of the K562 cells showed that PHS might be involved in positive regulation of apoptotic process, plasma membrane and its integral components, and protein kinase binding and activity.Reverse predictive analysis showed that BCL-2 protein was the most likely target of PHS.PHS significantly increased the apoptotic rate of leukemia cells (P < 0.05) in a dose-dependent manner, reduced the mitochondrial membrane potential, and down-regulated BCL-2 level (P < 0.05) and up-regulated the levels of Cleaved caspase-3 and Cleaved caspase-9(P < 0.05).

PHS may inhibit the proliferation of leukemia cells by inducing mitochondria-dependent apoptosis, possibly through PHS and BCL-2 interaction.