Fig. 1: Spermine and Serpinb9 are associated with pancreatic tumor progression and poor prognosis.

a Quantification of polyamines in plasma from healthy individuals (n = 10), PR (n = 20) patients, and PD patients (n = 8) with PDAC. b OS of PDAC patients with high or low plasma spermine concentrations (n = 40 patients). c Correlation between spermine levels in TIF and intratumoral CD8⁺ T cells (n = 40 patients). d Intersection of differentially expressed genes from four pancreatic cancer datasets with T cell dysfunction-related genes. e Extracellular relative spermine levels in BxPC-3 cells after the top seven genes knockdown (n = 3 biologically independent samples). f Positive correlation between Serpinb9 expression and spermine levels in PDAC patients (n = 40 patients). g Representative staining and negative correlation between Serpinb9 expression and CD8⁺ T cell infiltration in PDAC tissues (n = 40 patients). Scale bars: 50 μm. H-score: histological score. h Uniform manifold approximation and projection (UMAP) of scRNA-seq from PDAC tumors showing 10 clusters. i Dot plot of canonical marker expression in each cluster. j Representative UMAP plot displaying the distribution of Serpinb9 expression in tumor versus normal tissues. k Quantification of Serpinb9 in different cell types, including ductal, T, myeloid, and CAFs. l Representative staining of Serpinb9, pan-CK, CD3, CD68, and ASMA in tumor and paired normal tissues. m Quantification of Serpinb9 in different cell types (n = 7 patients). n, o Association between Serpinb9 expression and tumor grade or TNM stage (n = 148 patients). p OS of all patients with pancreatic cancer, stratified by high versus low Serpinb9 expression (n = 112 patients). q, r OS (q), and disease-specific survival (DSS) (r) of pancreatic cancer patients in TCGA, based on Serpinb9 expression. For a, e, k, m, n, and o, data were presented as mean ± S.D. For b and p–r data were generated using Kaplan-Meier survival curves based on log-rank tests. For c, f, and g Spearman correlations and P values were calculated using a two-sided Spearman’s test. Statistical significance was determined using two-sided unpaired Student’s t-test or one-way ANOVA followed by Tukey’s post hoc test. Box plots show the median (center line), 25th–75th percentiles (box), and whiskers (1.5×IQR range). Source data are provided as a Source Data file.